v13 release notes (2)

It seems that chocolately doesn't put gswin[32,64]c on PATH anymore,
so compensate.

.docker/Dockerfile

@@ -0,0 +1,80 @@
+# OCRmyPDF
+#
+
+FROM ubuntu:21.04 as base
+
+ENV LANG=C.UTF-8
+ENV TZ=UTC
+RUN echo 'debconf debconf/frontend select Noninteractive' | debconf-set-selections
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+  python3 \
+  libqpdf-dev \
+  zlib1g \
+  liblept5
+
+FROM base as builder
+
+# Note we need leptonica here to build jbig2
+RUN apt-get update && apt-get install -y --no-install-recommends \
+  build-essential autoconf automake libtool \
+  libleptonica-dev \
+  zlib1g-dev \
+  python3-dev \
+  python3-distutils \
+  libffi-dev \
+  ca-certificates \
+  curl \
+  git
+
+# Get the latest pip (Ubuntu version doesn't support manylinux2010)
+RUN \
+  curl https://bootstrap.pypa.io/get-pip.py | python3
+
+# Compile and install jbig2
+# Needs libleptonica-dev, zlib1g-dev
+RUN \
+  mkdir jbig2 \
+  && curl -L https://github.com/agl/jbig2enc/archive/ea6a40a.tar.gz | \
+  tar xz -C jbig2 --strip-components=1 \
+  && cd jbig2 \
+  && ./autogen.sh && ./configure && make && make install \
+  && cd .. \
+  && rm -rf jbig2
+
+COPY . /app
+
+WORKDIR /app
+
+RUN pip3 install --no-cache-dir .[test,webservice,watcher]
+
+FROM base
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+  ghostscript \
+  img2pdf \
+  libsm6 libxext6 libxrender-dev \
+  pngquant \
+  tesseract-ocr \
+  tesseract-ocr-chi-sim \
+  tesseract-ocr-deu \
+  tesseract-ocr-eng \
+  tesseract-ocr-fra \
+  tesseract-ocr-por \
+  tesseract-ocr-spa \
+  unpaper \
+  && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+
+COPY --from=builder /usr/local/lib/ /usr/local/lib/
+COPY --from=builder /usr/local/bin/ /usr/local/bin/
+
+COPY --from=builder /app/misc/webservice.py /app/
+COPY --from=builder /app/misc/watcher.py /app/
+
+# Copy minimal project files to get the test suite.
+COPY --from=builder /app/setup.cfg /app/setup.py /app/README.md /app/
+COPY --from=builder /app/tests /app/tests
+
+ENTRYPOINT ["/usr/local/bin/ocrmypdf"]

.dockerignore

@@ -0,0 +1,44 @@
+# dotfiles
+.*
+!.coveragerc
+!.dockerignore
+!.git_archival.txt
+!.gitattributes
+!.gitignore
+!.pre-commit-config.yaml
+!.readthedocs.yml
+
+# Dev scratch
+*.ipynb
+**/*.pyc
+/*.pdf
+/*.qdf
+/*.png
+/scratch.py
+IDEAS
+log/
+tests/resources/private/
+tmp/
+venv*/
+/debug_tests.py
+*.traineddata
+/private
+
+# Package building
+*.egg-info/
+build/
+dist/
+wheelhouse/
+pip-wheel-metadata/
+
+# Code coverage
+htmlcov/
+
+# Docker specific
+bin/
+docs/
+include/
+lib/
+
+# Docker include .git/
+!.git/

.git_archival.txt

@@ -0,0 +1 @@
+ref-names: $Format:%D$

.gitattributes

@@ -5,4 +5,10 @@
 # (binary is a macro for -text -diff)
 *.jar	binary
 *.pdf	binary
-*.PDF	binary
+*.PDF	binary
+*.png	binary
+*.jpg	binary
+*.bin   binary
+*.afdesign  binary
+
+.git_archival.txt  export-subst

.github/FUNDING.yml

@@ -0,0 +1,12 @@
+# These are supported funding model platforms
+
+github: # Replace with up to 4 GitHub Sponsors-enabled usernames e.g., [user1, user2]
+patreon: # Replace with a single Patreon username
+open_collective: james-barlow
+ko_fi: # Replace with a single Ko-fi username
+tidelift: # Replace with a single Tidelift platform-name/package-name e.g., npm/babel
+community_bridge: # Replace with a single Community Bridge project-name e.g., cloud-foundry
+liberapay: # Replace with a single Liberapay username
+issuehunt: # Replace with a single IssueHunt username
+otechie: # Replace with a single Otechie username
+custom: # Replace with up to 4 custom sponsorship URLs e.g., ['link1', 'link2']

.github/ISSUE_TEMPLATE/1-general-issues.md

@@ -0,0 +1,32 @@
+---
+name: General issues
+about: Installation, packages, dependencies, "nothing works", test suite failures...
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Describe the bug**
+What's the problem?
+
+**To Reproduce**
+Steps to reproduce the behavior.
+
+**Expected behavior**
+What did you expected to happen?
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**System (please complete the following information):**
+ - OS:
+ - Python version:
+ - OCRmyPDF version:
+
+**Installation**
+How did you install OCRmyPDF? Did you install it from your operating system's
+package manager, or using pip?
+
+**Additional context**
+Add any other context about the problem here.

.github/ISSUE_TEMPLATE/2-problem-with-a-specific-input-file.md

@@ -0,0 +1,40 @@
+---
+name: Problem with a specific input file
+about: Something went wrong while trying to OCR a specific file
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+What command line or API call were you trying to run?
+
+```bash
+ocrmypdf  ...arguments... input.pdf output.pdf
+```
+
+Run with verbosity or higher `-v1` to see more detailed logging. This information may be helpful.
+
+**Example file**
+If your issue is a problem that affects only certain files, and we will require an input file (PDF or image) that demonstrates your issue.
+
+Please provide an input file with no personal or confidential information. At your option you may [GPG-encrypt the file](https://github.com/jbarlow83/OCRmyPDF/wiki) for OCRmyPDF's author only.
+
+Links to files hosted elsewhere are perfectly acceptable. You could also look in ``tests/resources`` and see if any of those files reproduce your issue.
+
+*(Issues without example files usually cannot be resolved. It's like reporting an issue against a web browser without providing a URL.)*
+
+**Expected behavior**
+A clear and concise description of what you expected to happen.
+
+**Screenshots**
+If applicable, add screenshots to help explain your problem.
+
+**System**
+ - OS: [e.g. Linux, Windows, macOS]
+ - OCRmyPDF Version: ``ocrmypdf --version``
+ - How did you install ocrmypdf? Did you use a system package manager, `pip`, or a Docker image?

.github/ISSUE_TEMPLATE/3-feature_request.md

@@ -0,0 +1,27 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Is your feature request related to a problem? Please describe.**
+A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+
+**Describe the solution you'd like**
+A clear and concise description of what you want to happen.
+
+**Describe alternatives you've considered**
+A clear and concise description of any alternative solutions or features you've considered. Please include the versions of OCRmyPDF and other supporting programs (Tesseract OCR, Ghostscript) - maybe an alternative already exists in a newer version.
+
+**Example file**
+If your issue concerns how OCRmyPDF processes certain files, and please provide an example file that helps illustrate how OCRmyPDF's output could be improve.
+
+Please provide an input file with no personal or confidential information. At your option you may [GPG-encrypt the file](https://github.com/jbarlow83/OCRmyPDF/wiki) for OCRmyPDF's author only.
+
+Links to files hosted elsewhere are perfectly acceptable. You could also look in ``tests/resources`` and see if any of those files reproduce your issue.
+
+**Additional context**
+Add any other context or screenshots about the feature request here.

.github/workflows/build.yml

@@ -0,0 +1,302 @@
+name: Test and deploy
+
+on:
+  push:
+    branches:
+      - master
+      - ci
+      - release/*
+      - feature/*
+    tags:
+      - v*
+    paths-ignore:
+      - README*
+  pull_request:
+
+jobs:
+  test_linux:
+    name: Test ${{ matrix.os }} with Python ${{ matrix.python }}
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        include:
+          - os: ubuntu-18.04
+            python: 3.7
+          - os: ubuntu-20.04
+            python: 3.8
+          - os: ubuntu-20.04
+            python: 3.9
+          - os: ubuntu-latest
+            python: 3.9
+          - os: ubuntu-latest
+            python: "pypy-3.7"
+          - os: ubuntu-latest
+            python: 3.9
+            tesseract5: true
+
+    env:
+      OS: ${{ matrix.os }}
+      PYTHON: ${{ matrix.python }}
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: "0" # 0=all, needed for setuptools-scm to resolve version tags
+
+      - uses: actions/setup-python@v2
+        name: Install Python
+        with:
+          python-version: ${{ matrix.python }}
+
+      - name: Install Tesseract 5
+        if: matrix.tesseract5
+        run: |
+          sudo add-apt-repository ppa:alex-p/tesseract-ocr-devel
+
+      - name: Install common packages
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y --no-install-recommends \
+            curl \
+            ghostscript \
+            img2pdf \
+            libffi-dev \
+            libsm6 libxext6 libxrender-dev \
+            pngquant \
+            poppler-utils \
+            tesseract-ocr \
+            tesseract-ocr-deu \
+            tesseract-ocr-eng \
+            tesseract-ocr-osd \
+            unpaper \
+            zlib1g
+
+      - name: Install Ubuntu 18.04 packages
+        if: matrix.os == 'ubuntu-18.04'
+        run: |
+          sudo apt-get install -y --no-install-recommends \
+            libexempi3
+
+      - name: Install Ubuntu 20.04 packages
+        if: matrix.os == 'ubuntu-20.04' || matrix.os == 'ubuntu-latest'
+        run: |
+          sudo apt-get install -y --no-install-recommends \
+            libexempi8
+
+      - name: Install Ubuntu packages for PyPy
+        if: startsWith(matrix.python, 'pypy')
+        run: |
+          sudo apt-get install -y --no-install-recommends \
+            libxml2-dev \
+            libxslt1-dev \
+            pypy3-dev
+
+      - name: Install Python packages
+        run: |
+          python -m pip install --upgrade pip wheel
+          python -m pip install .[test]
+
+      - name: Report versions
+        run: |
+          tesseract --version
+          gs --version
+          pngquant --version
+          unpaper --version
+          img2pdf --version
+
+      - name: Test
+        run: |
+          python -m pytest --cov-report xml --cov=ocrmypdf --cov=tests/ -n0 tests/
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v1
+        with:
+          files: ./coverage.xml
+          env_vars: OS,PYTHON
+
+  test_macos:
+    name: Test macOS
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-latest]
+        python: ["3.9"]
+
+    env:
+      OS: ${{ matrix.os }}
+      PYTHON: ${{ matrix.python }}
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: "0" # 0=all, needed for setuptools-scm to resolve version tags
+
+      - uses: actions/setup-python@v2
+        name: Install Python
+        with:
+          python-version: ${{ matrix.python }}
+
+      - name: Install Homebrew deps
+        run: |
+          brew update
+          brew install \
+            exempi \
+            ghostscript \
+            jbig2enc \
+            openjpeg \
+            pngquant \
+            tesseract
+
+      - name: Install Python packages
+        run: |
+          python -m pip install --upgrade pip wheel
+          python -m pip install .[test]
+
+      - name: Report versions
+        run: |
+          tesseract --version
+          gs --version
+          pngquant --version
+          img2pdf --version
+
+      - name: Test
+        run: |
+          python -m pytest --cov-report xml --cov=ocrmypdf --cov=tests/ -n0 tests/
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v1
+        with:
+          files: ./coverage.xml
+          env_vars: OS,PYTHON
+
+  test_windows:
+    name: Test Windows
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [windows-latest]
+        python: ["3.9"]
+
+    env:
+      OS: ${{ matrix.os }}
+      PYTHON: ${{ matrix.python }}
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: "0" # 0=all, needed for setuptools-scm to resolve version tags
+
+      - uses: actions/setup-python@v2
+        name: Install Python
+        with:
+          python-version: ${{ matrix.python }}
+
+      - name: Install system packages
+        run: |
+          choco install --yes --no-progress --pre tesseract
+          choco install --yes --no-progress ghostscript
+          choco install --yes --no-progress pngquant
+
+      - name: Install Python packages
+        run: |
+          python -m pip install --upgrade pip wheel
+          python -m pip install .[test]
+
+      - name: Test
+        run: |
+          python -m pytest --cov-report xml --cov=ocrmypdf --cov=tests/ -n0 tests/
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v1
+        with:
+          files: ./coverage.xml
+          env_vars: OS,PYTHON
+
+  wheel_sdist_linux:
+    name: Build sdist and wheels
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: "0" # 0=all, needed for setuptools-scm to resolve version tags
+
+      - uses: actions/setup-python@v2
+        name: Install Python
+        with:
+          python-version: "3.7"
+
+      - name: Make wheels and sdist
+        run: |
+          python -m pip install --upgrade pip wheel
+          python setup.py sdist
+          python setup.py bdist_wheel
+
+      - uses: actions/upload-artifact@v2
+        with:
+          path: |
+            ./dist/*.whl
+            ./dist/*.tar.gz
+
+  upload_pypi:
+    name: Deploy artifacts to PyPI
+    needs: [wheel_sdist_linux, test_linux, test_macos, test_windows]
+    runs-on: ubuntu-latest
+    if: github.event_name == 'push' && startsWith(github.event.ref, 'refs/tags/v')
+    steps:
+      - uses: actions/download-artifact@v2
+        with:
+          name: artifact
+          path: dist
+
+      - uses: pypa/gh-action-pypi-publish@master
+        with:
+          user: __token__
+          password: ${{ secrets.TOKEN_PYPI }}
+          # repository_url: https://test.pypi.org/legacy/
+
+  docker:
+    name: Build Docker images
+    needs: [wheel_sdist_linux, test_linux, test_macos, test_windows]
+    runs-on: ubuntu-latest
+    if: github.event_name != 'pull_request'
+    steps:
+      - name: Set image tag to release or branch
+        run: echo "DOCKER_IMAGE_TAG=${GITHUB_REF##*/}" >> $GITHUB_ENV
+
+      - name: If master, set to latest
+        run: echo 'DOCKER_IMAGE_TAG=latest' >> $GITHUB_ENV
+        if: env.DOCKER_IMAGE_TAG == 'master'
+
+      - name: Set Docker Hub repository to username
+        run: echo "DOCKER_REPOSITORY=jbarlow83" >> $GITHUB_ENV
+
+      - name: Set image name
+        run: echo "DOCKER_IMAGE_NAME=ocrmypdf" >> $GITHUB_ENV
+
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: "0" # 0=all, needed for setuptools-scm to resolve version tags
+
+      - name: Login to Docker Hub
+        uses: docker/login-action@v1
+        with:
+          username: jbarlow83
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+
+      - name: Set up Docker Buildx
+        id: buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Print image tag
+        run: echo "Building image ${DOCKER_REPOSITORY}/${DOCKER_IMAGE_NAME}:${DOCKER_IMAGE_TAG}"
+
+      - name: Build
+        run: |
+          docker buildx build \
+            --push \
+            --platform linux/arm64/v8,linux/amd64  \
+            --tag "${DOCKER_REPOSITORY}/${DOCKER_IMAGE_NAME}:${DOCKER_IMAGE_TAG}" \
+            --file .docker/Dockerfile .

.gitignore

@@ -1,17 +1,45 @@
-tmp/
-log/
-*.pyc
-tests/output/
-.ruffus_history.sqlite
-*.sublime-*
+# dotfiles
+.*
+!.coveragerc
+!.dockerignore
+!.git_archival.txt
+!.gitattributes
+!.gitignore
+!.pre-commit-config.yaml
+!.readthedocs.yaml
+!.github/
+!.docker/
+
+# Dev scratch
+*.ipynb
+**/*.pyc
 /*.pdf
+/*.qdf
+/*.png
+/scratch.py
+IDEAS
+log/
+tests/resources/private/
+tmp/
+venv*/
+/debug_tests.py
+*.traineddata
+/private
+/coverage.xml
+
+# Package building
+*.egg-info/
 build/
 dist/
-*.egg-info/
-venv/
-*/test/output
-bin/
-include/
-lib/
-pip-selfcheck.json
-pyvenv.cfg
+wheelhouse/
+pip-wheel-metadata/
+
+# Code coverage
+htmlcov/
+
+# Automatically generated files
+docs/_build/
+docs/_static/
+docs/_templates/
+docs/Makefile
+ocrmypdf/lib/_*.py

.pre-commit-config.yaml

@@ -0,0 +1,37 @@
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.0.1
+    hooks:
+      - id: check-case-conflict
+      - id: check-merge-conflict
+      - id: check-toml
+      - id: check-yaml
+      - id: debug-statements
+  - repo: https://github.com/pycqa/isort
+    rev: 5.9.3
+    hooks:
+      - id: isort
+        args: ["--profile", "black"]
+  - repo: https://github.com/psf/black
+    rev: 21.9b0
+    hooks:
+      - id: black
+        language_version: python
+  - repo: https://github.com/asottile/setup-cfg-fmt
+    rev: v1.19.0
+    hooks:
+      - id: setup-cfg-fmt
+  - repo: https://github.com/asottile/pyupgrade
+    rev: v2.29.0
+    hooks:
+      - id: pyupgrade
+        args: ["--py37-plus"]
+  - repo: https://github.com/pre-commit/mirrors-mypy
+    rev: v0.910-1
+    hooks:
+      - id: mypy
+        additional_dependencies:
+          - types-toml
+          - types-setuptools
+          - types-requests
+          - types-Pillow

.readthedocs.yaml

@@ -0,0 +1,22 @@
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+# Build documentation in the docs/ directory with Sphinx
+sphinx:
+  configuration: docs/conf.py
+
+# Optionally build your docs in additional formats such as PDF
+formats:
+  - pdf
+
+# Optionally set the version of Python and requirements required to build your docs
+python:
+  version: 3.7
+  install:
+    - method: pip
+      path: .
+      extra_requirements:
+        - docs

LICENSE

@@ -0,0 +1,373 @@
+Mozilla Public License Version 2.0
+==================================
+
+1. Definitions
+--------------
+
+1.1. "Contributor"
+    means each individual or legal entity that creates, contributes to
+    the creation of, or owns Covered Software.
+
+1.2. "Contributor Version"
+    means the combination of the Contributions of others (if any) used
+    by a Contributor and that particular Contributor's Contribution.
+
+1.3. "Contribution"
+    means Covered Software of a particular Contributor.
+
+1.4. "Covered Software"
+    means Source Code Form to which the initial Contributor has attached
+    the notice in Exhibit A, the Executable Form of such Source Code
+    Form, and Modifications of such Source Code Form, in each case
+    including portions thereof.
+
+1.5. "Incompatible With Secondary Licenses"
+    means
+
+    (a) that the initial Contributor has attached the notice described
+        in Exhibit B to the Covered Software; or
+
+    (b) that the Covered Software was made available under the terms of
+        version 1.1 or earlier of the License, but not also under the
+        terms of a Secondary License.
+
+1.6. "Executable Form"
+    means any form of the work other than Source Code Form.
+
+1.7. "Larger Work"
+    means a work that combines Covered Software with other material, in
+    a separate file or files, that is not Covered Software.
+
+1.8. "License"
+    means this document.
+
+1.9. "Licensable"
+    means having the right to grant, to the maximum extent possible,
+    whether at the time of the initial grant or subsequently, any and
+    all of the rights conveyed by this License.
+
+1.10. "Modifications"
+    means any of the following:
+
+    (a) any file in Source Code Form that results from an addition to,
+        deletion from, or modification of the contents of Covered
+        Software; or
+
+    (b) any new file in Source Code Form that contains any Covered
+        Software.
+
+1.11. "Patent Claims" of a Contributor
+    means any patent claim(s), including without limitation, method,
+    process, and apparatus claims, in any patent Licensable by such
+    Contributor that would be infringed, but for the grant of the
+    License, by the making, using, selling, offering for sale, having
+    made, import, or transfer of either its Contributions or its
+    Contributor Version.
+
+1.12. "Secondary License"
+    means either the GNU General Public License, Version 2.0, the GNU
+    Lesser General Public License, Version 2.1, the GNU Affero General
+    Public License, Version 3.0, or any later versions of those
+    licenses.
+
+1.13. "Source Code Form"
+    means the form of the work preferred for making modifications.
+
+1.14. "You" (or "Your")
+    means an individual or a legal entity exercising rights under this
+    License. For legal entities, "You" includes any entity that
+    controls, is controlled by, or is under common control with You. For
+    purposes of this definition, "control" means (a) the power, direct
+    or indirect, to cause the direction or management of such entity,
+    whether by contract or otherwise, or (b) ownership of more than
+    fifty percent (50%) of the outstanding shares or beneficial
+    ownership of such entity.
+
+2. License Grants and Conditions
+--------------------------------
+
+2.1. Grants
+
+Each Contributor hereby grants You a world-wide, royalty-free,
+non-exclusive license:
+
+(a) under intellectual property rights (other than patent or trademark)
+    Licensable by such Contributor to use, reproduce, make available,
+    modify, display, perform, distribute, and otherwise exploit its
+    Contributions, either on an unmodified basis, with Modifications, or
+    as part of a Larger Work; and
+
+(b) under Patent Claims of such Contributor to make, use, sell, offer
+    for sale, have made, import, and otherwise transfer either its
+    Contributions or its Contributor Version.
+
+2.2. Effective Date
+
+The licenses granted in Section 2.1 with respect to any Contribution
+become effective for each Contribution on the date the Contributor first
+distributes such Contribution.
+
+2.3. Limitations on Grant Scope
+
+The licenses granted in this Section 2 are the only rights granted under
+this License. No additional rights or licenses will be implied from the
+distribution or licensing of Covered Software under this License.
+Notwithstanding Section 2.1(b) above, no patent license is granted by a
+Contributor:
+
+(a) for any code that a Contributor has removed from Covered Software;
+    or
+
+(b) for infringements caused by: (i) Your and any other third party's
+    modifications of Covered Software, or (ii) the combination of its
+    Contributions with other software (except as part of its Contributor
+    Version); or
+
+(c) under Patent Claims infringed by Covered Software in the absence of
+    its Contributions.
+
+This License does not grant any rights in the trademarks, service marks,
+or logos of any Contributor (except as may be necessary to comply with
+the notice requirements in Section 3.4).
+
+2.4. Subsequent Licenses
+
+No Contributor makes additional grants as a result of Your choice to
+distribute the Covered Software under a subsequent version of this
+License (see Section 10.2) or under the terms of a Secondary License (if
+permitted under the terms of Section 3.3).
+
+2.5. Representation
+
+Each Contributor represents that the Contributor believes its
+Contributions are its original creation(s) or it has sufficient rights
+to grant the rights to its Contributions conveyed by this License.
+
+2.6. Fair Use
+
+This License is not intended to limit any rights You have under
+applicable copyright doctrines of fair use, fair dealing, or other
+equivalents.
+
+2.7. Conditions
+
+Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted
+in Section 2.1.
+
+3. Responsibilities
+-------------------
+
+3.1. Distribution of Source Form
+
+All distribution of Covered Software in Source Code Form, including any
+Modifications that You create or to which You contribute, must be under
+the terms of this License. You must inform recipients that the Source
+Code Form of the Covered Software is governed by the terms of this
+License, and how they can obtain a copy of this License. You may not
+attempt to alter or restrict the recipients' rights in the Source Code
+Form.
+
+3.2. Distribution of Executable Form
+
+If You distribute Covered Software in Executable Form then:
+
+(a) such Covered Software must also be made available in Source Code
+    Form, as described in Section 3.1, and You must inform recipients of
+    the Executable Form how they can obtain a copy of such Source Code
+    Form by reasonable means in a timely manner, at a charge no more
+    than the cost of distribution to the recipient; and
+
+(b) You may distribute such Executable Form under the terms of this
+    License, or sublicense it under different terms, provided that the
+    license for the Executable Form does not attempt to limit or alter
+    the recipients' rights in the Source Code Form under this License.
+
+3.3. Distribution of a Larger Work
+
+You may create and distribute a Larger Work under terms of Your choice,
+provided that You also comply with the requirements of this License for
+the Covered Software. If the Larger Work is a combination of Covered
+Software with a work governed by one or more Secondary Licenses, and the
+Covered Software is not Incompatible With Secondary Licenses, this
+License permits You to additionally distribute such Covered Software
+under the terms of such Secondary License(s), so that the recipient of
+the Larger Work may, at their option, further distribute the Covered
+Software under the terms of either this License or such Secondary
+License(s).
+
+3.4. Notices
+
+You may not remove or alter the substance of any license notices
+(including copyright notices, patent notices, disclaimers of warranty,
+or limitations of liability) contained within the Source Code Form of
+the Covered Software, except that You may alter any license notices to
+the extent required to remedy known factual inaccuracies.
+
+3.5. Application of Additional Terms
+
+You may choose to offer, and to charge a fee for, warranty, support,
+indemnity or liability obligations to one or more recipients of Covered
+Software. However, You may do so only on Your own behalf, and not on
+behalf of any Contributor. You must make it absolutely clear that any
+such warranty, support, indemnity, or liability obligation is offered by
+You alone, and You hereby agree to indemnify every Contributor for any
+liability incurred by such Contributor as a result of warranty, support,
+indemnity or liability terms You offer. You may include additional
+disclaimers of warranty and limitations of liability specific to any
+jurisdiction.
+
+4. Inability to Comply Due to Statute or Regulation
+---------------------------------------------------
+
+If it is impossible for You to comply with any of the terms of this
+License with respect to some or all of the Covered Software due to
+statute, judicial order, or regulation then You must: (a) comply with
+the terms of this License to the maximum extent possible; and (b)
+describe the limitations and the code they affect. Such description must
+be placed in a text file included with all distributions of the Covered
+Software under this License. Except to the extent prohibited by statute
+or regulation, such description must be sufficiently detailed for a
+recipient of ordinary skill to be able to understand it.
+
+5. Termination
+--------------
+
+5.1. The rights granted under this License will terminate automatically
+if You fail to comply with any of its terms. However, if You become
+compliant, then the rights granted under this License from a particular
+Contributor are reinstated (a) provisionally, unless and until such
+Contributor explicitly and finally terminates Your grants, and (b) on an
+ongoing basis, if such Contributor fails to notify You of the
+non-compliance by some reasonable means prior to 60 days after You have
+come back into compliance. Moreover, Your grants from a particular
+Contributor are reinstated on an ongoing basis if such Contributor
+notifies You of the non-compliance by some reasonable means, this is the
+first time You have received notice of non-compliance with this License
+from such Contributor, and You become compliant prior to 30 days after
+Your receipt of the notice.
+
+5.2. If You initiate litigation against any entity by asserting a patent
+infringement claim (excluding declaratory judgment actions,
+counter-claims, and cross-claims) alleging that a Contributor Version
+directly or indirectly infringes any patent, then the rights granted to
+You by any and all Contributors for the Covered Software under Section
+2.1 of this License shall terminate.
+
+5.3. In the event of termination under Sections 5.1 or 5.2 above, all
+end user license agreements (excluding distributors and resellers) which
+have been validly granted by You or Your distributors under this License
+prior to termination shall survive termination.
+
+************************************************************************
+*                                                                      *
+*  6. Disclaimer of Warranty                                           *
+*  -------------------------                                           *
+*                                                                      *
+*  Covered Software is provided under this License on an "as is"       *
+*  basis, without warranty of any kind, either expressed, implied, or  *
+*  statutory, including, without limitation, warranties that the       *
+*  Covered Software is free of defects, merchantable, fit for a        *
+*  particular purpose or non-infringing. The entire risk as to the     *
+*  quality and performance of the Covered Software is with You.        *
+*  Should any Covered Software prove defective in any respect, You     *
+*  (not any Contributor) assume the cost of any necessary servicing,   *
+*  repair, or correction. This disclaimer of warranty constitutes an   *
+*  essential part of this License. No use of any Covered Software is   *
+*  authorized under this License except under this disclaimer.         *
+*                                                                      *
+************************************************************************
+
+************************************************************************
+*                                                                      *
+*  7. Limitation of Liability                                          *
+*  --------------------------                                          *
+*                                                                      *
+*  Under no circumstances and under no legal theory, whether tort      *
+*  (including negligence), contract, or otherwise, shall any           *
+*  Contributor, or anyone who distributes Covered Software as          *
+*  permitted above, be liable to You for any direct, indirect,         *
+*  special, incidental, or consequential damages of any character      *
+*  including, without limitation, damages for lost profits, loss of    *
+*  goodwill, work stoppage, computer failure or malfunction, or any    *
+*  and all other commercial damages or losses, even if such party      *
+*  shall have been informed of the possibility of such damages. This   *
+*  limitation of liability shall not apply to liability for death or   *
+*  personal injury resulting from such party's negligence to the       *
+*  extent applicable law prohibits such limitation. Some               *
+*  jurisdictions do not allow the exclusion or limitation of           *
+*  incidental or consequential damages, so this exclusion and          *
+*  limitation may not apply to You.                                    *
+*                                                                      *
+************************************************************************
+
+8. Litigation
+-------------
+
+Any litigation relating to this License may be brought only in the
+courts of a jurisdiction where the defendant maintains its principal
+place of business and such litigation shall be governed by laws of that
+jurisdiction, without reference to its conflict-of-law provisions.
+Nothing in this Section shall prevent a party's ability to bring
+cross-claims or counter-claims.
+
+9. Miscellaneous
+----------------
+
+This License represents the complete agreement concerning the subject
+matter hereof. If any provision of this License is held to be
+unenforceable, such provision shall be reformed only to the extent
+necessary to make it enforceable. Any law or regulation which provides
+that the language of a contract shall be construed against the drafter
+shall not be used to construe this License against a Contributor.
+
+10. Versions of the License
+---------------------------
+
+10.1. New Versions
+
+Mozilla Foundation is the license steward. Except as provided in Section
+10.3, no one other than the license steward has the right to modify or
+publish new versions of this License. Each version will be given a
+distinguishing version number.
+
+10.2. Effect of New Versions
+
+You may distribute the Covered Software under the terms of the version
+of the License under which You originally received the Covered Software,
+or under the terms of any subsequent version published by the license
+steward.
+
+10.3. Modified Versions
+
+If you create software not governed by this License, and you want to
+create a new license for such software, you may create and use a
+modified version of this License if you rename the license and remove
+any references to the name of the license steward (except to note that
+such modified license differs from this License).
+
+10.4. Distributing Source Code Form that is Incompatible With Secondary
+Licenses
+
+If You choose to distribute Source Code Form that is Incompatible With
+Secondary Licenses under the terms of this version of the License, the
+notice described in Exhibit B of this License must be attached.
+
+Exhibit A - Source Code Form License Notice
+-------------------------------------------
+
+  This Source Code Form is subject to the terms of the Mozilla Public
+  License, v. 2.0. If a copy of the MPL was not distributed with this
+  file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+If it is not possible or desirable to put the notice in a particular
+file, then You may include the notice in a location (such as a LICENSE
+file in a relevant directory) where a recipient would be likely to look
+for such a notice.
+
+You may add additional accurate notices of copyright ownership.
+
+Exhibit B - "Incompatible With Secondary Licenses" Notice
+---------------------------------------------------------
+
+  This Source Code Form is "Incompatible With Secondary Licenses", as
+  defined by the Mozilla Public License, v. 2.0.

LICENSE.rst

@@ -1,20 +0,0 @@
-Copyright (c) 2013-2015, The OCRmyPDF Authors
-
-Permission is hereby granted, free of charge, to any person obtaining a
-copy of this software and associated documentation files (the
-"Software"), to deal in the Software without restriction, including
-without limitation the rights to use, copy, modify, merge, publish,
-distribute, sublicense, and/or sell copies of the Software, and to
-permit persons to whom the Software is furnished to do so, subject to
-the following conditions:
-
-The above copyright notice and this permission notice shall be included
-in all copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
-OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
-IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
-CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
-TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
-SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

MANIFEST.in

@@ -1 +0,0 @@
-recursive-exclude tests/output *

OCRmyPDF.sh

@@ -1,6 +0,0 @@
-#!/bin/sh
-##############################################################################
-# Copyright (c) 2013-14: fritz-hh from Github (https://github.com/fritz-hh)
-##############################################################################
-
-python3 -m ocrmypdf.main "$@"

README.md

@@ -0,0 +1,143 @@
+<img src="docs/images/logo.svg" width="240" alt="OCRmyPDF">
+
+[![Build Status](https://github.com/jbarlow83/OCRmyPDF/actions/workflows/build.yml/badge.svg)](https://github.com/jbarlow83/OCRmyPDF/actions/workflows/build.yml) [![PyPI version][pypi]](https://pypi.org/project/ocrmypdf/) ![Homebrew version][homebrew] ![ReadTheDocs][docs] ![Python versions][pyversions]
+
+[azure]: https://dev.azure.com/jim0585/ocrmypdf/_apis/build/status/jbarlow83.OCRmyPDF?branchName=master
+[travis]: https://travis-ci.org/jbarlow83/OCRmyPDF.svg?branch=master "Travis build status"
+[pypi]: https://img.shields.io/pypi/v/ocrmypdf.svg "PyPI version"
+[homebrew]: https://img.shields.io/homebrew/v/ocrmypdf.svg "Homebrew version"
+[docs]: https://readthedocs.org/projects/ocrmypdf/badge/?version=latest "RTD"
+[pyversions]: https://img.shields.io/pypi/pyversions/ocrmypdf "Supported Python versions"
+
+OCRmyPDF adds an OCR text layer to scanned PDF files, allowing them to be searched or copy-pasted.
+
+```bash
+ocrmypdf                      # it's a scriptable command line program
+   -l eng+fra                 # it supports multiple languages
+   --rotate-pages             # it can fix pages that are misrotated
+   --deskew                   # it can deskew crooked PDFs!
+   --title "My PDF"           # it can change output metadata
+   --jobs 4                   # it uses multiple cores by default
+   --output-type pdfa         # it produces PDF/A by default
+   input_scanned.pdf          # takes PDF input (or images)
+   output_searchable.pdf      # produces validated PDF output
+```
+
+[See the release notes for details on the latest changes](https://ocrmypdf.readthedocs.io/en/latest/release_notes.html).
+
+## Main features
+
+- Generates a searchable [PDF/A](https://en.wikipedia.org/?title=PDF/A) file from a regular PDF
+- Places OCR text accurately below the image to ease copy / paste
+- Keeps the exact resolution of the original embedded images
+- When possible, inserts OCR information as a "lossless" operation without disrupting any other content
+- Optimizes PDF images, often producing files smaller than the input file
+- If requested, deskews and/or cleans the image before performing OCR
+- Validates input and output files
+- Distributes work across all available CPU cores
+- Uses [Tesseract OCR](https://github.com/tesseract-ocr/tesseract) engine to recognize more than [100 languages](https://github.com/tesseract-ocr/tessdata)
+- Scales properly to handle files with thousands of pages
+- Battle-tested on millions of PDFs
+
+For details: please consult the [documentation](https://ocrmypdf.readthedocs.io/en/latest/).
+
+## Motivation
+
+I searched the web for a free command line tool to OCR PDF files: I found many, but none of them were really satisfying:
+
+- Either they produced PDF files with misplaced text under the image (making copy/paste impossible)
+- Or they did not handle accents and multilingual characters
+- Or they changed the resolution of the embedded images
+- Or they generated ridiculously large PDF files
+- Or they crashed when trying to OCR
+- Or they did not produce valid PDF files
+- On top of that none of them produced PDF/A files (format dedicated for long time storage)
+
+...so I decided to develop my own tool.
+
+## Installation
+
+Linux, Windows, macOS and FreeBSD are supported. Docker images are also available, for both x64 and ARM.
+
+| Operating system              | Install command               |
+| ----------------------------- | ------------------------------|
+| Debian, Ubuntu                | ``apt install ocrmypdf``      |
+| Windows Subsystem for Linux   | ``apt install ocrmypdf``      |
+| Fedora                        | ``dnf install ocrmypdf``      |
+| macOS                         | ``brew install ocrmypdf``     |
+| LinuxBrew                     | ``brew install ocrmypdf``     |
+| FreeBSD                       | ``pkg install py37-ocrmypdf`` |
+| Conda                         | ``conda install ocrmypdf``    |
+
+For everyone else, [see our documentation](https://ocrmypdf.readthedocs.io/en/latest/installation.html) for installation steps.
+
+## Languages
+
+OCRmyPDF uses Tesseract for OCR, and relies on its language packs. For Linux users, you can often find packages that provide language packs:
+
+```bash
+# Display a list of all Tesseract language packs
+apt-cache search tesseract-ocr
+
+# Debian/Ubuntu users
+apt-get install tesseract-ocr-chi-sim  # Example: Install Chinese Simplified language pack
+
+# Arch Linux users
+pacman -S tesseract-data-eng tesseract-data-deu # Example: Install the English and German language packs
+
+# brew macOS users
+brew install tesseract-lang
+```
+
+You can then pass the `-l LANG` argument to OCRmyPDF to give a hint as to what languages it should search for. Multiple languages can be requested.
+
+OCRmyPDF supports Tesseract 4.0 and the beta versions of Tesseract 5.0. It will
+automatically use whichever version it finds first on the `PATH` environment
+variable. On Windows, if `PATH` does not provide a Tesseract binary, we use
+the highest version number that is installed according to the Windows Registry.
+
+## Documentation and support
+
+Once OCRmyPDF is installed, the built-in help which explains the command syntax and options can be accessed via:
+
+```bash
+ocrmypdf --help
+```
+
+Our [documentation is served on Read the Docs](https://ocrmypdf.readthedocs.io/en/latest/index.html).
+
+Please report issues on our [GitHub issues](https://github.com/jbarlow83/OCRmyPDF/issues) page, and follow the issue template for quick response.
+
+## Requirements
+
+In addition to the required Python version (3.7+), OCRmyPDF requires external program installations of Ghostscript and Tesseract OCR. OCRmyPDF is pure Python, and runs on pretty much everything: Linux, macOS, Windows and FreeBSD.
+
+## Press & Media
+
+- [Going paperless with OCRmyPDF](https://medium.com/@ikirichenko/going-paperless-with-ocrmypdf-e2f36143f46a)
+- [Converting a scanned document into a compressed searchable PDF with redactions](https://medium.com/@treyharris/converting-a-scanned-document-into-a-compressed-searchable-pdf-with-redactions-63f61c34fe4c)
+- [c't 1-2014, page 59](https://heise.de/-2279695): Detailed presentation of OCRmyPDF v1.0 in the leading German IT magazine c't
+- [heise Open Source, 09/2014: Texterkennung mit OCRmyPDF](https://heise.de/-2356670)
+- [heise Durchsuchbare PDF-Dokumente mit OCRmyPDF erstellen](https://www.heise.de/ratgeber/Durchsuchbare-PDF-Dokumente-mit-OCRmyPDF-erstellen-4607592.html)
+- [Excellent Utilities: OCRmyPDF](https://www.linuxlinks.com/excellent-utilities-ocrmypdf-add-ocr-text-layer-scanned-pdfs/)
+- [LinuxUser Texterkennung mit OCRmyPDF und Scanbd automatisieren](https://www.linux-community.de/ausgaben/linuxuser/2021/06/texterkennung-mit-ocrmypdf-und-scanbd-automatisieren/)
+
+## Business enquiries
+
+OCRmyPDF would not be the software that it is today without companies and users choosing to provide support for feature development and consulting enquiries. We are happy to discuss all enquiries, whether for extending the existing feature set, or integrating OCRmyPDF into a larger system.
+
+## License
+
+The OCRmyPDF software is licensed under the Mozilla Public License 2.0
+(MPL-2.0). This license permits integration of OCRmyPDF with other code,
+included commercial and closed source, but asks you to publish source-level
+modifications you make to OCRmyPDF.
+
+Some components of OCRmyPDF have other licenses, as noted in those files and the
+``debian/copyright`` file. Most files in ``misc/`` use the MIT license, and the
+documentation and test files are generally licensed under Creative Commons
+ShareAlike 4.0 (CC-BY-SA 4.0).
+
+## Disclaimer
+
+The software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

README.rst

@@ -1,171 +0,0 @@
-OCRmyPDF
-========
-
-OCRmyPDF adds an OCR text layer to scanned PDF files, allowing them to
-be searched.
-
-Main features
--------------
-
--  Generates a searchable
-   `PDF/A <https://en.wikipedia.org/?title=PDF/A>`__ file from a regular PDF
-   only containing images
--  Places OCRed text accurately below the image to ease copy / paste
--  Keeps the exact resolution of the original embedded images
-
-   -  or if requested oversamples the images before OCRing so as to get
-      better results
-
--  When possible, copies input images directly to output without transcoding them,
-   to preserve image quality
--  Keeps file size about the same
--  If requested deskews and/or cleans the image before performing OCR
--  Validates input and output files
--  Provides debug mode to enable easy verification of the OCR results
--  Processes several pages in parallel when more than one CPU core is
-   available
--  Uses Tesseract OCR engine
-
-For details: please consult the `release notes <RELEASE_NOTES.rst>`__
-
-Motivation
-----------
-
-I searched the web for a free command line tool to OCR PDF files on
-Linux/UNIX: I found many, but none of them were really satisfying.
-
--  Either they produced PDF files with misplaced text under the image (making copy/paste impossible) 
--  Or they did not display correctly some escaped HTML characters located in the hOCR file produced by the OCR engine 
--  Or they changed the resolution of the embedded images
--  Or they generated PDF files having a ridiculous big size
--  Or they crashed when trying to OCR some of my PDF files
--  Or they did not produce valid PDF files (even though they were readable with my current PDF reader)
--  On top of that none of them produced PDF/A files (format dedicated for long time storage)
-
-... so I decided to develop my own tool (using various existing scripts
-as an inspiration)
-
-Installation
-------------
-
-Download OCRmyPDF here: https://github.com/fritz-hh/OCRmyPDF/releases
-
-You can install it to a Python virtual environment or system-wide. 
-
-
-Installing dependencies on Mac OS X Yosemite
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-If it's not already present, `install Homebrew <http://brew.sh/>`__
-
-Update Homebrew::
-
-   brew update
-   brew upgrade
-   
-Install the required Homebrew packages, if any are missing::
-
-   brew install libpng openjpeg jbig2dec     # image libraries
-   brew install qpdf
-   brew install ghostscript
-   brew install python3
-   brew install libxml2
-   brew install leptonica
-   brew install tesseract
-   
-It is also recommended that install Pillow and confirm it can read and write JPEG and PNG files::
-
-   pip3 install --upgrade pip
-   pip3 install --upgrade pillow
-
-To test that your dependencies are working, try this command::
-
-   python3 -c "from PIL import Image; im = Image.new('1', (1, 1)); im.save('test.png'); im.save('test.jpg')"
-
-
-Installing dependencies on Ubuntu 14.04 LTS
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-Update apt-get::
-
-   sudo apt-get update
-   sudo apt-get upgrade
-   
-Install dependencies::
-
-   sudo apt-get install \
-      zlib1g-dev \
-      libjpeg-dev \
-      libxml2 \
-      tesseract-ocr \
-      qpdf \
-      unpaper \
-      python3-pip \
-      python3-pil \
-      python3-pytest \
-      python3-reportlab
-      
-Installing HEAD revision from sources
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-To install the HEAD revision from sources in development mode::
-
-   git clone -b master https://github.com/fritz-hh/OCRmyPDF.git
-   cd OCRmyPDF
-   pip3 install -e .
-   
-On certain Linux/UNIX platforms such as Ubuntu, you may need to use 
-run the install command as superuser::
-
-   sudo pip3 install -e .
-   
-Note that this will alter your system's Python distribution. If you prefer 
-to not install as superuser, you can install the package in a Python virtual environment::
-
-   git clone -b master https://github.com/fritz-hh/OCRmyPDF.git
-   pyvenv venv
-   source venv/bin/activate
-   cd OCRmyPDF
-   pip3 install -e .
-
-If your platform does not have ``pip3``, make sure that Python 3.4+ and the `pip` 
-package are installed.
-
-To run the program::
-   
-   ocrmypdf --help
-
-If not yet installed, the script will notify you about dependencies that
-need to be installed. The script requires specific versions of the
-dependencies. Older version than the ones mentioned in the release notes
-are likely not to be compatible to OCRmyPDF.
-
-Support
--------
-
-In case you detect an issue, please:
-
--  Check if your issue is already known
--  If no problem report exists on github, please create one here:
-   https://github.com/fritz-hh/OCRmyPDF/issues
--  Describe your problem thoroughly
--  Append the console output of the script when running the debug mode
-   (-v 1 option)
--  If possible provide your input PDF file as well as the content of the
-   temporary folder (using a file sharing service like
-   www.file-upload.net)
-
-Press & Media
--------------
-
--  `c't 1-2014, page 59 <http://www.heise.de/ct/inhalt/2014/1/58/>`__:
-   Detailed presentation of OCRmyPDF v1.0 in the leading German IT
-   magazine c't
--  `heise Open Source, 09/2014: Texterkennung mit
-   OCRmyPDF <http://www.heise.de/-2356670>`__
-
-Disclaimer
-----------
-
-The software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
-CONDITIONS OF ANY KIND, either express or implied.

RELEASE_NOTES.rst

@@ -1,487 +0,0 @@
-RELEASE NOTES
-=============
-
-Please always read this file before installing the package
-
-Download software here: https://github.com/fritz-hh/OCRmyPDF/tags
-
-v3.0:
-=====
-
-New features
-------------
-
--  Easier installation with Python's package manager 
--  Eliminated many external dependencies, so it's easier to setup
--  Now installs ``ocrmypdf`` to ``/usr/local/bin`` or equivalent for system-wide
-   access and easier typing
--  Improved command line syntax and usage help (``--help``)
--  Tesseract 3.03 PDF page renderning can be used instead for better positioning
-   of recognized text (``--pdf-renderer tesseract``)
--  PDF metadata (title, author, keywords) are now transferred to the 
-   output PDF
--  PDF metadata can also be set from the command line (``--title``, etc.)
--  Added test cases to confirm everything is working
--  Added option to skip extremely large pages that take too long to OCR and are 
-   often not OCRable (e.g. large scanned maps or diagrams); other pages are still
-   processed (``--skip-big``)
--  Added option to kill Tesseract OCR process if it seems to be taking too long on
-   a page, while still processing other pages (``--tesseract-timeout``)
-
-Changes
--------
-
--  New, robust rewrite in Python 3.4+ with ruffus_ pipelines
--  Now uses Ghostscript 9.14's improved color conversion model to preserve PDF colors
--  All "tasks" in the pipeline can be executed in parallel on any
-   available CPUs, increasing performance
--  The ``-o DPI`` argument has been phased out, in favor of ``--oversample DPI``, in
-   case we need ``-o OUTPUTFILE`` in the future
--  Removed several dependencies, so it's easier to install.  We no 
-   longer use:
-   
-   - GNU parallel_
-   - ImageMagick_
-   - Python 2.7
-   - Poppler
-   - MuPDF_ tools
-   - shell scripts
-   - Java and JHOVE_
-
--  Some new external dependencies are required or optional, compared to v2.x:
-
-   - Ghostscript 9.14+
-   - qpdf_ 5.0.0+
-   - Unpaper_ 6.1 (optional)
-   - some automatically managed Python packages
-  
-.. _ruffus: http://www.ruffus.org.uk/index.html
-.. _parallel: https://www.gnu.org/software/parallel/
-.. _ImageMagick: http://www.imagemagick.org/script/index.php
-.. _MuPDF: http://mupdf.com/docs/
-.. _qpdf: http://qpdf.sourceforge.net/
-.. _Unpaper: https://github.com/Flameeyes/unpaper
-.. _JHOVE: http://jhove.sourceforge.net/
-
-Release candidates
-------------------
-
--  rc5:
-
-   - dropped Java and JHOVE in favour of qpdf
-   - improved command line error output
-   - additional tests and bug fixes
-   - tested on Ubuntu 14.04 LTS
-
--  rc4:
-
-   - dropped MuPDF in favour of qpdf
-   - fixed some installer issues and errors in installation instructions
-   - improve performance: run Ghostscript with multithreaded rendering
-   - improve performance: use multiple cores by default
-   - bug fix: checking for wrong exception on process timeout 
-
--  rc3: skipping version number intentionally to avoid confusion with Tesseract
--  rc2: first release for public testing to test-PyPI, Github
--  rc1: testing release process
-
-Compatibility notes
--------------------
-
--  ``./OCRmyPDF.sh`` script is still available for now
--  Stacking the verbosity option like ``-vvv`` is no longer supported
-
--  The configuration file ``config.sh`` has been removed.  Instead, you can
-   feed a file to the arguments for common settings:
-
-::
-
-   ocrmypdf input.pdf output.pdf @settings.txt
-
-where ``settings.txt`` contains *one argument per line*, for example:
-
-::
-
-   -l 
-   deu 
-   --author 
-   A. Merkel 
-   --pdf-renderer 
-   tesseract
-
-
-Fixes
------
-
--  Handling of filenames containing spaces: fixed
-
-Notes
------
-
--  Some dependencies may work with lower versions than tested, so try
-   overriding dependencies if they are "in the way" to see if they work.
-
-
-v2.2-stable (2014-09-29):
-=========================
-
-New features
-------------
-
-- None
-
-Changes
--------
-
-- Update to jhove v1.11
-- Request the python library reportlab v3.0 or newer (So that we could remove a patch to the previous version of reportlab leading to issues for some users)
-
-Fixes
------
-
-- Fix bug on Mac OS X (resolution of simlink to OCRmyPDF.sh script) (thanks to jbarlow83)
-- Check if the input pdf file exists before to continue
-
-Tested with
------------
-
-- Operating system: FreeBSD 9.2
-- Dependencies:
-
-   - parallel 20140822
-   - poppler-utils 0.24.5
-   - ImageMagick 6.8.9-4 2014-09-17
-   - Unpaper 0.3
-   - tesseract 3.02.02
-   - Python 2.7.8
-   - ghostcript (gs): 9.06
-   - java: openjdk version "1.7.0_65"
-
-
-v2.1-stable (2014-09-20):
-=========================
-
-New features
-------------
-
--  None
-
-Changes
--------
-
--  None
-
-Fixes
------
-
--  Allow execution via simlink
--  Add support for tesseract 3.03
--  Add support for newer version of reportlab
--  Lowered minimum version of gnu parallel
--  Various typo
-
-Tested with
------------
-
--  Operating system: FreeBSD 9.1
--  Dependencies:
--  parallel 20130222
--  poppler-utils 0.22.2
--  ImageMagick 6.8.0-7 2013-03-30
--  Unpaper 0.3
--  tesseract 3.02.02
--  Python 2.7.3
--  ghoscript (gs): 9.06
--  java: openjdk version "1.7.0\_17"
-
-v2.0-stable (2014-01-25):
-=========================
-
-New features
-------------
-
--  Check if the language(s) passed using the -l option is supported by
-   tesseract (fixes #60)
-
-Changes
--------
-
--  Allow OCRmyPDF to be used with tesseract 3.02.01, even though OCR
-   might fail for few PDF file (see issue #28). Rationale: For some
-   linux distribution, no newer version than tesseract 3.02.01 is
-   available
-
-Fixes
------
-
--  More robust algorithm for checking the version of the installed
-   tesseract package
-
-Tested with
------------
-
--  Operating system: FreeBSD 9.1
--  Dependencies:
--  parallel 20130222
--  poppler-utils 0.22.2
--  ImageMagick 6.8.0-7 2013-03-30
--  Unpaper 0.3
--  tesseract 3.02.02
--  Python 2.7.3
--  ghoscript (gs): 9.06
--  java: openjdk version "1.7.0\_17"
-
-v2.0-rc2 (2014-01-16):
-======================
-
-New features
-------------
-
--  None
-
-Changes
--------
-
--  Size reduction of final PDF file: (fixes #50)
--  Support for monochrome (Black&White) images (massive size reduction
-   in final PDF: >80%)
--  Reduced size of grayscale images (by 13% on test PDF file)
--  Preventing fi, fl ligatures does not require anymore to pass an
-   additional config file to tesseract using the -C option (fixes #58)
--  Location of temporary folder according to content of environment
-   variable TMPDIR.
--  Dependency to pdftk removed
--  Check for compatible versions of dependencies: (fixes #51)
--  parallel and tesseract
--  python libraries reportlab and lxml
-
-Fixes
------
-
--  Improved portability with various shells (dash, bash, tcsh) and OS
-   (FreeBSD, MAC OSX, Linux) (fixes #59)
--  Corrected bug in case the input PDF file contains a space character
-   (fixes #48)
--  Prevent spurious error message in case there is no image in a PDF
-   page
--  Prevent collision of temporary folder names (fixes #57)
-
-Tested with
------------
-
--  Operating system: FreeBSD 9.1
--  Dependencies:
--  parallel 20130222
--  poppler-utils 0.22.2
--  ImageMagick 6.8.0-7 2013-03-30
--  Unpaper 0.3
--  tesseract 3.02.02
--  Python 2.7.3
--  ghoscript (gs): 9.06
--  java: openjdk version "1.7.0\_17"
-
-v2.0-rc1 (2014-01-07):
-======================
-
-New features
-------------
-
--  Huge performance improvement on machines having multiple CPU/cores
-   (processing of several pages concurrently) (fixes #18)
--  By default prevent from processing a PDF file already containing
-   fonts (i.e. text)(it can be overridden with the -f flag) (fixes #16)
--  Warn if the resolution is too low to get reasonable OCR results
-   (fixes #37)
--  New option (-o) to perform automatic oversampling if the image
-   resolution is too low. This can improve OCR results.
--  Warn if using a tesseract version older than v3.02.02 (as older
-   versions are known to produce invalid output) (fixes #41)
--  Echo version of the installed dependencies (e.g. tesseract) in debug
-   mode in order to ease support (fixes #35)
--  Echo the arguments passed to the script in debug mode to ease support
-
-Changes
--------
-
--  In debug mode: The debug page is now placed after the respective
-   "normal" page
--  Reduced disk space usage in temporary folder if -d (deskew) or -c
-   (cleanup) options are not selected
--  New file src/config.sh containing various configuration parameters
--  Documentation of the tesseract config file "tess-cfg/no\_ligature"
-   improved
--  Improved consistency of the temporary file names
-
-Fixes
------
-
--  Improved robustness:
--  in case vertical resolution differs from horizontal resolution (fixes
-   #38)
--  in case a PDF page contains more than one image (fixes #36)
--  Fix a problem occurring if python 3 is the standard interpreter
-   (fixes #33)
--  Fix a problem occurring if the input PDF file contains special
-   characters like "#" (fixes #34)
-
-Tested with
------------
-
--  Operating system: FreeBSD 9.1
--  Dependencies:
--  parallel 20130222
--  poppler-utils 0.22.2
--  ImageMagick 6.8.0-7 2013-03-30
--  Unpaper 0.3
--  tesseract 3.02.02
--  Python 2.7.3
--  pdftk 1.45
--  ghoscript (gs): 9.06
--  java: openjdk version "1.7.0\_17"
-
-v1.1-stable (2014-01-06):
-=========================
-
-New features
-------------
-
--  N/A
-
-Changes
--------
-
--  N/A
-
-Fixes
------
-
--  Fixed syntax error (bashism) leading to an error message on certain
-   systems (fixes #42)
-
-Tested with
------------
-
--  Operating system: FreeBSD 9.1
--  Dependencies:
--  poppler-utils 0.22.2
--  ImageMagick 6.8.0-7 2013-03-30
--  Unpaper 0.3
--  tesseract 3.02.02
--  Python 2.7.3
--  pdftk 1.45
--  ghoscript (gs): 9.06
--  java: openjdk version "1.7.0\_17"
-
-v1.0-stable (2013-05-06):
-=========================
-
-New features
-------------
-
--  In debug mode: compute and echo time required for processing (fixes
-   #26)
-
-Changes
--------
-
--  Removed feature to add metadata in final pdf file (because it lead to
-   to final PDF file that does not comply to the PDF/A-1 format)
--  Removed feature to set same owner & permissions in final PDF file
-   than in input file
--  Removed many unused jhove files (e.g. documentation, \*.java and
-   \*.class files)
-
-Fixes
------
-
--  Correction to handle correctly path and input PDF files having spaces
-   (fixes #31)
--  Resolutions (x/y) that are nearly equal are now supported (fixes #25)
--  Fix compatibility issue with Ubuntu server 12.04 / Ubuntu server
-   10.04 / Linux Mint 13 Maya and probably other Linux distributions
-   (fixes #27)
--  Commit missing jhove files (\*.jar mainly) due to wrong .gitignore
-
-Tested with
------------
-
--  Operating system: FreeBSD 9.1
--  Dependencies:
--  poppler-utils 0.22.2
--  ImageMagick 6.8.0-7 2013-03-30
--  Unpaper 0.3
--  tesseract 3.02.02
--  Python 2.7.3
--  pdftk 1.45
--  ghoscript (gs): 9.06
--  java: openjdk version "1.7.0\_17"
-
-v1.0-rc2 (2013-04-29):
-======================
-
-New features
-------------
-
--  Keep temporary files if debug mode is set (fixes #22)
--  Set same owner & permissions in final PDF file than in input file
-   (fixes #9)
--  Added metadata in final pdf file (fixes #4)
-
-Changes
--------
-
--  N/A
-
-Fixes
------
-
--  Fixed wrong image cropping when deskew option is activated
--  Exit with error message if page size is not found in hocr file (fixes
-   #21)
--  Various minor fixes in log messages
-
-Tested with
------------
-
--  Operating system: FreeBSD 9.1
--  Dependencies:
--  poppler-utils 0.22.2
--  ImageMagick 6.8.0-7 2013-03-30
--  Unpaper 0.3
--  tesseract 3.02.02
--  Python 2.7.3
--  pdftk 1.45
--  ghoscript (gs): 9.06
--  java: openjdk version "1.7.0\_17"
-
-v1.0-rc1 (2013-04-26):
-======================
-
-New features
-------------
-
--  First release candidate
-
-Changes
--------
-
--  N/A
-
-Fixes
------
-
--  N/A
-
-Tested with
------------
-
--  Operating system: FreeBSD 9.1
--  Dependencies:
--  poppler-utils 0.22.2
--  ImageMagick 6.8.0-7 2013-03-30
--  Unpaper 0.3
--  tesseract 3.02.02
--  Python 2.7.3
--  pdftk 1.45
--  ghoscript (gs): 9.06
--  java: openjdk version "1.7.0\_17"

docs/advanced.rst

@@ -0,0 +1,344 @@
+=================
+Advanced features
+=================
+
+Control of unpaper
+==================
+
+OCRmyPDF uses ``unpaper`` to provide the implementation of the
+``--clean`` and ``--clean-final`` arguments.
+`unpaper <https://github.com/Flameeyes/unpaper/blob/master/doc/basic-concepts.md>`__
+provides a variety of image processing filters to improve images.
+
+By default, OCRmyPDF uses only ``unpaper`` arguments that were found to
+be safe to use on almost all files without having to inspect every page
+of the file afterwards. This is particularly true when only ``--clean``
+is used, since that instructs OCRmyPDF to only clean the image before
+OCR and not the final image.
+
+However, if you wish to use the more aggressive options in ``unpaper``,
+you may use ``--unpaper-args '...'`` to override the OCRmyPDF's defaults
+and forward other arguments to unpaper. This option will forward
+arguments to ``unpaper`` without any knowledge of what that program
+considers to be valid arguments. The string of arguments must be quoted
+as shown in the examples below. No filename arguments may be included.
+OCRmyPDF will assume it can append input and output filename of
+intermediate images to the ``--unpaper-args`` string.
+
+In this example, we tell ``unpaper`` to expect two pages of text on a
+sheet (image), such as occurs when two facing pages of a book are
+scanned. ``unpaper`` uses this information to deskew each independently
+and clean up the margins of both.
+
+.. code-block:: bash
+
+    ocrmypdf --clean --clean-final --unpaper-args '--layout double' input.pdf output.pdf
+    ocrmypdf --clean --clean-final --unpaper-args '--layout double --no-noisefilter' input.pdf output.pdf
+
+.. warning::
+
+   Some ``unpaper`` features will reposition text within the image.
+   ``--clean-final`` is recommended to avoid this issue.
+
+.. warning::
+
+   Some ``unpaper`` features cause multiple input or output files to be
+   consumed or produced. OCRmyPDF requires ``unpaper`` to consume one
+   file and produce one file. An deviation from that condition will
+   result in errors.
+
+.. note::
+
+   ``unpaper`` uses uncompressed PBM/PGM/PPM files for its intermediate
+   files. For large images or documents, it can take a lot of temporary
+   disk space.
+
+Control of OCR options
+======================
+
+OCRmyPDF provides many features to control the behavior of the OCR
+engine, Tesseract.
+
+When OCR is skipped
+-------------------
+
+If a page in a PDF seems to have text, by default OCRmyPDF will exit
+without modifying the PDF. This is to ensure that PDFs that were
+previously OCRed or were "born digital" rather than scanned are not
+processed.
+
+If ``--skip-text`` is issued, then no OCR will be performed on pages
+that already have text. The page will be copied to the output. This may
+be useful for documents that contain both "born digital" and scanned
+content, or to use OCRmyPDF to normalize and convert to PDF/A regardless
+of their contents.
+
+If ``--redo-ocr`` is issued, then a detailed text analysis is performed.
+Text is categorized as either visible or invisible. Invisible text (OCR)
+is stripped out. Then an image of each page is created with visible text
+masked out. The page image is sent for OCR, and any additional text is
+inserted as OCR. If a file contains a mix of text and bitmap images that
+contain text, OCRmyPDF will locate the additional text in images without
+disrupting the existing text.
+
+If ``--force-ocr`` is issued, then all pages will be rasterized to
+images, discarding any hidden OCR text, and rasterizing any printable
+text. This is useful for redoing OCR, for fixing OCR text with a damaged
+character map (text is selectable but not searchable), and destroying
+redacted information. Any forms and vector graphics will be rasterized
+as well.
+
+Time and image size limits
+--------------------------
+
+By default, OCRmyPDF permits tesseract to run for three minutes (180
+seconds) per page. This is usually more than enough time to find all
+text on a reasonably sized page with modern hardware.
+
+If a page is skipped, it will be inserted without OCR. If preprocessing
+was requested, the preprocessed image layer will be inserted.
+
+If you want to adjust the amount of time spent on OCR, change
+``--tesseract-timeout``. You can also automatically skip images that
+exceed a certain number of megapixels with ``--skip-big``. (A 300 DPI,
+8.5×11" page is 8.4 megapixels.)
+
+.. code-block:: bash
+
+    # Allow 300 seconds for OCR; skip any page larger than 50 megapixels
+    ocrmypdf --tesseract-timeout 300 --skip-big 50 bigfile.pdf output.pdf
+
+Overriding default tesseract
+----------------------------
+
+OCRmyPDF checks the system ``PATH`` for the ``tesseract`` binary.
+
+Some relevant environment variables that influence Tesseract's behavior
+include:
+
+.. envvar:: TESSDATA_PREFIX
+
+   Overrides the path to Tesseract's data files. This can allow
+   simultaneous installation of the "best" and "fast" training data
+   sets. OCRmyPDF does not manage this environment variable.
+
+.. envvar:: OMP_THREAD_LIMIT
+
+   Controls the number of threads Tesseract will use. OCRmyPDF will
+   manage this environment variable if it is not already set.
+
+For example, if you have a development build of Tesseract don't wish to
+use the system installation, you can launch OCRmyPDF as follows:
+
+.. code-block:: bash
+
+    env \
+        PATH=/home/user/src/tesseract/api:$PATH \
+        TESSDATA_PREFIX=/home/user/src/tesseract \
+        ocrmypdf input.pdf output.pdf
+
+In this example ``TESSDATA_PREFIX`` is required to redirect Tesseract to
+an alternate folder for its "tessdata" files.
+
+Overriding other support programs
+---------------------------------
+
+In addition to tesseract, OCRmyPDF uses the following external binaries:
+
+-  ``gs`` (Ghostscript)
+-  ``unpaper``
+-  ``pngquant``
+-  ``jbig2``
+
+In each case OCRmyPDF will search the ``PATH`` environment variable to
+locate the binaries.
+
+Changing tesseract configuration variables
+------------------------------------------
+
+You can override tesseract's default `control
+parameters <https://github.com/tesseract-ocr/tesseract/wiki/ControlParams>`__
+with a configuration file.
+
+As an example, this configuration will disable Tesseract's dictionary
+for current language. Normally the dictionary is helpful for
+interpolating words that are unclear, but it may interfere with OCR if
+the document does not contain many words (for example, a list of part
+numbers).
+
+Create a file named "no-dict.cfg" with these contents:
+
+::
+
+    load_system_dawg 0
+    language_model_penalty_non_dict_word 0
+    language_model_penalty_non_freq_dict_word 0
+
+then run ocrmypdf as follows (along with any other desired arguments):
+
+.. code-block:: bash
+
+    ocrmypdf --tesseract-config no-dict.cfg input.pdf output.pdf
+
+.. warning::
+
+   Some combinations of control parameters will break Tesseract or break
+   assumptions that OCRmyPDF makes about Tesseract's output.
+
+Changing the PDF renderer
+=========================
+
+rasterizing
+  Converting a PDF to an image for display.
+
+rendering
+  Creating a new PDF from other data (such as an existing PDF).
+
+OCRmyPDF has these PDF renderers: ``sandwich`` and ``hocr``. The
+renderer may be selected using ``--pdf-renderer``. The default is
+``auto`` which lets OCRmyPDF select the renderer to use. Currently,
+``auto`` always selects ``sandwich``.
+
+The ``sandwich`` renderer
+-------------------------
+
+The ``sandwich`` renderer uses Tesseract's new text-only PDF feature,
+which produces a PDF page that lays out the OCR in invisible text. This
+page is then "sandwiched" onto the original PDF page, allowing lossless
+application of OCR even to PDF pages that contain other vector objects.
+
+Currently this is the best renderer for most uses, however it is
+implemented in Tesseract so OCRmyPDF cannot influence it. Currently some
+problematic PDF viewers like Mozilla PDF.js and macOS Preview have
+problems with segmenting its text output, and
+mightrunseveralwordstogether.
+
+When image preprocessing features like ``--deskew`` are used, the
+original PDF will be rendered as a full page and the OCR layer will be
+placed on top.
+
+The ``hocr`` renderer
+---------------------
+
+The ``hocr`` renderer works with older versions of Tesseract. The image
+layer is copied from the original PDF page if possible, avoiding
+potentially lossy transcoding or loss of other PDF information. If
+preprocessing is specified, then the image layer is a new PDF.
+
+Unlike ``sandwich`` this renderer is implemented within OCRmyPDF; anyone
+looking to customize how OCR is presented should look here. A major
+disadvantage of this renderer is it not capable of correctly handling
+text outside the Latin alphabet (specifically, it supports the ISO 8859-1
+character). Pull requests to improve the situation are welcome.
+
+Currently, this renderer has the best compatibility with Mozilla's
+PDF.js viewer.
+
+This works in all versions of Tesseract.
+
+The ``tesseract`` renderer
+--------------------------
+
+The ``tesseract`` renderer was removed. OCRmyPDF's new approach to text
+layer grafting makes it functionally equivalent to ``sandwich``.
+
+Return code policy
+==================
+
+OCRmyPDF writes all messages to ``stderr``. ``stdout`` is reserved for
+piping output files. ``stdin`` is reserved for piping input files.
+
+The return codes generated by the OCRmyPDF are considered part of the
+stable user interface. They may be imported from
+``ocrmypdf.exceptions``.
+
+.. list-table:: Return codes
+    :widths: 5 35 60
+    :header-rows: 1
+
+    *	- Code
+        - Name
+        - Interpretation
+    *	- 0
+        - ``ExitCode.ok``
+        - Everything worked as expected.
+    *	- 1
+        - ``ExitCode.bad_args``
+        - Invalid arguments, exited with an error.
+    *	- 2
+        - ``ExitCode.input_file``
+        - The input file does not seem to be a valid PDF.
+    *	- 3
+        - ``ExitCode.missing_dependency``
+        - An external program required by OCRmyPDF is missing.
+    *	- 4
+        - ``ExitCode.invalid_output_pdf``
+        - An output file was created, but it does not seem to be a valid PDF. The file will be available.
+    *	- 5
+        - ``ExitCode.file_access_error``
+        - The user running OCRmyPDF does not have sufficient permissions to read the input file and write the output file.
+    *	- 6
+        - ``ExitCode.already_done_ocr``
+        - The file already appears to contain text so it may not need OCR. See output message.
+    *	- 7
+        - ``ExitCode.child_process_error``
+        - An error occurred in an external program (child process) and OCRmyPDF cannot continue.
+    *	- 8
+        - ``ExitCode.encrypted_pdf``
+        - The input PDF is encrypted. OCRmyPDF does not read encrypted PDFs. Use another program such as ``qpdf`` to remove encryption.
+    *	- 9
+        - ``ExitCode.invalid_config``
+        - A custom configuration file was forwarded to Tesseract using ``--tesseract-config``, and Tesseract rejected this file.
+    *   - 10
+        - ``ExitCode.pdfa_conversion_failed``
+        - A valid PDF was created, PDF/A conversion failed. The file will be available.
+    *	- 15
+        - ``ExitCode.other_error``
+        - Some other error occurred.
+    *	- 130
+        - ``ExitCode.ctrl_c``
+        - The program was interrupted by pressing Ctrl+C.
+
+
+Debugging the intermediate files
+================================
+
+OCRmyPDF normally saves its intermediate results to a temporary folder
+and deletes this folder when it exits, whether it succeeded or failed.
+
+If the ``-k`` argument is issued on the command line, OCRmyPDF will keep
+the temporary folder and print the location, whether it succeeded or
+failed (provided the Python interpreter did not crash). An example
+message is:
+
+.. code-block:: none
+
+    Temporary working files retained at:
+    /tmp/ocrmypdf.io.u20wpz07
+
+The organization of this folder is an implementation detail and subject
+to change between releases. However the general organization is that
+working files on a per page basis have the page number as a prefix
+(starting with page 1), an infix indicates the processing stage, and a
+suffix indicates the file type. Some important files include:
+
+-  ``_rasterize.png`` - what the input page looks like
+-  ``_ocr.png`` - the file that is sent to Tesseract for OCR; depending
+   on arguments this may differ from the presentation image
+-  ``_pp_deskew.png`` - the image, after deskewing
+-  ``_pp_clean.png`` - the image, after cleaning with unpaper
+-  ``_ocr_tess.pdf`` - the OCR file; appears as a blank page with invisible
+   text embedded
+-  ``_ocr_tess.txt`` - the OCR text (not necessarily all text on the page,
+   if the page is mixed format)
+-  ``fix_docinfo.pdf`` - a temporary file created to fix the PDF DocumentInfo
+   data structure
+-  ``graft_layers.pdf`` - the rendered PDF with OCR layers grafted on
+-  ``pdfa.pdf`` - ``graft_layers.pdf`` after conversion to PDF/A
+-  ``pdfa.ps`` - a PostScript file used by Ghostscript for PDF/A conversion
+-  ``optimize.pdf`` - the PDF generated before optimization
+-  ``optimize.out.pdf`` - the PDF generated by optimization
+-  ``origin`` - the input file
+-  ``origin.pdf`` - the input file or the input image converted to PDF
+-  ``images/*`` - images extracted during the optimization process; here
+   the prefix indicates a PDF object ID not a page number

docs/api.rst

@@ -0,0 +1,117 @@
+======================
+Using the OCRmyPDF API
+======================
+
+OCRmyPDF originated as a command line program and continues to have this
+legacy, but parts of it can be imported and used in other Python
+applications.
+
+Some applications may want to consider running ocrmypdf from a
+subprocess call anyway, as this provides isolation of its activities.
+
+Example
+=======
+
+OCRmyPDF provides one high-level function to run its main engine from an
+application. The parameters are symmetric to the command line arguments
+and largely have the same functions.
+
+.. code-block:: python
+
+    import ocrmypdf
+
+    if __name__ == '__main__':  # To ensure correct behavior on Windows and macOS
+        ocrmypdf.ocr('input.pdf', 'output.pdf', deskew=True)
+
+With some exceptions, all of the command line arguments are available
+and may be passed as equivalent keywords.
+
+A few differences are that ``verbose`` and ``quiet`` are not available.
+Instead, output should be managed by configuring logging.
+
+Parent process requirements
+---------------------------
+
+The :func:`ocrmypdf.ocr` function runs OCRmyPDF similar to command line
+execution. To do this, it will:
+
+- create a monitoring thread
+- create worker processes (on Linux, forking itself; on Windows and macOS, by
+  spawning)
+- manage the signal flags of its worker processes
+- execute other subprocesses (forking and executing other programs)
+
+The Python process that calls :func:`ocrmypdf.ocr()` must be sufficiently
+privileged to perform these actions.
+
+There currently is no option to manage how jobs are scheduled other
+than the argument ``jobs=`` which will limit the number of worker
+processes.
+
+Creating a child process to call :func:`ocrmypdf.ocr()` is suggested. That
+way your application will survive and remain interactive even if
+OCRmyPDF fails for any reason.
+
+Programs that call :func:`ocrmypdf.ocr()` should also install a SIGBUS signal
+handler (except on Windows), to raise an exception if access to a memory
+mapped file fails. OCRmyPDF may use memory mapping.
+
+:func:`ocrmypdf.ocr()` will take a threading lock to prevent multiple runs of itself
+in the same Python interpreter process. This is not thread-safe, because of how
+OCRmyPDF's plugins and Python's library import system work. If you need to parallelize
+OCRmyPDF, use processes.
+
+.. warning::
+
+    On Windows and macOS, the script that calls :func:`ocrmypdf.ocr()` must be
+    protected by an "ifmain" guard (``if __name__ == '__main__'``). If you do
+    not take at least one of these steps, process semantics will prevent
+    OCRmyPDF from working correctly.
+
+Logging
+-------
+
+OCRmyPDF will log under loggers named ``ocrmypdf``. In addition, it
+imports ``pdfminer`` and ``PIL``, both of which post log messages under
+those logging namespaces.
+
+You can configure the logging as desired for your application or call
+:func:`ocrmypdf.configure_logging` to configure logging the same way
+OCRmyPDF itself does. The command line parameters such as ``--quiet``
+and ``--verbose`` have no equivalents in the API; you must use the
+provided configuration function or do configuration in a way that suits
+your use case.
+
+Progress monitoring
+-------------------
+
+OCRmyPDF uses the ``tqdm`` package to implement its progress bars.
+:func:`ocrmypdf.configure_logging` will set up logging output to
+``sys.stderr`` in a way that is compatible with the display of the
+progress bar. Use ``ocrmypdf.ocr(...progress_bar=False)`` to disable
+the progress bar.
+
+Exceptions
+----------
+
+OCRmyPDF may throw standard Python exceptions, ``ocrmypdf.exceptions.*``
+exceptions, some exceptions related to multiprocessing, and
+:exc:`KeyboardInterrupt`. The parent process should provide an exception
+handler. OCRmyPDF will clean up its temporary files and worker processes
+automatically when an exception occurs.
+
+Programs that call OCRmyPDF should consider trapping KeyboardInterrupt
+so that they allow OCR to terminate with the whole program terminating.
+
+When OCRmyPDF succeeds conditionally, it returns an integer exit code.
+
+Reference
+---------
+
+.. autofunction:: ocrmypdf.ocr
+
+.. autoclass:: ocrmypdf.Verbosity
+    :members:
+    :undoc-members:
+
+.. autofunction:: ocrmypdf.configure_logging

docs/apiref.rst

@@ -0,0 +1,55 @@
+=============
+API Reference
+=============
+
+This page summarizes the rest of the public API. Generally speaking this
+should mainly of interest to plugin developers.
+
+ocrmypdf
+========
+
+.. autoclass:: ocrmypdf.PageContext
+    :members:
+
+.. autoclass:: ocrmypdf.PdfContext
+    :members:
+
+ocrmypdf.exceptions
+===================
+
+.. automodule:: ocrmypdf.exceptions
+    :members:
+    :undoc-members:
+
+ocrmypdf.helpers
+================
+
+.. automodule:: ocrmypdf.helpers
+    :members:
+    :noindex: deprecated
+
+    .. autodecorator:: deprecated
+
+ocrmypdf.hocrtransform
+======================
+
+.. automodule:: ocrmypdf.hocrtransform
+    :members:
+
+ocrmypdf.pdfa
+=============
+
+.. automodule:: ocrmypdf.pdfa
+    :members:
+
+ocrmypdf.quality
+================
+
+.. automodule:: ocrmypdf.quality
+    :members:
+
+ocrmypdf.subprocess
+===================
+
+.. automodule:: ocrmypdf.subprocess
+    :members:

docs/batch.rst

@@ -0,0 +1,217 @@
+================
+Batch processing
+================
+
+This article provides information about running OCRmyPDF on multiple
+files or configuring it as a service triggered by file system events.
+
+Batch jobs
+==========
+
+Consider using the excellent `GNU
+Parallel <https://www.gnu.org/software/parallel/>`__ to apply OCRmyPDF
+to multiple files at once.
+
+Both ``parallel`` and ``ocrmypdf`` will try to use all available
+processors. To maximize parallelism without overloading your system with
+processes, consider using ``parallel -j 2`` to limit parallel to running
+two jobs at once.
+
+This command will run all ocrmypdf all files named ``*.pdf`` in the
+current directory and write them to the previous created ``output/``
+folder. It will not search subdirectories.
+
+The ``--tag`` argument tells parallel to print the filename as a prefix
+whenever a message is printed, so that one can trace any errors to the
+file that produced them.
+
+.. code-block:: bash
+
+   parallel --tag -j 2 ocrmypdf '{}' 'output/{}' ::: *.pdf
+
+OCRmyPDF automatically repairs PDFs before parsing and gathering
+information from them.
+
+Directory trees
+===============
+
+This will walk through a directory tree and run OCR on all files in
+place, printing the output in a way that makes
+
+.. code-block:: bash
+
+   find . -printf '%p' -name '*.pdf' -exec ocrmypdf '{}' '{}' \;
+
+Alternatively, with a docker container (mounts a volume to the container
+where the PDFs are stored):
+
+.. code-block:: bash
+
+   find . -printf '%p' -name '*.pdf' -exec docker run --rm -v <host dir>:<container dir> jbarlow83/ocrmypdf '<container dir>/{}' '<container dir>/{}' \;
+
+This only runs one ``ocrmypdf`` process at a time. This variation uses
+``find`` to create a directory list and ``parallel`` to parallelize runs
+of ``ocrmypdf``, again updating files in place.
+
+.. code-block:: bash
+
+   find . -name '*.pdf' | parallel --tag -j 2 ocrmypdf '{}' '{}'
+
+In a Windows batch file, use
+
+.. code-block:: bat
+
+   for /r %%f in (*.pdf) do ocrmypdf %%f %%f
+
+Sample script
+-------------
+
+This user contributed script also provides an example of batch
+processing.
+
+.. literalinclude:: ../misc/batch.py
+    :caption: misc/batch.py
+
+Synology DiskStations
+---------------------
+
+Synology DiskStations (Network Attached Storage devices) can run the
+Docker image of OCRmyPDF if the Synology `Docker
+package <https://www.synology.com/en-global/dsm/packages/Docker>`__ is
+installed. Attached is a script to address particular quirks of using
+OCRmyPDF on one of these devices.
+
+This is only possible for x86-based Synology products. Some Synology
+products use ARM or Power processors and do not support Docker. Further
+adjustments might be needed to deal with the Synology's relatively
+limited CPU and RAM.
+
+.. literalinclude:: ../misc/synology.py
+    :caption: misc/synology.py - Sample script for Synology DiskStations
+
+Huge batch jobs
+---------------
+
+If you have thousands of files to work with, contact the author.
+Consulting work related to OCRmyPDF helps fund this open source project
+and all inquiries are appreciated.
+
+Hot (watched) folders
+=====================
+
+Watched folders with watcher.py
+-------------------------------
+
+OCRmyPDF has a folder watcher called watcher.py, which is currently included in source
+distributions but not part of the main program. It may be used natively or may run
+in a Docker container. Native instances tend to give better performance. watcher.py
+works on all platforms.
+
+Users may need to customize the script to meet their requirements.
+
+.. code-block:: bash
+
+    pip3 install ocrmypdf[watcher]
+
+    env OCR_INPUT_DIRECTORY=/mnt/input-pdfs \
+        OCR_OUTPUT_DIRECTORY=/mnt/output-pdfs \
+        OCR_OUTPUT_DIRECTORY_YEAR_MONTH=1 \
+        python3 watcher.py
+
+.. csv-table:: watcher.py environment variables
+    :header: "Environment variable", "Description"
+    :widths: 50, 50
+
+    "OCR_INPUT_DIRECTORY", "Set input directory to monitor (recursive)"
+    "OCR_OUTPUT_DIRECTORY", "Set output directory (should not be under input)"
+    "OCR_ON_SUCCESS_DELETE", "This will delete the input file if the exit code is 0 (OK)"
+    "OCR_OUTPUT_DIRECTORY_YEAR_MONTH", "This will place files in the output in ``{output}/{year}/{month}/{filename}``"
+    "OCR_DESKEW", "Apply deskew to crooked input PDFs"
+    "OCR_JSON_SETTINGS", "A JSON string specifying any other arguments for ``ocrmypdf.ocr``, e.g. ``'OCR_JSON_SETTINGS={""rotate_pages"": true}'``."
+    "OCR_POLL_NEW_FILE_SECONDS", "Polling interval"
+    "OCR_LOGLEVEL", "Level of log messages to report"
+
+One could configure a networked scanner or scanning computer to drop files in the
+watched folder.
+
+Watched folders with Docker
+---------------------------
+
+The watcher service is included in the OCRmyPDF Docker image. To run it:
+
+.. code-block:: bash
+
+    docker run \
+        -v <path to files to convert>:/input \
+        -v <path to store results>:/output \
+        -e OCR_OUTPUT_DIRECTORY_YEAR_MONTH=1 \
+        -e OCR_ON_SUCCESS_DELETE=1 \
+        -e OCR_DESKEW=1 \
+        -e PYTHONUNBUFFERED=1 \
+        -it --entrypoint python3 \
+        jbarlow83/ocrmypdf \
+        watcher.py
+
+This service will watch for a file that matches ``/input/\*.pdf`` and will
+convert it to a OCRed PDF in ``/output/``. The parameters to this image are:
+
+.. csv-table:: watcher.py parameters for Docker
+    :header: "Parameter", "Description"
+    :widths: 50, 50
+
+    "``-v <path to files to convert>:/input``", "Files placed in this location will be OCRed"
+    "``-v <path to store results>:/output``", "This is where OCRed files will be stored"
+    "``-e OCR_OUTPUT_DIRECTORY_YEAR_MONTH=1``", "Define environment variable OCR_OUTPUT_DIRECTORY_YEAR_MONTH=1"
+    "``-e OCR_ON_SUCCESS_DELETE=1``", "Define environment variable"
+    "``-e OCR_DESKEW=1``", "Define environment variable"
+    "``-e PYTHONBUFFERED=1``", "This will force STDOUT to be unbuffered and allow you to see messages in docker logs"
+
+This service relies on polling to check for changes to the filesystem. It
+may not be suitable for some environments, such as filesystems shared on a
+slow network.
+
+A configuration manager such as Docker Compose could be used to ensure that the
+service is always available.
+
+.. literalinclude:: ../misc/docker-compose.example.yml
+    :language: yaml
+    :caption: misc/docker-compose.example.yml
+
+Caveats
+-------
+
+-  ``watchmedo`` may not work properly on a networked file system,
+   depending on the capabilities of the file system client and server.
+-  This simple recipe does not filter for the type of file system event,
+   so file copies, deletes and moves, and directory operations, will all
+   be sent to ocrmypdf, producing errors in several cases. Disable your
+   watched folder if you are doing anything other than copying files to
+   it.
+-  If the source and destination directory are the same, watchmedo may
+   create an infinite loop.
+-  On BSD, FreeBSD and older versions of macOS, you may need to increase
+   the number of file descriptors to monitor more files, using
+   ``ulimit -n 1024`` to watch a folder of up to 1024 files.
+
+Alternatives
+------------
+
+-  On Linux, `systemd user services <https://wiki.archlinux.org/index.php/Systemd/User>`__
+   can be configured to automatically perform OCR on a collection of files.
+
+-  `Watchman <https://facebook.github.io/watchman/>`__ is a more
+   powerful alternative to ``watchmedo``.
+
+macOS Automator
+===============
+
+You can use the Automator app with macOS, to create a Workflow or Quick
+Action. Use a *Run Shell Script* action in your workflow. In the context
+of Automator, the ``PATH`` may be set differently your Terminal's
+``PATH``; you may need to explicitly set the PATH to include
+``ocrmypdf``. The following example may serve as a starting point:
+
+.. figure:: images/macos-workflow.png
+    :alt: Example macOS Automator workflow
+
+You may customize the command sent to ocrmypdf.

docs/conf.py

@@ -0,0 +1,383 @@
+#!/usr/bin/env python3
+#
+# ocrmypdf documentation build configuration file, created by
+# sphinx-quickstart on Sun Sep  4 14:29:43 2016.
+#
+# This file is execfile()d with the current directory set to its
+# containing dir.
+#
+# Note that not all possible configuration values are present in this
+# autogenerated file.
+#
+# All configuration values have a default; values that are commented out
+# serve to show the default.
+
+# If extensions (or modules to document with autodoc) are in another directory,
+# add these directories to sys.path here. If the directory is relative to the
+# documentation root, use os.path.abspath to make it absolute, like shown here.
+#
+# import os
+# import sys
+# sys.path.insert(0, os.path.abspath('.'))
+
+"""isort:skip_file"""
+
+# -- General configuration ------------------------------------------------
+
+# If your documentation needs a minimal Sphinx version, state it here.
+#
+# needs_sphinx = '1.0'
+
+# Add any Sphinx extension module names here, as strings. They can be
+# extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
+# ones.
+extensions = [
+    'sphinx.ext.autodoc',
+    'sphinx.ext.intersphinx',
+    'sphinx.ext.autosummary',
+    'sphinx.ext.napoleon',
+    'sphinx_issues',
+]
+
+# Extension settings
+intersphinx_mapping = {'https://docs.python.org/': None}
+napoleon_use_rtype = False
+issues_github_path = "jbarlow83/OCRmyPDF"
+
+# Add any paths that contain templates here, relative to this directory.
+templates_path = ['_templates']
+
+# The suffix(es) of source filenames.
+# You can specify multiple suffix as a list of string:
+#
+# source_suffix = ['.rst', '.md']
+source_suffix = '.rst'
+
+# The encoding of source files.
+#
+# source_encoding = 'utf-8-sig'
+
+# The master toctree document.
+master_doc = 'index'
+
+# General information about the project.
+project = 'ocrmypdf'
+copyright = (
+    '2021, James R. Barlow. Licensed under Creative Commons Attribution-ShareAlike 4.0.'
+)
+author = 'James R. Barlow'
+
+# The version info for the project you're documenting, acts as replacement for
+# |version| and |release|, also used in various other places throughout the
+# built documents.
+#
+# The short X.Y version.
+
+import os
+
+on_rtd = os.environ.get('READTHEDOCS') == 'True'
+
+if on_rtd:
+    # Help ReadTheDocs avoid having to install any binary extension modules
+    import sys
+    from unittest.mock import MagicMock
+
+    class Mock(MagicMock):
+        @classmethod
+        def __getattr__(cls, name):
+            return MagicMock()
+
+    MOCK_MODULES = [
+        'pikepdf',
+        'pikepdf.models',
+        'pikepdf.models.metadata',
+    ]
+    sys.modules.update((mod_name, Mock()) for mod_name in MOCK_MODULES)
+
+try:
+    from importlib_metadata import version as package_version
+except ModuleNotFoundError:
+    from importlib.metadata import version as package_version
+
+# The full version, including alpha/beta/rc tags.
+release = package_version('ocrmypdf')
+version = '.'.join(release.split('.')[:2])
+
+
+# The language for content autogenerated by Sphinx. Refer to documentation
+# for a list of supported languages.
+#
+# This is also used if you do content translation via gettext catalogs.
+# Usually you set "language" from the command line for these cases.
+language = None
+
+# There are two options for replacing |today|: either, you set today to some
+# non-false value, then it is used:
+#
+# today = ''
+#
+# Else, today_fmt is used as the format for a strftime call.
+#
+today_fmt = '%Y-%m-%d'
+
+# List of patterns, relative to source directory, that match files and
+# directories to ignore when looking for source files.
+# This patterns also effect to html_static_path and html_extra_path
+exclude_patterns = ['_build', 'Thumbs.db', '.DS_Store']
+
+# The reST default role (used for this markup: `text`) to use for all
+# documents.
+#
+# default_role = None
+
+# If true, '()' will be appended to :func: etc. cross-reference text.
+#
+# add_function_parentheses = True
+
+# If true, the current module name will be prepended to all description
+# unit titles (such as .. function::).
+#
+# add_module_names = True
+
+# If true, sectionauthor and moduleauthor directives will be shown in the
+# output. They are ignored by default.
+#
+# show_authors = False
+
+# The name of the Pygments (syntax highlighting) style to use.
+pygments_style = 'sphinx'
+
+# A list of ignored prefixes for module index sorting.
+# modindex_common_prefix = []
+
+# If true, keep warnings as "system message" paragraphs in the built documents.
+# keep_warnings = False
+
+# If true, `todo` and `todoList` produce output, else they produce nothing.
+todo_include_todos = False
+
+
+# -- Options for HTML output ----------------------------------------------
+
+import sphinx_rtd_theme
+
+# The theme to use for HTML and HTML Help pages.  See the documentation for
+# a list of builtin themes.
+#
+html_theme = 'sphinx_rtd_theme'
+html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
+
+# Theme options are theme-specific and customize the look and feel of a theme
+# further.  For a list of options available for each theme, see the
+# documentation.
+#
+html_theme_options = {'display_version': False}
+
+# Add any paths that contain custom themes here, relative to this directory.
+# html_theme_path = []
+
+# The name for this set of Sphinx documents.
+# "<project> v<release> documentation" by default.
+#
+# html_title = 'ocrmypdf v4.2'
+
+# A shorter title for the navigation bar.  Default is the same as html_title.
+#
+# html_short_title = None
+
+# The name of an image file (relative to this directory) to place at the top
+# of the sidebar.
+#
+# html_logo = "images/logo.svg"  # looks bad
+
+# The name of an image file (relative to this directory) to use as a favicon of
+# the docs.  This file should be a Windows icon file (.ico) being 16x16 or 32x32
+# pixels large.
+#
+# html_favicon = None
+
+# Add any paths that contain custom static files (such as style sheets) here,
+# relative to this directory. They are copied after the builtin static files,
+# so a file named "default.css" will overwrite the builtin "default.css".
+html_static_path = ['_static']
+
+# Add any extra paths that contain custom files (such as robots.txt or
+# .htaccess) here, relative to this directory. These files are copied
+# directly to the root of the documentation.
+#
+# html_extra_path = []
+
+# If not None, a 'Last updated on:' timestamp is inserted at every page
+# bottom, using the given strftime format.
+# The empty string is equivalent to '%b %d, %Y'.
+#
+# html_last_updated_fmt = None
+
+# If true, SmartyPants will be used to convert quotes and dashes to
+# typographically correct entities.
+#
+# html_use_smartypants = True
+
+# Custom sidebar templates, maps document names to template names.
+#
+# html_sidebars = {}
+
+# Additional templates that should be rendered to pages, maps page names to
+# template names.
+#
+# html_additional_pages = {}
+
+# If false, no module index is generated.
+#
+# html_domain_indices = True
+
+# If false, no index is generated.
+#
+# html_use_index = True
+
+# If true, the index is split into individual pages for each letter.
+#
+# html_split_index = False
+
+# If true, links to the reST sources are added to the pages.
+#
+# html_show_sourcelink = True
+
+# If true, "Created using Sphinx" is shown in the HTML footer. Default is True.
+#
+# html_show_sphinx = True
+
+# If true, "(C) Copyright ..." is shown in the HTML footer. Default is True.
+#
+# html_show_copyright = True
+
+# If true, an OpenSearch description file will be output, and all pages will
+# contain a <link> tag referring to it.  The value of this option must be the
+# base URL from which the finished HTML is served.
+#
+# html_use_opensearch = ''
+
+# This is the file name suffix for HTML files (e.g. ".xhtml").
+# html_file_suffix = None
+
+# Language to be used for generating the HTML full-text search index.
+# Sphinx supports the following languages:
+#   'da', 'de', 'en', 'es', 'fi', 'fr', 'h', 'it', 'ja'
+#   'nl', 'no', 'pt', 'ro', 'r', 'sv', 'tr', 'zh'
+#
+# html_search_language = 'en'
+
+# A dictionary with options for the search language support, empty by default.
+# 'ja' uses this config value.
+# 'zh' user can custom change `jieba` dictionary path.
+#
+# html_search_options = {'type': 'default'}
+
+# The name of a javascript file (relative to the configuration directory) that
+# implements a search results scorer. If empty, the default will be used.
+#
+# html_search_scorer = 'scorer.js'
+
+# Output file base name for HTML help builder.
+htmlhelp_basename = 'ocrmypdfdoc'
+
+# -- Options for LaTeX output ---------------------------------------------
+
+latex_elements = {  # type: ignore
+    # The paper size ('letterpaper' or 'a4paper').
+    #
+    # 'papersize': 'letterpaper',
+    # The font size ('10pt', '11pt' or '12pt').
+    #
+    # 'pointsize': '10pt',
+    # Additional stuff for the LaTeX preamble.
+    #
+    # 'preamble': '',
+    # Latex figure (float) alignment
+    #
+    # 'figure_align': 'htbp',
+}
+
+# Grouping the document tree into LaTeX files. List of tuples
+# (source start file, target name, title,
+#  author, documentclass [howto, manual, or own class]).
+latex_documents = [
+    (master_doc, 'ocrmypdf.tex', 'ocrmypdf Documentation', 'James R. Barlow', 'manual')
+]
+
+# The name of an image file (relative to this directory) to place at the top of
+# the title page.
+#
+# latex_logo = None
+
+# For "manual" documents, if this is true, then toplevel headings are parts,
+# not chapters.
+#
+# latex_use_parts = False
+
+# If true, show page references after internal links.
+#
+# latex_show_pagerefs = False
+
+# If true, show URL addresses after external links.
+#
+# latex_show_urls = False
+
+# Documents to append as an appendix to all manuals.
+#
+# latex_appendices = []
+
+# It false, will not define \strong, \code, 	itleref, \crossref ... but only
+# \sphinxstrong, ..., \sphinxtitleref, ... To help avoid clash with user added
+# packages.
+#
+# latex_keep_old_macro_names = True
+
+# If false, no module index is generated.
+#
+# latex_domain_indices = True
+
+
+# -- Options for manual page output ---------------------------------------
+
+# One entry per manual page. List of tuples
+# (source start file, name, description, authors, manual section).
+man_pages = [(master_doc, 'ocrmypdf', 'ocrmypdf Documentation', [author], 1)]
+
+# If true, show URL addresses after external links.
+#
+# man_show_urls = False
+
+
+# -- Options for Texinfo output -------------------------------------------
+
+# Grouping the document tree into Texinfo files. List of tuples
+# (source start file, target name, title, author,
+#  dir menu entry, description, category)
+texinfo_documents = [
+    (
+        master_doc,
+        'ocrmypdf',
+        'ocrmypdf Documentation',
+        author,
+        'ocrmypdf',
+        'One line description of project.',
+        'Miscellaneous',
+    )
+]
+
+# Documents to append as an appendix to all manuals.
+#
+# texinfo_appendices = []
+
+# If false, no module index is generated.
+#
+# texinfo_domain_indices = True
+
+# How to display URL addresses: 'footnote', 'no', or 'inline'.
+#
+# texinfo_show_urls = 'footnote'
+
+# If true, do not generate a @detailmenu in the "Top" node's menu.
+#
+# texinfo_no_detailmenu = False

docs/contributing.rst

@@ -0,0 +1,67 @@
+=======================
+Contributing guidelines
+=======================
+
+Contributions are welcome!
+
+Big changes
+===========
+
+Please open a new issue to discuss or propose a major change. Not only is it fun
+to discuss big ideas, but we might save each other's time too. Perhaps some of the
+work you're contemplating is already half-done in a development branch.
+
+Code style
+==========
+
+We use PEP8, ``black`` for code formatting and ``isort`` for import sorting. The
+settings for these programs are in ``pyproject.toml`` and ``setup.cfg``. Pull
+requests should follow the style guide. One difference we use from "black" style
+is that strings shown to the user are always in double quotes (``"``) and strings
+for internal uses are in single quotes (``'``).
+
+Tests
+=====
+
+New features should come with tests that confirm their correctness.
+
+New Python dependencies
+=======================
+
+If you are proposing a change that will require a new Python dependency, we
+prefer dependencies that are already packaged by Debian or Red Hat. This makes
+life much easier for our downstream package maintainers.
+
+Python dependencies must also be license-compatible. GPLv3 or AGPLv3 are likely
+incompatible with the project's license, but LGPLv3 is compatible.
+
+New non-Python dependencies
+===========================
+
+OCRmyPDF uses several external programs (Tesseract, Ghostscript and others) for
+its functionality. In general we prefer to avoid adding new external programs.
+
+Style guide: Is it OCRmyPDF or ocrmypdf?
+========================================
+
+The program/project is OCRmyPDF and the name of the executable or library is ocrmypdf.
+
+Known ports/packagers
+=====================
+
+OCRmyPDF has been ported to many platforms already. If you are interesting in
+porting to a new platform, check with
+`Repology <https://repology.org/projects/?search=ocrmypdf>`__ to see the status
+of that platform.
+
+Packager maintainers, please ensure that the command line completion scripts in
+``misc/`` are installed.
+
+Copyright and license
+=====================
+
+For contributions over 10 lines of code, please include your name to list of
+copyright holders for that file. The core program is licensed under MPL-2.0,
+test files and documentation under CC-BY-SA 4.0, and miscellaneous files under
+MIT. Please contribute code only that you wrote and you have the permission to
+contribute or license to us.

docs/cookbook.rst

@@ -0,0 +1,358 @@
+========
+Cookbook
+========
+
+Basic examples
+==============
+
+Help!
+-----
+
+ocrmypdf has built-in help.
+
+.. code-block:: bash
+
+    ocrmypdf --help
+
+Add an OCR layer and convert to PDF/A
+-------------------------------------
+
+.. code-block:: bash
+
+    ocrmypdf input.pdf output.pdf
+
+Add an OCR layer and output a standard PDF
+------------------------------------------
+
+.. code-block:: bash
+
+    ocrmypdf --output-type pdf input.pdf output.pdf
+
+Create a PDF/A with all color and grayscale images converted to JPEG
+--------------------------------------------------------------------
+
+.. code-block:: bash
+
+    ocrmypdf --output-type pdfa --pdfa-image-compression jpeg input.pdf output.pdf
+
+Modify a file in place
+----------------------
+
+The file will only be overwritten if OCRmyPDF is successful.
+
+.. code-block:: bash
+
+    ocrmypdf myfile.pdf myfile.pdf
+
+Correct page rotation
+---------------------
+
+OCR will attempt to automatic correct the rotation of each page. This
+can help fix a scanning job that contains a mix of landscape and
+portrait pages.
+
+.. code-block:: bash
+
+    ocrmypdf --rotate-pages myfile.pdf myfile.pdf
+
+You can increase (decrease) the parameter ``--rotate-pages-threshold``
+to make page rotation more (less) aggressive. The threshold number is the ratio
+of how confidence the OCR engine is that the document image should be changed,
+compared to kept the same. The default value is quite conservative; on some files
+it may not attempt rotations at all unless it is very confident that the current
+rotation is wrong. A lower value of ``2.0`` will produce more rotations, and
+more false positives. Run with ``-v1`` to see the confidence level for each
+page to see if there may be a better value for your files.
+
+If the page is "just a little off horizontal", like a crooked picture,
+then you want ``--deskew``. ``--rotate-pages`` is for when the cardinal
+angle is wrong.
+
+OCR languages other than English
+--------------------------------
+
+OCRmyPDF assumes the document is in English unless told otherwise. OCR
+quality may be poor if the wrong language is used.
+
+.. code-block:: bash
+
+    ocrmypdf -l fra LeParisien.pdf LeParisien.pdf
+    ocrmypdf -l eng+fra Bilingual-English-French.pdf Bilingual-English-French.pdf
+
+Language packs must be installed for all languages specified. See
+:ref:`Installing additional language packs <lang-packs>`.
+
+Unfortunately, the Tesseract OCR engine has no ability to detect the
+language when it is unknown.
+
+Produce PDF and text file containing OCR text
+---------------------------------------------
+
+This produces a file named "output.pdf" and a companion text file named
+"output.txt".
+
+.. code-block:: bash
+
+    ocrmypdf --sidecar output.txt input.pdf output.pdf
+
+.. note::
+
+    The sidecar file contains the **OCR text** found by OCRmyPDF. If the document
+    contains pages that already have text, that text will not appear in the
+    sidecar. If the option ``--pages`` is used, only those pages on which OCR
+    was performed will be included in the sidecar. If certain pages were skipped
+    because of options like ``--skip-big`` or ``--tesseract-timeout``, those pages
+    will not be in the sidecar.
+
+    To extract all text from a PDF, whether generated from OCR or otherwise,
+    use a program like Poppler's ``pdftotext`` or ``pdfgrep``.
+
+OCR images, not PDFs
+--------------------
+
+Option: use Tesseract
+~~~~~~~~~~~~~~~~~~~~~
+
+If you are starting with images, you can just use Tesseract directly to
+convert images to PDFs:
+
+.. code-block:: bash
+
+    tesseract my-image.jpg output-prefix pdf
+
+.. code-block:: bash
+
+    # When there are multiple images
+    tesseract text-file-containing-list-of-image-filenames.txt output-prefix pdf
+
+Tesseract's PDF output is quite good – OCRmyPDF uses it internally, in
+some cases. However, OCRmyPDF has many features not available in
+Tesseract like image processing, metadata control, and PDF/A generation.
+
+Option: use img2pdf
+~~~~~~~~~~~~~~~~~~~
+
+You can also use a program like
+`img2pdf <https://gitlab.mister-muffin.de/josch/img2pdf>`__ to convert
+your images to PDFs, and then pipe the results to run ocrmypdf. The
+``-`` tells ocrmypdf to read standard input.
+
+.. code-block:: bash
+
+    img2pdf my-images*.jpg | ocrmypdf - myfile.pdf
+
+``img2pdf`` is recommended because it does an excellent job at
+generating PDFs without transcoding images.
+
+Option: use OCRmyPDF (single images only)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+For convenience, OCRmyPDF can also convert single images to PDFs on its
+own. If the resolution (dots per inch, DPI) of an image is not set or is
+incorrect, it can be overridden with ``--image-dpi``. (As 1 inch is 2.54
+cm, 1 dpi = 0.39 dpcm).
+
+.. code-block:: bash
+
+    ocrmypdf --image-dpi 300 image.png myfile.pdf
+
+If you have multiple images, you must use ``img2pdf`` to convert the
+images to PDF.
+
+Not recommended
+~~~~~~~~~~~~~~~
+
+We caution against using ImageMagick or Ghostscript to convert images to
+PDF, since they may transcode images or produce downsampled images,
+sometimes without warning.
+
+Image processing
+================
+
+OCRmyPDF perform some image processing on each page of a PDF, if
+desired. The same processing is applied to each page. It is suggested
+that the user review files after image processing as these commands
+might remove desirable content, especially from poor quality scans.
+
+-  ``--rotate-pages`` attempts to determine the correct orientation for
+   each page and rotates the page if necessary.
+-  ``--remove-background`` attempts to detect and remove a noisy
+   background from grayscale or color images. Monochrome images are
+   ignored. This should not be used on documents that contain color
+   photos as it may remove them.
+-  ``--deskew`` will correct pages were scanned at a skewed angle by
+   rotating them back into place.
+-  ``--clean`` uses
+   `unpaper <https://www.flameeyes.eu/projects/unpaper>`__ to clean up
+   pages before OCR, but does not alter the final output. This makes it
+   less likely that OCR will try to find text in background noise.
+-  ``--clean-final`` uses unpaper to clean up pages before OCR and
+   inserts the page into the final output. You will want to review each
+   page to ensure that unpaper did not remove something important.
+
+.. note::
+
+   In many cases image processing will rasterize PDF pages as images,
+   potentially losing quality.
+
+.. warning::
+
+   ``--clean-final`` and ``-remove-background`` may leave undesirable
+   visual artifacts in some images where their algorithms have
+   shortcomings. Files should be visually reviewed after using these
+   options.
+
+Example: OCR and correct document skew (crooked scan)
+-----------------------------------------------------
+
+Deskew:
+
+.. code-block:: bash
+
+    ocrmypdf --deskew input.pdf output.pdf
+
+Image processing commands can be combined. The order in which options
+are given does not matter. OCRmyPDF always applies the steps of the
+image processing pipeline in the same order (rotate, remove background,
+deskew, clean).
+
+.. code-block:: bash
+
+    ocrmypdf --deskew --clean --rotate-pages input.pdf output.pdf
+
+Don't actually OCR my PDF
+=========================
+
+If you set ``--tesseract-timeout 0`` OCRmyPDF will apply its image
+processing without performing OCR, if all you want to is to apply image
+processing or PDF/A conversion.
+
+.. code-block:: bash
+
+    ocrmypdf --tesseract-timeout=0 --remove-background input.pdf output.pdf
+
+Optimize images without performing OCR
+--------------------------------------
+
+You can also optimize all images without performing any OCR:
+
+.. code-block:: bash
+
+    ocrmypdf --tesseract-timeout=0 --optimize 3 --skip-text input.pdf output.pdf
+
+Perform OCR only certain pages
+------------------------------
+
+You can ask OCRmyPDF to only apply OCR to certain pages.
+
+.. code-block:: bash
+
+    ocrmypdf --pages 2,3,13-17 input.pdf output.pdf
+
+Hyphens denote a range of pages and commas separate page numbers. If you prefer
+to use spaces, quote all of the page numbers: ``--pages '2, 3, 5, 7'``.
+
+OCRmyPDF will warn if your list of page numbers contains duplicates or
+overlap pages. OCRmyPDF does not currently account for document page numbers,
+such as an introduction section of a book that uses Roman numerals. It simply
+counts the number of virtual pieces of paper since the start.
+
+Regardless of the argument to ``--pages``, OCRmyPDF will optimize all pages in
+the file and convert it to PDF/A, unless you disable those options. In this
+example, we want to OCR only the title and otherwise change the PDF as little
+as possible:
+
+.. code-block:: bash
+
+    ocrmypdf --pages 1 --output-type pdf --optimize 0 input.pdf output.pdf
+
+Redo existing OCR
+=================
+
+To redo OCR on a file OCRed with other OCR software or a previous
+version of OCRmyPDF and/or Tesseract, you may use the ``--redo-ocr``
+argument. (Normally, OCRmyPDF will exit with an error if asked to modify
+a file with OCR.)
+
+This may be helpful for users who want to take advantage of accuracy
+improvements in Tesseract 4.0 for files they previously OCRed with an
+earlier version of Tesseract and OCRmyPDF.
+
+.. code-block:: bash
+
+    ocrmypdf --redo-ocr input.pdf output.pdf
+
+This method will replace OCR without rasterizing, reducing quality or
+removing vector content. If a file contains a mix of pure digital text
+and OCR, digital text will be ignored and OCR will be replaced. As such
+this mode is incompatible with image processing options, since they
+alter the appearance of the file.
+
+In some cases, existing OCR cannot be detected or replaced. Files
+produced by OCRmyPDF v2.2 or earlier, for example, are internally
+represented as having visible text with an opaque image drawn on top.
+This situation cannot be detected.
+
+If ``--redo-ocr`` does not work, you can use ``--force-ocr``, which will
+force rasterization of all pages, potentially reducing quality or losing
+vector content.
+
+Improving OCR quality
+=====================
+
+The `Image processing <#image-processing>`__ features can improve OCR
+quality.
+
+Rotating pages and deskewing helps to ensure that the page orientation
+is correct before OCR begins. Removing the background and/or cleaning
+the page can also improve results. The ``--oversample DPI`` argument can
+be specified to resample images to higher resolution before attempting
+OCR; this can improve results as well.
+
+OCR quality will suffer if the resolution of input images is not correct
+(since the range of pixel sizes that will be checked for possible fonts
+will also be incorrect).
+
+PDF optimization
+================
+
+By default OCRmyPDF will attempt to perform lossless optimizations on
+the images inside PDFs after OCR is complete. Optimization is performed
+even if no OCR text is found.
+
+The ``--optimize N`` (short form ``-O``) argument controls optimization,
+where ``N`` ranges from 0 to 3 inclusive, analogous to the optimization
+levels in the GCC compiler.
+
+.. list-table::
+    :widths: auto
+    :header-rows: 1
+
+    *   - Level
+        - Comments
+    *   - ``--optimize 0``
+        - Disables optimization.
+    *   - ``--optimize 1``
+        - Enables lossless optimizations, such as transcoding images to more
+          efficient formats. Also compress other uncompressed objects in the
+          PDF and enables the more efficient "object streams" within the PDF.
+    *   - ``--optimize 2``
+        - All of the above, and enables lossy optimizations and color quantization.
+    *   - ``--optimize 3``
+        - All of the above, and enables more aggressive optimizations and targets lower image quality.
+
+Optimization is improved when a JBIG2 encoder is available and when
+``pngquant`` is installed. If either of these components are missing,
+then some types of images cannot be optimized.
+
+The types of optimization available may expand over time. By default,
+OCRmyPDF compresses data streams inside PDFs, and will change
+inefficient compression modes to more modern versions. A program like
+``qpdf`` can be used to change encodings, e.g. to inspect the internals
+fo a PDF.
+
+.. code-block:: bash
+
+    ocrmypdf --optimize 3 in.pdf out.pdf  # Make it small
+
+Some users may consider enabling lossy JBIG2. See: :ref:`jbig2-lossy`.

docs/docker.rst

@@ -0,0 +1,196 @@
+.. _docker:
+
+=====================
+OCRmyPDF Docker image
+=====================
+
+OCRmyPDF is also available in a Docker image that packages recent
+versions of all dependencies.
+
+For users who already have Docker installed this may be an easy and
+convenient option. However, it is less performant than a system
+installation and may require Docker engine configuration.
+
+OCRmyPDF needs a generous amount of RAM, CPU cores, temporary storage
+space, whether running in a Docker container or on its own. It may be
+necessary to ensure the container is provisioned with additional
+resources.
+
+.. _docker-install:
+
+Installing the Docker image
+===========================
+
+If you have `Docker <https://docs.docker.com/>`__ installed on your
+system, you can install a Docker image of the latest release.
+
+If you can run this command successfully, your system is ready to download and
+execute the image:
+
+.. code-block:: bash
+
+   docker run hello-world
+
+The recommended OCRmyPDF Docker image is currently named ``ocrmypdf``:
+
+.. code-block:: bash
+
+   docker pull jbarlow83/ocrmypdf
+
+
+OCRmyPDF will use all available CPU cores. By default, the VirtualBox
+machine instance on Windows and macOS has only a single CPU core
+enabled. Use the VirtualBox Manager to determine the name of your Docker
+engine host, and then follow these optional steps to enable multiple
+CPUs:
+
+.. code-block:: bash
+
+   # Optional step for Mac OS X users
+   docker-machine stop "yourVM"
+   VBoxManage modifyvm "yourVM" --cpus 2  # or whatever number of core is desired
+   docker-machine start "yourVM"
+   eval $(docker-machine env "yourVM")
+
+See the Docker documentation for
+`adjusting memory and CPU on other platforms <https://docs.docker.com/config/containers/resource_constraints/>`__.
+
+Using the Docker image on the command line
+==========================================
+
+**Unlike typical Docker containers**, in this section the OCRmyPDF Docker
+container is emphemeral – it runs for one OCR job and terminates, just like a
+command line program. We are using Docker to deliver an application (as opposed
+to the more conventional case, where a Docker container runs as a server).
+
+To start a Docker container (instance of the image):
+
+.. code-block:: bash
+
+   docker tag jbarlow83/ocrmypdf ocrmypdf
+   docker run --rm -i ocrmypdf (... all other arguments here...) - -
+
+For convenience, create a shell alias to hide the Docker command. It is
+easier to send the input file as stdin and read the output from
+stdout – **this avoids the messy permission issues with Docker entirely**.
+
+.. code-block:: bash
+
+   alias docker_ocrmypdf='docker run --rm -i ocrmypdf'
+   docker_ocrmypdf --version  # runs docker version
+   docker_ocrmypdf - - <input.pdf >output.pdf
+
+Or in the wonderful `fish shell <https://fishshell.com/>`__:
+
+.. code-block:: fish
+
+   alias docker_ocrmypdf 'docker run --rm ocrmypdf'
+   funcsave docker_ocrmypdf
+
+Alternately, you could mount the local current working directory as a
+Docker volume:
+
+.. code-block:: bash
+
+   alias docker_ocrmypdf='docker run --rm  -i --user "$(id -u):$(id -g)" --workdir /data -v "$PWD:/data" ocrmypdf'
+   docker_ocrmypdf /data/input.pdf /data/output.pdf
+
+.. _docker-lang-packs:
+
+Adding languages to the Docker image
+====================================
+
+By default the Docker image includes English, German, Simplified Chinese,
+French, Portuguese and Spanish, the most popular languages for OCRmyPDF
+users based on feedback. You may add other languages by creating a new
+Dockerfile based on the public one.
+
+.. code-block:: dockerfile
+
+   FROM jbarlow83/ocrmypdf
+
+   # Example: add Italian
+   RUN apt install tesseract-ocr-ita
+
+To install language packs (training data) such as the 
+`tessdata_best <https://github.com/tesseract-ocr/tessdata_best>`_ suite or
+custom data, you first need to determine the version of Tesseract data files, which
+may differ from the Tesseract program version. Use this command to determine the data
+file version:
+
+.. code-block:: bash
+
+   docker run -i --rm --entrypoint /bin/ls jbarlow83/ocrmypdf /usr/share/tesseract-ocr
+
+As of 2021, the data file version is probably ``4.00``.
+
+You can then add new data with either a Dockerfile:
+
+.. code-block:: dockerfile
+
+   FROM jbarlow83/ocrmypdf
+
+   # Example: add a tessdata_best file
+   COPY chi_tra_vert.traineddata /usr/share/tesseract-ocr/<data version>/tessdata/
+
+Alternately, you can copy training data into a Docker container as follows:
+
+.. code-block:: bash
+
+   docker cp mycustomtraining.traineddata name_of_container:/usr/share/tesseract-ocr/<tesseract version>/tessdata/
+
+Executing the test suite
+========================
+
+The OCRmyPDF test suite is installed with image. To run it:
+
+.. code-block:: bash
+
+   docker run --entrypoint python3  jbarlow83/ocrmypdf -m pytest
+
+Accessing the shell
+===================
+
+To use the bash shell in the Docker image:
+
+.. code-block:: bash
+
+   docker run -it --entrypoint bash  jbarlow83/ocrmypdf
+
+Using the OCRmyPDF web service wrapper
+======================================
+
+The OCRmyPDF Docker image includes an example, barebones HTTP web
+service. The webservice may be launched as follows:
+
+.. code-block:: bash
+
+   docker run --entrypoint python3 -p 5000:5000  jbarlow83/ocrmypdf webservice.py
+
+This will configure the machine to listen on port 5000. On Linux machines
+this is port 5000 of localhost. On macOS or Windows machines running
+Docker, this is port 5000 of the virtual machine that runs your Docker
+images. You can find its IP address using the command ``docker-machine ip``.
+
+Unlike command line usage this program will open a socket and wait for
+connections.
+
+.. warning::
+
+   The OCRmyPDF web service wrapper is intended for demonstration or
+   development. It provides no security, no authentication, no
+   protection against denial of service attacks, and no load balancing.
+   The default Flask WSGI server is used, which is intended for
+   development only. The server is single-threaded and so can respond to
+   only one client at a time. While running OCR, it cannot respond to
+   any other clients.
+
+Clients must keep their open connection while waiting for OCR to
+complete. This may entail setting a long timeout; this interface is more
+useful for internal HTTP API calls.
+
+Unlike the rest of OCRmyPDF, this web service is licensed under the
+Affero GPLv3 (AGPLv3) since Ghostscript is also licensed in this way.
+
+In addition to the above, please read our
+:ref:`general remarks on using OCRmyPDF as a service <ocr-service>`.

docs/errors.rst

@@ -0,0 +1,53 @@
+=====================
+Common error messages
+=====================
+
+Page already has text
+=====================
+
+.. code-block::
+
+   ERROR -    1: page already has text! – aborting (use --force-ocr to force OCR)
+
+You ran ocrmypdf on a file that already contains printable text or a
+hidden OCR text layer (it can't quite tell the difference). You probably
+don't want to do this, because the file is already searchable.
+
+As the error message suggests, your options are:
+
+-  ``ocrmypdf --force-ocr`` to :ref:`rasterize <raster-vector>` all
+   vector content and run OCR on the images. This is useful if a
+   previous OCR program failed, or if the document contains a text
+   watermark.
+-  ``ocrmypdf --skip-text`` to skip OCR and other processing on any
+   pages that contain text. Text pages will be copied into the output
+   PDF without modification.
+-  ``ocrmypdf --redo-ocr`` to scan the file for any existing OCR
+   (non-printing text), remove it, and do OCR again. This is one way
+   to take advantage of improvements in OCR accuracy. Printable vector
+   text is excluded from OCR, so this can be used on files that contain
+   a mix of digital and scanned files.
+
+
+Input file 'filename' is not a valid PDF
+========================================
+
+OCRmyPDF checks files with pikepdf, a library that in turn uses libqpdf to fixes
+errors in PDFs, before it tries to work on them. In most cases this happens
+because the PDF is corrupt and truncated (incomplete file copying) and not much
+can be done.
+
+You can try rewriting the file with Ghostscript:
+
+.. code-block:: bash
+
+    gs -o output.pdf -dSAFER -sDEVICE=pdfwrite input.pdf
+
+``pdftk`` can also rewrite PDFs:
+
+.. code-block:: bash
+
+    pdftk input.pdf cat output output.pdf
+
+Sometimes Acrobat can repair PDFs with its `Preflight
+tool <https://helpx.adobe.com/acrobat/using/correcting-problem-areas-preflight-tool.html>`__.

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+</svg>

docs/index.rst

@@ -0,0 +1,49 @@
+OCRmyPDF documentation
+======================
+
+.. figure:: images/logo.svg
+
+OCRmyPDF adds an optical character recognition (OCR) text layer to scanned PDF
+files, allowing them to be searched.
+
+PDF is the best format for storing and exchanging scanned documents.
+Unfortunately, PDFs can be difficult to modify. OCRmyPDF makes it easy to apply
+image processing and OCR to existing PDFs.
+
+.. toctree::
+   :maxdepth: 1
+
+   introduction
+   release_notes
+   installation
+   optimizer
+   languages
+   jbig2
+
+.. toctree::
+   :caption: Usage
+   :maxdepth: 2
+
+   cookbook
+   docker
+   advanced
+   batch
+   performance
+   pdfsecurity
+   errors
+
+.. toctree::
+   :caption: Developers
+   :maxdepth: 2
+
+   api
+   plugins
+   apiref
+   contributing
+
+Indices and tables
+==================
+
+* :ref:`genindex`
+* :ref:`modindex`
+* :ref:`search`

docs/installation.rst

@@ -0,0 +1,826 @@
+===================
+Installing OCRmyPDF
+===================
+
+.. |latest| image:: https://img.shields.io/pypi/v/ocrmypdf.svg
+    :alt: OCRmyPDF latest released version on PyPI
+
+|latest|
+
+The easiest way to install OCRmyPDF is to follow the steps for your operating
+system/platform. This version may be out of date, however.
+
+These platforms have one-liner installs:
+
++-------------------------------+-------------------------------+
+| Debian, Ubuntu                | ``apt install ocrmypdf``      |
++-------------------------------+-------------------------------+
+| Windows Subsystem for Linux   | ``apt install ocrmypdf``      |
++-------------------------------+-------------------------------+
+| Fedora                        | ``dnf install ocrmypdf``      |
++-------------------------------+-------------------------------+
+| macOS                         | ``brew install ocrmypdf``     |
++-------------------------------+-------------------------------+
+| LinuxBrew                     | ``brew install ocrmypdf``     |
++-------------------------------+-------------------------------+
+| FreeBSD                       | ``pkg install py38-ocrmypdf`` |
++-------------------------------+-------------------------------+
+| Conda (WSL, macOS, Linux)     | ``conda install ocrmypdf``    |
++-------------------------------+-------------------------------+
+
+More detailed procedures are outlined below. If you want to do a manual
+install, or install a more recent version than your platform provides, read on.
+
+.. contents:: Platform-specific steps
+    :depth: 2
+    :local:
+
+Installing on Linux
+===================
+
+Debian and Ubuntu 18.04 or newer
+--------------------------------
+
+.. |deb-stable| image:: https://repology.org/badge/version-for-repo/debian_stable/ocrmypdf.svg
+    :alt: Debian 9 stable ("stretch")
+
+.. |deb-testing| image:: https://repology.org/badge/version-for-repo/debian_testing/ocrmypdf.svg
+    :alt: Debian 10 testing ("buster")
+
+.. |deb-unstable| image:: https://repology.org/badge/version-for-repo/debian_unstable/ocrmypdf.svg
+    :alt: Debian unstable
+
+.. |ubu-1804| image:: https://repology.org/badge/version-for-repo/ubuntu_18_04/ocrmypdf.svg
+    :alt: Ubuntu 18.04 LTS
+
+.. |ubu-2004| image:: https://repology.org/badge/version-for-repo/ubuntu_20_04/ocrmypdf.svg
+    :alt: Ubuntu 20.04 LTS
+
+.. |ubu-2110| image:: https://repology.org/badge/version-for-repo/ubuntu_21_10/ocrmypdf.svg
+    :alt: Ubuntu 21.10
+
++-----------------------------------------------+
+| **OCRmyPDF versions in Debian & Ubuntu**      |
++-----------------------------------------------+
+| |latest|                                      |
++-----------------------------------------------+
+| |deb-stable| |deb-testing| |deb-unstable|     |
++-----------------------------------------------+
+| |ubu-1804| |ubu-2004| |ubu-2110|              |
++-----------------------------------------------+
+
+Users of Debian 9 ("stretch") or later, or Ubuntu 18.04 or later, including users
+of Windows Subsystem for Linux, may simply
+
+.. code-block:: bash
+
+    apt-get install ocrmypdf
+
+As indicated in the table above, Debian and Ubuntu releases may lag
+behind the latest version. If the version available for your platform is
+out of date, you could opt to install the latest version from source.
+See `Installing HEAD revision from
+sources <#installing-head-revision-from-sources>`__. Ubuntu 16.10 to 17.10
+inclusive also had ocrmypdf, but these versions are end of life.
+
+For full details on version availability for your platform, check the
+`Debian Package Tracker <https://tracker.debian.org/pkg/ocrmypdf>`__ or
+`Ubuntu launchpad.net <https://launchpad.net/ocrmypdf>`__.
+
+.. note::
+
+   OCRmyPDF for Debian and Ubuntu currently omit the JBIG2 encoder.
+   OCRmyPDF works fine without it but will produce larger output files.
+   If you build jbig2enc from source, ocrmypdf 7.0.0 and later will
+   automatically detect it (specifically the ``jbig2`` binary) on the
+   ``PATH``. To add JBIG2 encoding, see :ref:`jbig2`.
+
+Fedora
+------
+
+.. |fedora-34| image:: https://repology.org/badge/version-for-repo/fedora_34/ocrmypdf.svg
+    :alt: Fedora 34
+
+.. |fedora-35| image:: https://repology.org/badge/version-for-repo/fedora_35/ocrmypdf.svg
+    :alt: Fedora 35
+
+.. |fedora-rawhide| image:: https://repology.org/badge/version-for-repo/fedora_rawhide/ocrmypdf.svg
+    :alt: Fedore Rawhide
+
++-----------------------------------------------+
+| **OCRmyPDF version**                          |
++-----------------------------------------------+
+| |latest|                                      |
++-----------------------------------------------+
+| |fedora-34| |fedora-35| |fedora-rawhide|      |
++-----------------------------------------------+
+
+Users of Fedora 29 or later may simply
+
+.. code-block:: bash
+
+    dnf install ocrmypdf
+
+For full details on version availability, check the `Fedora Package
+Tracker <https://apps.fedoraproject.org/packages/ocrmypdf>`__.
+
+If the version available for your platform is out of date, you could opt
+to install the latest version from source. See `Installing HEAD revision
+from sources <#installing-head-revision-from-sources>`__.
+
+.. note::
+
+   OCRmyPDF for Fedora currently omits the JBIG2 encoder due to patent
+   issues. OCRmyPDF works fine without it but will produce larger output
+   files. If you build jbig2enc from source, ocrmypdf 7.0.0 and later
+   will automatically detect it on the ``PATH``. To add JBIG2 encoding,
+   see `Installing the JBIG2 encoder <jbig2>`__.
+
+.. _ubuntu-lts-latest:
+
+Installing the latest version on Ubuntu 20.04 LTS
+-------------------------------------------------
+
+Ubuntu 20.04 includes ocrmypdf 9.6.0 - you can install that with ``apt``. To
+install a more recent version, uninstall the system-provided version of
+ocrmypdf, and install the following dependencies:
+
+.. code-block:: bash
+
+    sudo apt-get -y remove ocrmypdf  # remove system ocrmypdf, if installed
+    sudo apt-get -y update
+    sudo apt-get -y install \
+        ghostscript \
+        icc-profiles-free \
+        libxml2 \
+        pngquant \
+        python3-pip \
+        tesseract-ocr \
+        zlib1g
+
+To install ocrmypdf for the system:
+
+.. code-block:: bash
+
+    pip3 install ocrmypdf
+
+To install for the current user only:
+
+.. code-block:: bash
+
+    export PATH=$HOME/.local/bin:$PATH
+    pip3 install --user ocrmypdf
+
+Ubuntu 18.04 LTS
+----------------
+
+Ubuntu 18.04 includes ocrmypdf 6.1.2 - you can install that with ``apt``, but
+it is quite old now. To install a more recent version, uninstall the old version
+of ocrmypdf, and install the following dependencies:
+
+.. code-block:: bash
+
+    sudo apt-get -y remove ocrmypdf
+    sudo apt-get -y update
+    sudo apt-get -y install \
+        ghostscript \
+        icc-profiles-free \
+        libxml2 \
+        pngquant \
+        python3-distutils \
+        python3-pkg-resources \
+        python3-reportlab \
+        qpdf \
+        tesseract-ocr \
+        zlib1g \
+        unpaper
+
+We will need a newer version of ``pip`` then was available for Ubuntu 18.04:
+
+.. code-block:: bash
+
+    wget https://bootstrap.pypa.io/get-pip.py && python3 get-pip.py
+
+Then install the most recent ocrmypdf for the local user and set the
+user's ``PATH`` to check for the user's Python packages.
+
+.. code-block:: bash
+
+    export PATH=$HOME/.local/bin:$PATH
+    python3 -m pip install --user ocrmypdf
+
+To add JBIG2 encoding, see :ref:`jbig2`.
+
+Ubuntu 16.04 LTS
+----------------
+
+No package is available for Ubuntu 16.04. OCRmyPDF 8.0 and newer require
+Python 3.7. Ubuntu 16.04 ships Python 3.5, but you can install Python
+3.7 on it. Or, you can skip Python 3.7 and install OCRmyPDF 7.x or older
+- for that procedure, please see the installation documentation for the
+version of OCRmyPDF you plan to use.
+
+**Install system packages for OCRmyPDF**
+
+.. code-block:: bash
+
+    sudo apt-get update
+    sudo apt-get install -y software-properties-common python-software-properties
+    sudo add-apt-repository -y \
+        ppa:jonathonf/python-3.7 \
+        ppa:alex-p/tesseract-ocr
+    sudo apt-get update
+    sudo apt-get install -y \
+        ghostscript \
+        libexempi3 \
+        libffi6 \
+        pngquant \
+        python3.7 \
+        qpdf \
+        tesseract-ocr \
+        unpaper
+
+This will install a Python 3.7 binary at ``/usr/bin/python3.7``
+alongside the system's Python 3.5. Do not remove the system Python. This
+will also install Tesseract 4.0 from a PPA, since the version available
+in Ubuntu 16.04 is too old for OCRmyPDF.
+
+Now install pip for Python 3.7. This will install the Python 3.7 version
+of ``pip`` at ``/usr/local/bin/pip``.
+
+.. code-block:: bash
+
+    curl https://bootstrap.pypa.io/get-pip.py | sudo python3.7
+
+**Install OCRmyPDF**
+
+OCRmyPDF requires the locale to be set for UTF-8. **On some minimal
+Ubuntu installations**, such as the Ubuntu 16.04 Docker images it may be
+necessary to set the locale.
+
+.. code-block:: bash
+
+    # Optional: Only need to set these if they are not already set
+    export LC_ALL=C.UTF-8
+    export LANG=C.UTF-8
+
+Now install OCRmyPDF for the current user, and ensure that the ``PATH``
+environment variable contains ``$HOME/.local/bin``.
+
+.. code-block:: bash
+
+    export PATH=$HOME/.local/bin:$PATH
+    pip3.7 install --user ocrmypdf
+
+To add JBIG2 encoding, see :ref:`jbig2`.
+
+Arch Linux (AUR)
+----------------
+
+.. image:: https://repology.org/badge/version-for-repo/aur/ocrmypdf.svg
+    :alt: ArchLinux
+    :target: https://repology.org/metapackage/ocrmypdf
+
+There is an `Arch User Repository (AUR) package for OCRmyPDF
+<https://aur.archlinux.org/packages/ocrmypdf/>`__.
+
+Installing AUR packages as root is not allowed, so you must first `setup a
+non-root user
+<https://wiki.archlinux.org/index.php/Users_and_groups#User_management>`__ and
+`configure sudo <https://wiki.archlinux.org/index.php/Sudo#Configuration>`__.
+The standard Docker image, ``archlinux/base:latest``, does **not** have a
+non-root user configured, so users of that image must follow these guides. If
+you are using a VM image, such as `the official Vagrant image
+<https://app.vagrantup.com/archlinux/boxes/archlinux>`__, this work may already
+be completed for you.
+
+Next you should install the `base-devel package group
+<https://www.archlinux.org/groups/x86_64/base-devel/>`__. This includes the
+standard tooling needed to build packages, such as a compiler and binary tools.
+
+.. code-block:: bash
+
+   sudo pacman -S base-devel
+
+Now you are ready to install the OCRmyPDF package.
+
+.. code-block:: bash
+
+   curl -O https://aur.archlinux.org/cgit/aur.git/snapshot/ocrmypdf.tar.gz
+   tar xvzf ocrmypdf.tar.gz
+   cd ocrmypdf
+   makepkg -sri
+
+At this point you will have a working install of OCRmyPDF, but the Tesseract
+install won’t include any OCR language data. You can install `the
+tesseract-data package group
+<https://www.archlinux.org/groups/any/tesseract-data/>`__ to add all supported
+languages, or use that package listing to identify the appropriate package for
+your desired language.
+
+.. code-block:: bash
+
+   sudo pacman -S tesseract-data-eng
+
+As an alternative to this manual procedure, consider using an `AUR helper
+<https://wiki.archlinux.org/index.php/AUR_helpers>`__. Such a tool will
+automatically fetch, build and install the AUR package, resolve dependencies
+(including dependencies on AUR packages), and ease the upgrade procedure.
+
+If you have any difficulties with installation, check the repository package
+page.
+
+.. note::
+
+    The OCRmyPDF AUR package currently omits the JBIG2 encoder. OCRmyPDF works
+    fine without it but will produce larger output files. The encoder is
+    available from `the jbig2enc-git AUR package
+    <https://aur.archlinux.org/packages/jbig2enc-git/>`__ and may be installed
+    using the same series of steps as for the installation OCRmyPDF AUR
+    package. Alternatively, it may be built manually from source following the
+    instructions in `Installing the JBIG2 encoder <jbig2>`__.  If JBIG2 is
+    installed, OCRmyPDF 7.0.0 and later will automatically detect it.
+
+Alpine Linux
+------------
+
+.. image:: https://repology.org/badge/version-for-repo/alpine_edge/ocrmypdf.svg
+    :alt: Alpine Linux
+    :target: https://repology.org/metapackage/ocrmypdf
+
+To install OCRmyPDF for Alpine Linux:
+
+.. code-block:: bash
+
+    apk add ocrmypdf
+
+Mageia 7
+--------
+
+There is no OS-level packaging available for Mageia, so you must install the
+dependencies:
+
+.. code-block:: bash
+
+    # As root user
+    urpmi.update -a
+    urpmi \
+        ghostscript \
+        icc-profiles-openicc \
+        jbig2dec \
+        pngquant \
+        python3-pip \
+        python3-distutils-extra \
+        python3-pkg-resources \
+        python3-reportlab \
+        qpdf \
+        tesseract \
+        tesseract-osd \
+        tesseract-eng \
+        tesseract-fra
+
+To install ocrmypdf for the system:
+
+.. code-block:: bash
+
+    # As root user
+    pip3 install ocrmypdf
+    ldconfig
+
+Or, to install for the current user only:
+
+.. code-block:: bash
+
+    export PATH=$HOME/.local/bin:$PATH
+    pip3 install --user ocrmypdf
+
+Other Linux packages
+--------------------
+
+See the
+`Repology <https://repology.org/metapackage/ocrmypdf/versions>`__ page.
+
+In general, first install the OCRmyPDF package for your system, then
+optionally use the procedure `Installing with Python
+pip <#installing-with-python-pip>`__ to install a more recent version.
+
+Installing on macOS
+===================
+
+Homebrew
+--------
+
+.. image:: https://img.shields.io/homebrew/v/ocrmypdf.svg
+    :alt: homebrew
+    :target: http://brewformulas.org/Ocrmypdf
+
+OCRmyPDF is now a standard `Homebrew <https://brew.sh>`__ formula. To
+install on macOS:
+
+.. code-block:: bash
+
+    brew install ocrmypdf
+
+This will include only the English language pack. If you need other
+languages you can optionally install them all:
+
+.. code-block:: bash
+
+    brew install tesseract-lang  # Optional: Install all language packs
+
+.. note::
+
+   Users who previously installed OCRmyPDF on macOS using
+   ``pip install ocrmypdf`` should remove the pip version
+   (``pip3 uninstall ocrmypdf``) before switching to the Homebrew
+   version.
+
+.. note::
+
+   Users who previously installed OCRmyPDF from the private tap should
+   switch to the mainline version (``brew untap jbarlow83/ocrmypdf``)
+   and install from there.
+
+Manual installation on macOS
+----------------------------
+
+These instructions probably work on all macOS supported by Homebrew, and are
+for installing a more current version of OCRmyPDF than is available from
+Homebrew. Note that the Homebrew versions usually track the release versions
+fairly closely.
+
+If it's not already present, `install Homebrew <http://brew.sh/>`__.
+
+Update Homebrew:
+
+.. code-block:: bash
+
+    brew update
+
+Install or upgrade the required Homebrew packages, if any are missing.
+To do this, use ``brew edit ocrmypdf`` to obtain a recent list of Homebrew
+dependencies. You could also check the ``.workflows/build.yml``.
+
+This will include the English, French, German and Spanish language
+packs. If you need other languages you can optionally install them all:
+
+.. _macos-all-languages:
+
+   .. code-block:: bash
+
+    brew install tesseract-lang  # Option 2: for all language packs
+
+Update the homebrew pip:
+
+.. code-block:: bash
+
+    pip3 install --upgrade pip
+
+You can then install OCRmyPDF from PyPI, for the current user:
+
+.. code-block:: bash
+
+    pip3 install --user ocrmypdf
+
+or system-wide:
+
+.. code-block:: bash
+
+    pip3 install ocrmypdf
+
+The command line program should now be available:
+
+.. code-block:: bash
+
+    ocrmypdf --help
+
+Installing on Windows
+=====================
+
+Native Windows
+--------------
+
+.. note::
+
+    Administrator privileges will be required for some of these steps.
+
+You must install the following for Windows:
+
+* Python 3.7 (64-bit) or later
+* Tesseract 4.0 or later
+* Ghostscript 9.50 or later
+
+Using the `Chocolatey <https://chocolatey.org/>`_ package manager, install the
+following when running in an Administrator command prompt:
+
+* ``choco install python3``
+* ``choco install --pre tesseract``
+* ``choco install ghostscript``
+* ``choco install pngquant`` (optional)
+
+The commands above will install Python 3.x (latest version), Tesseract, Ghostscript
+and pngquant. Chocolatey may also need to install the Windows Visual C++ Runtime
+DLLs or other Windows patches, and may require a reboot.
+
+You may then use ``pip`` to install ocrmypdf. (This can performed by a user or
+Administrator.):
+
+* ``pip install ocrmypdf``
+
+Chocolatey automatically selects appropriate versions of these applications. If you
+are installing them manually, please install 64-bit versions of all applications for
+64-bit Windows, or 32-bit versions of all applications for 32-bit Windows. Mixing
+the "bitness" of these programs will lead to errors.
+
+OCRmyPDF will check the Windows Registry and standard locations in your Program Files
+for third party software it needs (specifically, Tesseract and Ghostscript). To
+override the versions OCRmyPDF selects, you can modify the ``PATH`` environment
+variable. `Follow these directions <https://www.computerhope.com/issues/ch000549.htm#dospath>`_
+to change the PATH.
+
+.. warning::
+
+    As of early 2021, users have reported problems with the Microsoft Store version of
+    Python and OCRmyPDF. These issues affect many other third party Python packages.
+    Please download Python from Python.org or Chocolatey instead, and do not use the
+    Microsoft Store version.
+
+Windows Subsystem for Linux
+---------------------------
+
+#. Install Ubuntu 20.04 for Windows Subsystem for Linux, if not already installed.
+#. Follow the procedure to install :ref:`OCRmyPDF on Ubuntu 20.04 <ubuntu-lts-latest>`.
+#. Open the Windows command prompt and create a symlink:
+
+.. code-block:: powershell
+
+    wsl sudo ln -s  /home/$USER/.local/bin/ocrmypdf /usr/local/bin/ocrmypdf
+
+Then confirm that the expected version from PyPI (|latest|) is installed:
+
+.. code-block:: powershell
+
+    wsl ocrmypdf --version
+
+You can then run OCRmyPDF in the Windows command prompt or Powershell, prefixing
+``wsl``, and call it from Windows programs or batch files.
+
+Cygwin64
+--------
+
+First install the the following prerequisite Cygwin packages using ``setup-x86_64.exe``::
+
+    python37 (or later)
+    python3?-devel
+    python3?-pip
+    python3?-lxml
+    python3?-imaging
+
+       (where 3? means match the version of python3 you installed)
+
+    gcc-g++
+    ghostscript (<=9.50 or >=9.52-2 see note below)
+    libexempi3
+    libexempi-devel
+    libffi6
+    libffi-devel
+    pngquant
+    qpdf
+    libqpdf-devel
+    tesseract-ocr
+    tesseract-ocr-devel
+
+.. note::
+
+    The Cygwin package for Ghostscript in versions 9.52 and
+    9.52-1 contained a bug that caused an exception to occur when
+    ocrmypdf invoked gs.  Make sure you have either 9.50 (or earlier)
+    or 9.52-2 (or later).
+
+Then open a Cygwin terminal (i.e. ``mintty``), run the following commands. Note
+that if you are using the version of ``pip`` that was installed with the Cygwin
+Python package, the command name will be ``pip3``.  If you have since updated
+``pip`` (with, for instance ``pip3 install --upgrade pip``) the the command is
+likely just ``pip`` instead of ``pip3``:
+
+.. code-block:: bash
+
+    pip3 install wheel
+    pip3 install ocrmypdf
+
+The optional dependency "unpaper" that is currently not available under Cygwin.
+Without it, certain options such as ``--clean`` will produce an error message.
+However, the OCR-to-text-layer functionality is available.
+
+Docker
+------
+
+You can also :ref:`Install the Docker <docker>` container on Windows. Ensure that
+your command prompt can run the docker "hello world" container.
+
+Installing on FreeBSD
+=====================
+
+.. image:: https://repology.org/badge/version-for-repo/freebsd/python:ocrmypdf.svg
+    :alt: FreeBSD
+    :target: https://repology.org/project/python:ocrmypdf/versions
+
+FreeBSD 11.3, 12.0, 12.1-RELEASE and 13.0-CURRENT are supported. Other
+versions likely work but have not been tested.
+
+.. code-block:: bash
+
+    pkg install py38-ocrmypdf
+
+To install a more recent version, you could attempt to first install the system
+version with ``pkg``, then use ``pip install --user ocrmypdf``.
+
+Installing the Docker image
+===========================
+
+For some users, installing the Docker image will be easier than
+installing all of OCRmyPDF's dependencies.
+
+See :ref:`docker` for more information.
+
+Installing with Python pip
+==========================
+
+OCRmyPDF is delivered by PyPI because it is a convenient way to install
+the latest version. However, PyPI and ``pip`` cannot address the fact
+that ``ocrmypdf`` depends on certain non-Python system libraries and
+programs being installed.
+
+.. warning::
+
+    Debian and Ubuntu users: unfortunately, Debian and Ubuntu customize
+    Python in non-standard ways, and the nature of these customizations
+    varies from release to release. This can make for a frustrating
+    user experience. The instructions below work on almost all platforms that
+    have Python installed, except for Debian and Ubuntu, where you may need
+    to take additional steps. For best results on Debian and Ubuntu, use the
+    ``apt`` packages; or if these are too old, run
+    ``apt install python3-pip python3-venv``, create a virtual environment,
+    and install OCRmyPDF in that environment.
+
+    `See here for more inforation on Debian-Python issues
+    <https://gist.github.com/tiran/2dec9e03c6f901814f6d1e8dad09528e>`__.
+
+For best results, first install `your platform's
+version <https://repology.org/metapackage/ocrmypdf/versions>`__ of
+``ocrmypdf``, using the instructions elsewhere in this document. Then
+you can use ``pip`` to get the latest version if your platform version
+is out of date. Chances are that this will satisfy most dependencies.
+
+Use ``ocrmypdf --version`` to confirm what version was installed.
+
+Then you can install the latest OCRmyPDF from the Python wheels. First
+try:
+
+.. code-block:: bash
+
+    pip3 install --user ocrmypdf
+
+You should then be able to run ``ocrmypdf --version`` and see that the
+latest version was located.
+
+Since ``pip3 install --user`` does not work correctly on some platforms,
+notably Ubuntu 16.04 and older, and the Homebrew version of Python,
+instead use this for a system wide installation:
+
+.. code-block:: bash
+
+    pip3 install ocrmypdf
+
+.. note::
+
+    AArch64 (ARM64) users: this process will be difficult because most
+    Python packages are not available as binary wheels for your platform.
+    You're probably better off using a platform install on Debian, Ubuntu,
+    or Fedora.
+
+Requirements for pip and HEAD install
+-------------------------------------
+
+OCRmyPDF currently requires these external programs and libraries to be
+installed, and must be satisfied using the operating system package
+manager. ``pip`` cannot provide them.
+
+-  Python 3.7 or newer
+-  Ghostscript 9.15 or newer
+-  Tesseract 4.0.0-beta or newer
+
+As of ocrmypdf 7.2.1, the following versions are recommended:
+
+-  Python 3.9 or newer
+-  Ghostscript 9.23 or newer
+-  Tesseract 4.0.0 or newer
+-  jbig2enc 0.29 or newer
+-  pngquant 2.5 or newer
+-  unpaper 6.1
+
+jbig2enc, pngquant, and unpaper are optional. If missing certain
+features are disabled. OCRmyPDF will discover them as soon as they are
+available.
+
+**jbig2enc**, if present, will be used to optimize the encoding of
+monochrome images. This can significantly reduce the file size of the
+output file. It is not required.
+`jbig2enc <https://github.com/agl/jbig2enc>`__ is not generally
+available for Ubuntu or Debian due to lingering concerns about patent
+issues, but can easily be built from source. To add JBIG2 encoding, see
+:ref:`jbig2`.
+
+**pngquant**, if present, is optionally used to optimize the encoding of
+PNG-style images in PDFs (actually, any that are that losslessly
+encoded) by lossily quantizing to a smaller color palette. It is only
+activated then the ``--optimize`` argument is ``2`` or ``3``.
+
+**unpaper**, if present, enables the ``--clean`` and ``--clean-final``
+command line options.
+
+These are in addition to the Python packaging dependencies, meaning that
+unfortunately, the ``pip install`` command cannot satisfy all of them.
+
+Installing HEAD revision from sources
+=====================================
+
+If you have ``git`` and Python 3.7 or newer installed, you can install
+from source. When the ``pip`` installer runs, it will alert you if
+dependencies are missing.
+
+If you prefer to build every from source, you will need to `build
+pikepdf from
+source <https://pikepdf.readthedocs.io/en/latest/installation.html#building-from-source>`__.
+First ensure you can build and install pikepdf.
+
+To install the HEAD revision from sources in the current Python 3
+environment:
+
+.. code-block:: bash
+
+    pip3 install git+https://github.com/jbarlow83/OCRmyPDF.git
+
+Or, to install in `development
+mode <https://pythonhosted.org/setuptools/setuptools.html#development-mode>`__,
+allowing customization of OCRmyPDF, use the ``-e`` flag:
+
+.. code-block:: bash
+
+    pip3 install -e git+https://github.com/jbarlow83/OCRmyPDF.git
+
+You may find it easiest to install in a virtual environment, rather than
+system-wide:
+
+.. code-block:: bash
+
+    git clone -b master https://github.com/jbarlow83/OCRmyPDF.git
+    python3 -m venv
+    source venv/bin/activate
+    cd OCRmyPDF
+    pip3 install .
+
+However, ``ocrmypdf`` will only be accessible on the system PATH when
+you activate the virtual environment.
+
+To run the program:
+
+.. code-block:: bash
+
+    ocrmypdf --help
+
+If not yet installed, the script will notify you about dependencies that
+need to be installed. The script requires specific versions of the
+dependencies. Older version than the ones mentioned in the release notes
+are likely not to be compatible to OCRmyPDF.
+
+For development
+---------------
+
+To install all of the development and test requirements:
+
+.. code-block:: bash
+
+    git clone -b master https://github.com/jbarlow83/OCRmyPDF.git
+    python3 -m venv
+    source venv/bin/activate
+    cd OCRmyPDF
+    pip install -e .[test]
+
+To add JBIG2 encoding, see :ref:`jbig2`.
+
+Shell completions
+=================
+
+Completions for ``bash`` and ``fish`` are available in the project's
+``misc/completion`` folder. The ``bash`` completions are likely ``zsh``
+compatible but this has not been confirmed. Package maintainers, please
+install these at the appropriate locations for your system.
+
+To manually install the ``bash`` completion, copy
+``misc/completion/ocrmypdf.bash`` to ``/etc/bash_completion.d/ocrmypdf``
+(rename the file).
+
+To manually install the ``fish`` completion, copy
+``misc/completion/ocrmypdf.fish`` to
+``~/.config/fish/completions/ocrmypdf.fish``.

docs/introduction.rst

@@ -0,0 +1,239 @@
+============
+Introduction
+============
+
+OCRmyPDF is an application and library that adds text "layers" to images
+in PDFs, making scanned image PDFs searchable. It uses OCR to guess what text
+is contained in images. It is written in Python. OCRmyPDF supports plugins
+that allow customization of its processing steps, and is very tolerant of
+PDFs that contain scanned images and "born digital" content that needs no
+text recognition.
+
+About OCR
+=========
+
+`Optical character
+recognition <https://en.wikipedia.org/wiki/Optical_character_recognition>`__
+is technology that converts images of typed or handwritten text, such as
+in a scanned document, to computer text that can be selected, searched and copied.
+
+OCRmyPDF uses
+`Tesseract <https://github.com/tesseract-ocr/tesseract>`__, the best
+available open source OCR engine, to perform OCR.
+
+.. _raster-vector:
+
+About PDFs
+==========
+
+PDFs are page description files that attempts to preserve a layout
+exactly. They contain `vector
+graphics <http://vector-conversions.com/vectorizing/raster_vs_vector.html>`__
+that can contain raster objects such as scanned images. Because PDFs can
+contain multiple pages (unlike many image formats) and can contain fonts
+and text, it is a good format for exchanging scanned documents.
+
+|image|
+
+A PDF page might contain multiple images, even if it only appears to
+have one image. Some scanners or scanning software will segment pages
+into monochromatic text and color regions for example, to improve the
+compression ratio and appearance of the page.
+
+Rasterizing a PDF is the process of generating corresponding raster images.
+OCR engines like Tesseract work with images, not scalable vector graphics
+or mixed raster-vector-text graphics such as PDF.
+
+About PDF/A
+===========
+
+`PDF/A <https://en.wikipedia.org/wiki/PDF/A>`__ is an ISO-standardized
+subset of the full PDF specification that is designed for archiving (the
+'A' stands for Archive). PDF/A differs from PDF primarily by omitting
+features that would make it difficult to read the file in the future,
+such as embedded Javascript, video, audio and references to external
+fonts. All fonts and resources needed to interpret the PDF must be
+contained within it. Because PDF/A disables Javascript and other types
+of embedded content, it is probably more secure.
+
+There are various conformance levels and versions, such as "PDF/A-2b".
+
+Generally speaking, the best format for scanned documents is PDF/A. Some
+governments and jurisdictions, US Courts in particular, `mandate the use
+of PDF/A <https://pdfblog.com/2012/02/13/what-is-pdfa/>`__ for scanned
+documents.
+
+Since most people who scan documents are interested in reading them
+indefinitely into the future, OCRmyPDF generates PDF/A-2b by default.
+
+PDF/A has a few drawbacks. Some PDF viewers include an alert that the
+file is a PDF/A, which may confuse some users. It also tends to produce
+larger files than PDF, because it embeds certain resources even if they
+are commonly available. PDF/A files can be digitally signed, but may not
+be encrypted, to ensure they can be read in the future. Fortunately,
+converting from PDF/A to a regular PDF is trivial, and any PDF viewer
+can view PDF/A.
+
+What OCRmyPDF does
+==================
+
+OCRmyPDF analyzes each page of a PDF to determine the colorspace and
+resolution (DPI) needed to capture all of the information on that page
+without losing content. It uses
+`Ghostscript <http://ghostscript.com/>`__ to rasterize the page, and
+then performs on OCR the rasterized image to create an OCR "layer".
+The layer is then grafted back onto the original PDF.
+
+While one can use a program like Ghostscript or ImageMagick to get an
+image and put the image through Tesseract, that actually creates a new
+PDF and many details may be lost. OCRmyPDF can produce a minimally
+changed PDF as output.
+
+OCRmyPDF also provides some image processing options, like deskew, which
+improves the appearance of files and quality of OCR. When these are used,
+the OCR layer is grafted onto the processed image instead.
+
+By default, OCRmyPDF produces archival PDFs – PDF/A, which are a
+stricter subset of PDF features designed for long term archives. If
+regular PDFs are desired, this can be disabled with
+``--output-type pdf``.
+
+Why you shouldn't do this manually
+==================================
+
+A PDF is similar to an HTML file, in that it contains document structure
+along with images. Sometimes a PDF does nothing more than present a full
+page image, but often there is additional content that would be lost.
+
+A manual process could work like either of these:
+
+1. Rasterize each page as an image, OCR the images, and combine the
+   output into a PDF. This preserves the layout of each page, but
+   resamples all images (possibly losing quality, increasing file size,
+   introducing compression artifacts, etc.).
+2. Extract each image, OCR, and combine the output into a PDF. This
+   loses the context in which images are used in the PDF, meaning that
+   cropping, rotation and scaling of pages may be lost. Some scanned
+   PDFs use multiple images segmented into black and white, grayscale
+   and color regions, with stencil masks to prevent overlap, as this can
+   enhance the appearance of a file while reducing file size. Clearly,
+   reassembling these images will be easy. This also loses and text or
+   vector art on any pages in a PDF with both scanned and pure digital
+   content.
+
+In the case of a PDF that is nothing other than a container of images
+(no rotation, scaling, cropping, one image per page), the second
+approach can be lossless.
+
+OCRmyPDF uses several strategies depending on input options and the
+input PDF itself, but generally speaking it rasterizes a page for OCR
+and then grafts the OCR back onto the original. As such it can handle
+complex PDFs and still preserve their contents as much as possible.
+
+OCRmyPDF also supports a many, many edge cases that have cropped over
+several years of development. We support PDF features like images inside
+of Form XObjects, and pages with UserUnit scaling. We support rare image
+formats like non-monochrome 1-bit images. We warn about files you may
+not to OCR. Thanks to pikepdf and QPDF, we auto-repair PDFs that are
+damaged. (Not that you need to know what any of these are! You should be
+able to throw any PDF at it.)
+
+Limitations
+===========
+
+OCRmyPDF is limited by the Tesseract OCR engine. As such it experiences
+these limitations, as do any other programs that rely on Tesseract:
+
+-  The OCR is not as accurate as commercial OCR solutions.
+-  It is not capable of recognizing handwriting.
+-  It may find gibberish and report this as OCR output.
+-  If a document contains languages outside of those given in the
+   ``-l LANG`` arguments, results may be poor.
+-  It is not always good at analyzing the natural reading order of
+   documents. For example, it may fail to recognize that a document
+   contains two columns, and may try to join text across columns.
+-  Poor quality scans may produce poor quality OCR. Garbage in, garbage
+   out.
+-  It does not expose information about what font family text belongs
+   to.
+
+OCRmyPDF is also limited by the PDF specification:
+
+-  PDF encodes the position of text glyphs but does not encode document
+   structure. There is no markup that divides a document in sections,
+   paragraphs, sentences, or even words (since blank spaces are not
+   represented). As such all elements of document structure including
+   the spaces between words must be derived heuristically. Some PDF
+   viewers do a better job of this than others.
+-  Because some popular open source PDF viewers have a particularly hard
+   time with spaces between words, OCRmyPDF appends a space to each text
+   element as a workaround (when using ``--pdf-renderer hocr``). While
+   this mixes document structure with graphical information that ideally
+   should be left to the PDF viewer to interpret, it improves
+   compatibility with some viewers and does not cause problems for
+   better ones.
+
+Ghostscript also imposes some limitations:
+
+-  PDFs containing JBIG2-encoded content will be converted to CCITT
+   Group4 encoding, which has lower compression ratios, if Ghostscript
+   PDF/A is enabled.
+-  PDFs containing JPEG 2000-encoded content will be converted to JPEG
+   encoding, which may introduce compression artifacts, if Ghostscript
+   PDF/A is enabled.
+-  Ghostscript may transcode grayscale and color images, either lossy to
+   lossless or lossless to lossy, based on an internal algorithm. This
+   behavior can be suppressed by setting ``--pdfa-image-compression`` to
+   ``jpeg`` or ``lossless`` to set all images to one type or the other.
+   Ghostscript has no option to maintain the input image's format.
+   (Ghostscript 9.25+ can copy JPEG images without transcoding them;
+   earlier versions will transcode.)
+-  Ghostscript's PDF/A conversion removes any XMP metadata that is not
+   one of the standard XMP metadata namespaces for PDFs. In particular,
+   PRISM Metdata is removed.
+-  Ghostscript's PDF/A conversion seems to remove or deactivate
+   hyperlinks and other active content.
+
+You can use ``--output-type pdf`` to disable PDF/A conversion and produce
+a standard, non-archival PDF.
+
+Regarding OCRmyPDF itself:
+
+-  PDFs that use transparency are not currently represented in the test
+   suite
+
+Similar programs
+================
+
+To the author's knowledge, OCRmyPDF is the most feature-rich and
+thoroughly tested command line OCR PDF conversion tool. If it does not
+meet your needs, contributions and suggestions are welcome. If not,
+consider one of these similar open source programs:
+
+-  pdf2pdfocr
+-  pdfsandwich
+
+Ghostscript recently added three "pdfocr" output devices. They work by
+rasterizing all content and converting all pages to a single colour space.
+
+Web front-ends
+==============
+
+The Docker image ``ocrmypdf`` provides a web service front-end
+that allows files to submitted over HTTP and the results "downloaded".
+This is an HTTP server intended to simplify web services deployments; it
+is not intended to be deployed on the public internet and no real
+security measures to speak of.
+
+In addition, the following third-party integrations are available:
+
+-  `Nextcloud OCR <https://github.com/janis91/ocr>`__ is a free software
+   plugin for the Nextcloud private cloud software
+
+OCRmyPDF is not designed to be secure against malware-bearing PDFs (see
+`Using OCRmyPDF online <ocr-service>`__). Users should ensure they
+comply with OCRmyPDF's licenses and the licenses of all dependencies. In
+particular, OCRmyPDF requires Ghostscript, which is licensed under
+AGPLv3.
+
+.. |image| image:: images/bitmap_vs_svg.svg

docs/jbig2.rst

@@ -0,0 +1,55 @@
+.. _jbig2:
+
+============================
+Installing the JBIG2 encoder
+============================
+
+Most Linux distributions do not include a JBIG2 encoder since JBIG2
+encoding was patented for a long time. All known JBIG2 US patents have
+expired as of 2017, but it is possible that unknown patents exist.
+
+JBIG2 encoding is recommended for OCRmyPDF and is used to losslessly
+create smaller PDFs. If JBIG2 encoding is not available, lower quality
+encodings will be used.
+
+JBIG2 decoding is not patented and is performed automatically by most
+PDF viewers. It is widely supported and has been part of the PDF
+specification since 2001.
+
+On macOS, Homebrew packages jbig2enc and OCRmyPDF includes it by
+default. The Docker image for OCRmyPDF also builds its own JBIG2 encoder
+from source.
+
+For all other Linux, you must build a JBIG2 encoder from source:
+
+.. code-block:: bash
+
+   git clone https://github.com/agl/jbig2enc
+   cd jbig2enc
+   ./autogen.sh
+   ./configure && make
+   [sudo] make install
+
+.. _jbig2-lossy:
+
+Lossy mode JBIG2
+================
+
+OCRmyPDF provides lossy mode JBIG2 as an advanced feature. Users should
+`review the technical concerns with JBIG2 in lossy
+mode <https://en.wikipedia.org/wiki/JBIG2#Disadvantages>`__
+and decide if this feature is acceptable for their use case.
+
+JBIG2 lossy mode does achieve higher compression ratios than any other
+monochrome (bitonal) compression technology; for large text documents
+the savings are considerable. JBIG2 lossless still gives great
+compression ratios and is a major improvement over the older CCITT G4
+standard. As explained above, there is some risk of substitution errors.
+
+To turn on JBIG2 lossy mode, add the argument ``--jbig2-lossy``.
+``--optimize {1,2,3}`` are necessary for the argument to take effect
+also required. Also, a JBIG2 encoder must be installed as described in
+the previous section.
+
+*Due to an oversight, ocrmypdf v7.0 and v7.1 used lossy mode by
+default.*

docs/languages.rst

@@ -0,0 +1,76 @@
+.. _lang-packs:
+
+====================================
+Installing additional language packs
+====================================
+
+OCRmyPDF uses Tesseract for OCR, and relies on its language packs for all languages.
+On most platforms, English is installed with Tesseract by default, but not always.
+
+Tesseract supports `most
+languages <https://github.com/tesseract-ocr/tesseract/blob/master/doc/tesseract.1.asc#languages>`__.
+Languages are identified by standardized three-letter codes (called ISO 639-2 Alpha-3).
+Tesseract's documentation also lists the three-letter code for your language.
+Some are anglicized, e.g. Spanish is ``spa`` rather than ``esp``, while others
+are not, e.g. German is ``deu`` and French is ``fra``.
+
+After you have installed a language pack, you can use it with ``ocrmypdf -l <language>``,
+for example ``ocrmypdf -l spa``. For multilingual documents, you can specify
+all languages to be expected, e.g. ``ocrmypdf -l eng+fra`` for English and French.
+English is assumed by default unless other language(s) are specified.
+
+For Linux users, you can often find packages that provide language
+packs:
+
+Debian and Ubuntu users
+=======================
+
+.. code-block:: bash
+
+   # Display a list of all Tesseract language packs
+   apt-cache search tesseract-ocr
+
+   # Install Chinese Simplified language pack
+   apt-get install tesseract-ocr-chi-sim
+
+You can then pass the ``-l LANG`` argument to OCRmyPDF to give a hint as
+to what languages it should search for. Multiple languages can be
+requested using either ``-l eng+fra`` (English and French) or
+``-l eng -l fra``.
+
+Fedora users
+============
+
+.. code-block:: bash
+
+   # Display a list of all Tesseract language packs
+   dnf search tesseract
+
+   # Install Chinese Simplified language pack
+   dnf install tesseract-langpack-chi_sim
+
+You can then pass the ``-l LANG`` argument to OCRmyPDF to give a hint as
+to what languages it should search for. Multiple languages can be
+requested using either ``-l eng+fra`` (English and French) or
+``-l eng -l fra``.
+
+macOS users
+===========
+
+You can install additional language packs by
+:ref:`installing Tesseract using Homebrew with all language packs <macos-all-languages>`.
+
+Docker users
+============
+
+Users of the OCRmyPDF Docker image should install language packs into a
+derived Docker image as
+:ref:`described in that section <docker-lang-packs>`.
+
+Windows users
+=============
+
+The Tesseract installer provided by Chocolatey currently includes only English language. 
+To install other languages, download the respective language pack (``.traineddata`` file) 
+from https://github.com/tesseract-ocr/tessdata/ and place it in 
+``C:\\Program Files\\Tesseract-OCR\\tessdata`` (or wherever Tesseract OCR is installed).

docs/optimizer.rst

@@ -0,0 +1,75 @@
+================
+PDF optimization
+================
+
+OCRmyPDF includes an image-oriented PDF optimizer. By default, the optimizer
+runs with safe settings with the goal of improving compression at no loss of
+quality. At higher optimization levels, lossy optimizations may be applied and
+tuned. Optimization occurs after OCR, and only if OCR succeeded.  It does not
+perform other possible optimizations such as deduplicating resources,
+consolidating fonts, simplifying vector drawings, or anything of that nature.
+
+Optimization ranges from ``-O0`` through ``-O3``, where ``0`` disables
+optimization and ``3`` implements all options. ``1``, the default, performs only
+safe and lossless optimizations. (This is similar to GCC's optimization
+parameter.) The exact type of optimizations performed will vary over time.
+
+PDF optimization requires third-party, optional tools for certain optimizations.
+If these are not installed or cannot be found by OCRmyPDF, optimization will not
+be as good.
+
+Optimizations that always occurs
+================================
+
+OCRmyPDF will automatically replace obsolete or inferior compression schemes
+such as RLE or LZW with superior schemes such as Deflate and converting
+monochrome images to CCITT G4. Since this is harmless it always occurs and there
+is no way to disable it. Other non-image compressed objects are compressed as
+well.
+
+Fast web view
+=============
+
+OCRmyPDF automatically optimizes PDFs for "fast web view" in Adobe Acrobat's
+parlance, or equivalently, linearizes PDFs so that the resources they reference
+are presented in the order a viewer needs them for sequential display. This
+reduces the latency of viewing a PDF both online and from local storage. This
+actually slightly increases the file size.
+
+To disable this optimization and all others, use ``ocrmypdf --optimize 0 ...``
+or the shorthand ``-O0``.
+
+Lossless optimizations
+======================
+
+At optimization level ``-O1`` (the default), OCRmyPDF will also attempt lossless
+image optimization.
+
+If a JBIG2 encoder is available, then monochrome images will be converted to
+JBIG2, with the potential for huge savings on large black and white images,
+since JBIG2 is far more efficient than any other monochrome (bi-level)
+compression. (All known US patents related to JBIG2 have probably expired, but
+it remains the responsibility of the user to supply a JBIG2 encoder such as
+`jbig2enc <https://github.com/agl/jbig2enc>`__. OCRmyPDF does not implement
+JBIG2 encoding on its own.)
+
+OCRmyPDF currently does not attempt to recompress losslessly compressed objects
+more aggressively.
+
+Lossy optimizations
+===================
+
+At optimization level ``-O2`` and ``-O3``, OCRmyPDF will some attempt lossy
+image optimization.
+
+If ``pngquant`` is installed, OCRmyPDF will use it to perform quantize paletted
+images to reduce their size.
+
+The quality of JPEGs may be lowered, on the assumption that a lower quality
+image may be suitable for storage after OCR.
+
+It is not possible to optimize all image types. Uncommon image types may be
+skipped by the optimizer.
+
+OCRmyPDF provides :ref:`lossy mode JBIG2 <jbig2-lossy>` as an advanced feature
+that additional requires the argument ``--jbig2-lossy``.

docs/pdfsecurity.rst

@@ -0,0 +1,162 @@
+===================
+PDF security issues
+===================
+
+   OCRmyPDF should only be used on PDFs you trust. It is not designed to
+   protect you against malware.
+
+Recognizing that many users have an interest in handling PDFs and
+applying OCR to PDFs they did not generate themselves, this article
+discusses the security implications of PDFs and how users can protect
+themselves.
+
+The disclaimer applies: this software has no warranties of any kind.
+
+PDFs may contain malware
+========================
+
+PDF is a rich, complex file format. The official PDF 1.7 specification,
+ISO 32000:2008, is hundreds of pages long and references several annexes
+each of which are similar in length. PDFs can contain video, audio, XML,
+JavaScript and other programming, and forms. In some cases, they can
+open internet connections to pre-selected URLs. All of these are possible
+attack vectors.
+
+In short, PDFs `may contain
+viruses <https://security.stackexchange.com/questions/64052/can-a-pdf-file-contain-a-virus>`__.
+
+This
+`article <https://theinvisiblethings.blogspot.ca/2013/02/converting-untrusted-pdfs-into-trusted.html>`__
+describes a high-paranoia method which allows potentially hostile PDFs
+to be viewed and rasterized safely in a disposable virtual machine. A
+trusted PDF created in this manner is converted to images and loses all
+information making it searchable and losing all compression. OCRmyPDF
+could be used to restore searchability.
+
+How OCRmyPDF processes PDFs
+===========================
+
+OCRmyPDF must open and interpret your PDF in order to insert an OCR
+layer. First, it runs all PDFs through
+`pikepdf <https://github.com/pikepdf/pikepdf>`__, a library based on
+`qpdf <https://github.com/qpdf/qpdf>`__, a program that repairs PDFs
+with syntax errors. This is done because, in the author's experience, a
+significant number of PDFs in the wild, especially those created by
+scanners, are not well-formed files. qpdf makes it more likely that
+OCRmyPDF will succeed, but offers no security guarantees. qpdf is also
+used to split the PDF into single page PDFs.
+
+Finally, OCRmyPDF rasterizes each page of the PDF using
+`Ghostscript <http://ghostscript.com/>`__ in ``-dSAFER`` mode.
+
+Depending on the options specified, OCRmyPDF may graft the OCR layer
+into the existing PDF or it may essentially reconstruct ("re-fry") a
+visually identical PDF that may be quite different at the binary level.
+That said, OCRmyPDF is not a tool designed for sanitizing PDFs.
+
+.. _ocr-service:
+
+Using OCRmyPDF online or as a service
+=====================================
+
+OCRmyPDF is not designed for use as a public web service where a
+malicious user could upload a chosen PDF. In particular, it is not
+necessarily secure against PDF malware or PDFs that cause denial of
+service. OCRmyPDF relies on Ghostscript, and therefore, if deployed
+online one should be prepared to comply with Ghostscript's Affero GPL
+license, and any other licenses.
+
+Setting aside these concerns, a side effect of OCRmyPDF is that it may
+incidentally sanitize PDFs containing certain types of malware. It
+repairs the PDF with pikepdf/libqpdf, which could correct malformed PDF
+structures that are part of an attack. When PDF/A output is selected
+(the default), the input PDF is partially reconstructed by Ghostscript.
+When ``--force-ocr`` is used, all pages are rasterized and reconverted
+to PDF, which could remove malware in embedded images.
+
+OCRmyPDF should be relatively safe to use in a trusted intranet, with
+some considerations:
+
+Limiting CPU usage
+------------------
+
+OCRmyPDF will attempt to use all available CPUs and storage, so
+executing ``nice ocrmypdf`` or limiting the number of jobs with the
+``-j`` argument may ensure the server remains available. Another option
+would be to run OCRmyPDF jobs inside a Docker container, a virtual machine,
+or a cloud instance, which can impose its own limits on CPU usage and be
+terminated "from orbit" if it fails to complete.
+
+Temporary storage requirements
+------------------------------
+
+OCRmyPDF will use a large amount of temporary storage for its work,
+proportional to the total number of pixels needed to rasterize the PDF.
+The raster image of a 8.5×11" color page at 300 DPI takes 25 MB
+uncompressed; OCRmyPDF saves its intermediates as PNG, but that still
+means it requires about 9 MB per intermediate based on average
+compression ratios. Multiple intermediates per page are also required,
+depending on the command line given. A rule of thumb would be to allow
+100 MB of temporary storage per page in a file – meaning that a small
+cloud servers or small VM partitions should be provisioned with plenty
+of extra space, if say, a 500 page file might be sent.
+
+To check temporary storage usage on actual files, run
+``ocrmypdf -k ...`` which will preserve and print the path to temporary
+storage when the job is done.
+
+To change where temporary files are stored, change the ``TMPDIR``
+environment variable for ocrmypdf's environment. (Python's
+``tempfile.gettempdir()`` returns the root directory in which temporary
+files will be stored.) For example, one could redirect ``TMPDIR`` to a
+large RAM disk to avoid wear on HDD/SSD and potentially improve
+performance. On Amazon Web Services, ``TMPDIR`` can be set to `empheral
+storage <https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/InstanceStorage.html>`__.
+
+Timeouts
+--------
+
+To prevent excessively long OCR jobs consider setting
+``--tesseract-timeout`` and/or ``--skip-big`` arguments. ``--skip-big``
+is particularly helpful if your PDFs include documents such as reports
+on standard page sizes with large images attached - often large images
+are not worth OCR'ing anyway.
+
+Commercial alternatives
+-----------------------
+
+The author also provides professional services that include OCR and
+building databases around PDFs, and is happy to provide consultation.
+
+Abbyy Cloud OCR is viable commercial alternative with a web services
+API. Amazon Textract, Google Cloud Vision, and Microsoft Azure 
+Computer Vision provide advanced OCR but have less PDF rendering capability.
+
+Password protection, digital signatures and certification
+=========================================================
+
+Password protected PDFs usually have two passwords, and owner and user
+password. When the user password is set to empty, PDF readers will open
+the file automatically and marked it as "(SECURED)". While not as
+reliable as a digital signature, this indicates that whoever set the
+password approved of the file at that time. When the user password is
+set, the document cannot be viewed without the password.
+
+Either way, OCRmyPDF does not remove passwords from PDFs and exits with
+an error on encountering them.
+
+``qpdf`` can remove passwords. If the owner and user password are set, a
+password is required for ``qpdf``. If only the owner password is set, then the
+password can be stripped, even if one does not have the owner password.
+
+After OCR is applied, password protection is not permitted on PDF/A
+documents but the file can be converted to regular PDF.
+
+Many programs exist which are capable of inserting an image of someone's
+signature. On its own, this offers no security guarantees. It is trivial
+to remove the signature image and apply it to other files. This practice
+offers no real security.
+
+Important documents can be digitally signed and certified to attest to
+their authorship. OCRmyPDF cannot do this. Open source tools such as
+pdfbox (Java) have this capability as does Adobe Acrobat.

docs/performance.rst

@@ -0,0 +1,22 @@
+===========
+Performance
+===========
+
+Some users have noticed that current versions of OCRmyPDF do not run as quickly
+as some older versions (specifically 6.x and older). This is because OCRmyPDF
+added image optimization as a postprocessing step, and it is enabled by default.
+
+Speed
+=====
+
+If running OCRmyPDF quickly is your main goal, you can use settings such as:
+
+* ``--optimize 0`` to disable file size optimization
+* ``--output-type pdf`` to disable PDF/A generation
+* ``--fast-web-view 0`` to disable fast web view optimization
+* ``--skip-big`` to skip large images, if some pages have large images
+
+You can also avoid:
+
+* ``--force-ocr``
+* Image preprocessing

docs/plugins.rst

@@ -0,0 +1,208 @@
+=======
+Plugins
+=======
+
+    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
+    NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and
+    "OPTIONAL" in this document are to be interpreted as described in
+    RFC 2119.
+
+You can use plugins to customize the behavior of OCRmyPDF at certain points of
+interest.
+
+Currently, it is possible to:
+
+- add new command line arguments
+- override the decision for whether or not to perform OCR on a particular file
+- modify the image is about to be sent for OCR
+- modify the page image before it is converted to PDF
+- replace the Tesseract OCR with another OCR engine that has similar behavior
+- replace Ghostscript with another PDF to image converter (rasterizer) or
+  PDF/A generator
+
+OCRmyPDF plugins are based on the Python ``pluggy`` package and conform to its
+conventions. Note that: plugins installed with as setuptools entrypoints are
+not checked currently, because OCRmyPDF assumes you may not want to enable
+plugins for all files.
+
+Script plugins
+==============
+
+Script plugins may be called from the command line, by specifying the name of a file.
+Script plugins may be convenient for informal or "one-off" plugins, when a certain
+batch of files needs a special processing step for example.
+
+.. code-block:: bash
+
+    ocrmypdf --plugin ocrmypdf_example_plugin.py input.pdf output.pdf
+
+Multiple plugins may be installed by issuing the ``--plugin`` argument multiple times.
+
+Packaged plugins
+================
+
+Installed plugins may be installed into the same virtual environment as OCRmyPDF
+is installed into. They may be invoked using Python standard module naming.
+If you are intending to distribute a plugin, please package it.
+
+.. code-block:: bash
+
+    ocrmypdf --plugin ocrmypdf_fancypants.pockets.contents input.pdf output.pdf
+
+OCRmyPDF does not automatically import plugins, because the assumption is that
+plugins affect different files differently and you may not want them activated
+all the time. The command line or ``ocrmypdf.ocr(plugin='...')`` must call
+for them.
+
+Third parties that wish to distribute packages for ocrmypdf should package them
+as packaged plugins, and these modules should begin with the name ``ocrmypdf_``
+similar to ``pytest`` packages such as ``pytest-cov`` (the package) and
+``pytest_cov`` (the module).
+
+.. note::
+
+    We recommend plugin authors name their plugins with the prefix
+    ``ocrmypdf-`` (for the package name on PyPI) and ``ocrmypdf_`` (for the
+    module), just like pytest plugins. At the same time, please make it clear
+    that your package is not official.
+
+Setuptools plugins
+==================
+
+You can also create a plugin that OCRmyPDF will always automatically load if both are
+installed in the same virtual environment, using a setuptools entrypoint.
+
+Your package's ``setup.py`` would need to contain the following, for a plugin
+named ``ocrmypdf-exampleplugin``:
+
+.. code-block:: python
+
+    # sample ./setup.py file
+    from setuptools import setup
+
+    setup(
+        name="ocrmypdf-exampleplugin",
+        packages=["exampleplugin"],
+        # the following makes a plugin available to pytest
+        entry_points={"ocrmypdf": ["exampleplugin = exampleplugin.pluginmodule"]},
+    )
+
+.. code-block:: ini
+
+    # equivalent setup.cfg
+    [options.entry_points]
+    ocrmypdf =
+        exampleplugin = exampleplugin.pluginmodule
+
+Plugin requirements
+===================
+
+OCRmyPDF generally uses multiple worker processes. When a new worker is started,
+Python will import all plugins again, including all plugins that were imported earlier.
+This means that the global state of a plugin in one worker will not be shared with
+other workers. As such, plugin hook implementations should be stateless, relying
+only on their inputs. Hook implementations may use their input parameters to
+to obtain a reference to shared state prepared by another hook implementation.
+Plugins must expect that other instances of the plugin will be running
+simultaneously.
+
+The ``context`` object that is passed to many hooks can be used to share information
+about a file being worked on. Plugins must write private, plugin-specific data to
+a subfolder named ``{options.work_folder}/ocrmypdf-plugin-name``. Plugins MAY
+read and write files in ``options.work_folder``, but should be aware that their
+semantics are subject to change.
+
+OCRmyPDF will delete ``options.work_folder`` when it has finished OCRing
+a file, unless invoked with ``--keep-temporary-files``.
+
+The documentation for some plugin hooks contain a detailed description of the
+execution context in which they will be called.
+
+Plugins should be prepared to work whether executed in worker threads or worker
+processes. Generally, OCRmyPDF uses processes, but has a semi-hidden threaded
+argument that simplifies debugging.
+
+
+Plugin hooks
+============
+
+A plugin may provide the following hooks. Hooks must be decorated with
+``ocrmypdf.hookimpl``, for example:
+
+.. code-block:: python
+
+    from ocrmpydf import hookimpl
+
+    @hookimpl
+    def add_options(parser):
+        pass
+
+The following is a complete list of hooks that are available, and when
+they are called.
+
+.. _firstresult:
+
+**Note on firstresult hooks**
+
+If multiple plugins install implementations for this hook, they will be called in
+the reverse of the order in which they are installed (i.e., last plugin wins).
+When each hook implementation is called in order, the first implementation that
+returns a value other than ``None`` will "win" and prevent execution of all other
+hooks. As such, you cannot "chain" a series of plugin filters together in this
+way. Instead, a single hook implementation should be responsible for any such
+chaining operations.
+
+Custom command line arguments
+-----------------------------
+
+.. autofunction:: ocrmypdf.pluginspec.add_options
+
+.. autofunction:: ocrmypdf.pluginspec.check_options
+
+Execution and progress reporting
+--------------------------------
+
+.. autoclass: ocrmypdf.pluginspec.Executor
+    :members:
+
+.. autofunction:: ocrmypdf.pluginspec.get_logging_console
+
+.. autofunction:: ocrmypdf.pluginspec.get_executor
+
+.. autofunction:: ocrmypdf.pluginspec.get_progressbar_class
+
+Applying special behavior before processing
+-------------------------------------------
+
+.. autofunction:: ocrmypdf.pluginspec.validate
+
+PDF page to image
+-----------------
+
+.. autofunction:: ocrmypdf.pluginspec.rasterize_pdf_page
+
+Modifying intermediate images
+-----------------------------
+
+.. autofunction:: ocrmypdf.pluginspec.filter_ocr_image
+
+.. autofunction:: ocrmypdf.pluginspec.filter_page_image
+
+.. autofunction:: ocrmypdf.pluginspec.filter_pdf_page
+
+OCR engine
+----------
+
+.. autofunction:: ocrmypdf.pluginspec.get_ocr_engine
+
+.. autoclass:: ocrmypdf.pluginspec.OcrEngine
+    :members:
+
+    .. automethod:: __str__
+
+.. autoclass:: ocrmypdf.pluginspec.OrientationConfidence
+
+PDF/A production
+----------------
+
+.. autofunction:: ocrmypdf.pluginspec.generate_pdfa

misc/batch.py

@@ -0,0 +1,62 @@
+#!/usr/bin/env python3
+# Copyright 2016 findingorder: https://github.com/findingorder
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+# This script must be edited to meet your needs.
+
+import logging
+import os
+import sys
+from pathlib import Path
+
+import ocrmypdf
+
+# pylint: disable=logging-format-interpolation
+# pylint: disable=logging-not-lazy
+
+script_dir = Path(__file__).parent
+
+if len(sys.argv) > 1:
+    start_dir = Path(sys.argv[1])
+else:
+    start_dir = Path('.')
+
+if len(sys.argv) > 2:
+    log_file = Path(sys.argv[2])
+else:
+    log_file = script_dir.with_name('ocr-tree.log')
+
+logging.basicConfig(
+    level=logging.INFO,
+    format='%(asctime)s %(message)s',
+    filename=log_file,
+    filemode='a',
+)
+
+ocrmypdf.configure_logging(ocrmypdf.Verbosity.default)
+
+for filename in start_dir.glob("**/*.py"):
+    logging.info(f"Processing {filename}")
+    result = ocrmypdf.ocr(filename, filename, deskew=True)
+    if result == ocrmypdf.ExitCode.already_done_ocr:
+        logging.error("Skipped document because it already contained text")
+    elif result == ocrmypdf.ExitCode.ok:
+        logging.info("OCR complete")
+    logging.info(result)

misc/completion/ocrmypdf.bash

@@ -0,0 +1,120 @@
+# ocrmypdf completion                                     -*- shell-script -*-
+
+# Copyright 2019 Frank Pille
+# Copyright 2020 Alex Willner
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+set -o errexit
+
+_ocrmypdf()
+{
+    local cur prev cword words split
+
+    # Homebrew on Macs have version 1.3 of bash-completion which doesn't include - see #502
+    if declare -F _init_completions >/dev/null 2>&1; then
+        _init_completion -s || return
+    else
+        COMPREPLY=()
+        _get_comp_words_by_ref cur prev words cword
+    fi
+
+    if [[ $cur == -* ]]; then
+        COMPREPLY=( $( compgen -W '--language --image-dpi --output-type
+            --sidecar --version --jobs --quiet --verbose --title --author
+            --subject --keywords --rotate-pages --deskew
+            --clean --clean-final --unpaper-args --oversample --remove-vectors
+            --force-ocr --skip-text --redo-ocr
+            --skip-big --jpeg-quality --png-quality --jbig2-lossy
+            --max-image-mpixels --tesseract-config --tesseract-pagesegmode
+            --help --tesseract-oem --pdf-renderer --tesseract-timeout
+            --rotate-pages-threshold --pdfa-image-compression --user-words
+            --user-patterns --keep-temporary-files --output-type
+            --no-progress-bar --pages --fast-web-view' \
+            --  "$cur" ) )
+        return
+    else
+        _filedir
+        return
+    fi
+
+    case $prev in
+        --version|-h|--help)
+            return
+            ;;
+        --user-words|--user-patterns|--tesseract-config)
+            _filedir
+            return
+            ;;
+        --output-type)
+            COMPREPLY=( $( compgen -W 'pdfa pdf pdfa-1 pdfa-2 pdfa-3' -- \
+                "$cur" ) )
+            return
+            ;;
+        --pdf-renderer)
+            COMPREPLY=( $( compgen -W 'auto hocr sandwich' -- "$cur" ) )
+            return
+            ;;
+        --pdfa-image-compression)
+            COMPREPLY=( $( compgen -W 'auto jpeg lossless' -- "$cur" ) )
+            return
+            ;;
+        -O|--optimize|--tesseract-oem)
+            COMPREPLY=( $( compgen -W '{0..3}' -- "$cur" ) )
+            return
+            ;;
+        --jpeg-quality|--png-quality)
+            COMPREPLY=( $( compgen -W '{0..100}' -- "$cur" ) )
+            return
+            ;;
+        -l|--language)
+            COMPREPLY=$( command tesseract --list-langs 2>/dev/null )
+            COMPREPLY=( $( compgen -W '${COMPREPLY[@]##*:}' -- "$cur" ) )
+            return
+            ;;
+        --image-dpi|--oversample|--skip-big|--max-image-mpixels|\
+        --tesseract-timeout|--rotate-pages-threshold)
+            COMPREPLY=( $( compgen -P "$cur" -W '{0..9}' ) )
+            return
+            ;;
+        -j|--jobs)
+            COMPREPLY=( $( compgen -W '{1..'$( _ncpus )'}' -- "$cur" ) )
+            return
+            ;;
+        -v|--verbose)
+            COMPREPLY=( $( compgen -W '{0..2}' -- "$cur" ) ) # max level ?
+            return
+            ;;
+        --tesseract-pagesegmode)
+            COMPREPLY=( $( compgen -W '{1..13}' -- "$cur" ) )
+            return
+            ;;
+        --sidecar|--title|--author|--subject|--keywords|--unpaper-args|--pages|--fast-web-view)
+            # argument required but no completions available
+            return
+            ;;
+    esac
+
+    $split && return
+} &&
+complete -F _ocrmypdf ocrmypdf
+
+set +o errexit
+
+# ex: filetype=sh

misc/completion/ocrmypdf.fish

@@ -0,0 +1,139 @@
+# Copyright 2020 James R. Barlow
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+complete -c ocrmypdf -x -n '__fish_is_first_arg' -l version
+complete -c ocrmypdf -x -n '__fish_is_first_arg' -s h -s "?" -l help
+
+complete -c ocrmypdf -r -l sidecar -d "write OCR to text file"
+complete -c ocrmypdf -x -s q -l quiet
+
+complete -c ocrmypdf -s r -l rotate-pages -d "rotate pages to correct orientation"
+complete -c ocrmypdf -s d -l deskew -d "fix small horizontal alignment skew"
+complete -c ocrmypdf -s c -l clean -d "clean document images before OCR"
+complete -c ocrmypdf -s i -l clean-final -d "clean document images and keep result"
+complete -c ocrmypdf -l remove-vectors -d "don't send vector objects to OCR"
+
+complete -c ocrmypdf -s f -l force-ocr -d "OCR documents that already have printable text"
+complete -c ocrmypdf -s s -l skip-ocr -d "skip OCR on pages that text, otherwise try OCR"
+complete -c ocrmypdf -l redo-ocr -d "redo OCR on any pages that seem to have OCR already"
+
+complete -c ocrmypdf -s k -l keep-temporary-files -d "keep temporary files (debug)"
+
+function __fish_ocrmypdf_languages
+    set langs (tesseract --list-langs ^/dev/null)
+    set arr (string split '\n' $langs)
+    for lang in $arr[2..-1]
+        echo $lang
+    end
+end
+complete -c ocrmypdf -x -s l -l language -a '(__fish_ocrmypdf_languages)' -d "language"
+
+complete -c ocrmypdf -x -l image-dpi -d "assume this DPI if input image DPI is unknown"
+
+function __fish_ocrmypdf_output_type
+    echo -e "pdfa\t"(_ "output a PDF/A (default)")
+    echo -e "pdf\t"(_ "output a standard PDF")
+    echo -e "pdfa-1\t"(_ "output a PDF/A-1b")
+    echo -e "pdfa-2\t"(_ "output a PDF/A-2b")
+    echo -e "pdfa-3\t"(_ "output a PDF/A-3b")
+    echo -e "none\t"(_ "do not produce an output PDF (for example, if you only care about --sidecar)")
+end
+complete -c ocrmypdf -x -l output-type -a '(__fish_ocrmypdf_output_type)' -d "select PDF output options"
+
+function __fish_ocrmypdf_pdf_renderer
+    echo -e "auto\t"(_ "auto select PDF renderer")
+    echo -e "hocr\t"(_ "use hOCR renderer")
+    echo -e "hocrdebug\t"(_ "uses hOCR renderer in debug mode, showing recognized text")
+    echo -e "sandwich\t"(_ "use sandwich renderer")
+end
+complete -c ocrmypdf -x -l pdf-renderer -a '(__fish_ocrmypdf_pdf_renderer)' -d "select PDF renderer options"
+
+function __fish_ocrmypdf_optimize
+    echo -e "0\t"(_ "do not optimize")
+    echo -e "1\t"(_ "do safe, lossless optimizations (default)")
+    echo -e "2\t"(_ "do some lossy optimizations")
+    echo -e "3\t"(_ "do aggressive lossy optimizations (including lossy JBIG2)")
+end
+complete -c ocrmypdf -x -s O -l optimize -a '(__fish_ocrmypdf_optimize)' -d "select optimization level"
+
+function __fish_ocrmypdf_verbose
+    echo -e "0\t"(_ "standard output messages")
+    echo -e "1\t"(_ "troubleshooting output messages")
+    echo -e "2\t"(_ "debugging output messages")
+end
+complete -c ocrmypdf -x -s v -l verbose -a '(__fish_ocrmypdf_verbose)' -d "set verbosity level"
+
+complete -c ocrmypdf -x -l no-progress-bar -d "disable the progress bar"
+
+function __fish_ocrmypdf_pdfa_compression
+    echo -e "auto\t"(_ "let Ghostscript decide how to compress images")
+    echo -e "jpeg\t"(_ "convert color and grayscale images to JPEG")
+    echo -e "lossless\t"(_ "convert color and grayscale images to lossless (PNG)")
+end
+complete -c ocrmypdf -x -l pdfa-image-compression -a '(__fish_ocrmypdf_pdfa_compression)' -d "set PDF/A image compression options"
+
+complete -c ocrmypdf -x -s j -l jobs -d "how many worker processes to use"
+complete -c ocrmypdf -x -l title -d "set metadata"
+complete -c ocrmypdf -x -l author -d "set metadata"
+complete -c ocrmypdf -x -l subject -d "set metadata"
+complete -c ocrmypdf -x -l keywords -d "set metadata"
+complete -c ocrmypdf -x -l oversample -d "oversample images to this DPI"
+complete -c ocrmypdf -x -l skip-big -d "skip OCR on pages larger than this many MPixels"
+
+complete -c ocrmypdf -x -l jpeg-quality -d "JPEG quality [0..100]"
+complete -c ocrmypdf -x -l png-quality -d "PNG quality [0..100]"
+complete -c ocrmypdf -x -l jbig2-lossy -d "enable lossy JBIG2 (see docs)"
+complete -c ocrmypdf -x -l max-image-mpixels -d "image decompression bomb threshold"
+complete -c ocrmypdf -x -l pages -d "apply OCR to only the specified pages"
+complete -c ocrmypdf -x -l tesseract-config -d "set custom tesseract config file"
+
+function __fish_ocrmypdf_tesseract_pagesegmode
+  echo -e "0\t"(_ "orientation and script detection (OSD) only")
+  echo -e "1\t"(_ "automatic page segmentation with OSD")
+  echo -e "2\t"(_ "automatic page segmentation, but no OSD, or OCR")
+  echo -e "3\t"(_ "fully automatic page segmentation, but no OSD (default)")
+  echo -e "4\t"(_ "assume a single column of text of variable sizes")
+  echo -e "5\t"(_ "assume a single uniform block of vertically aligned text")
+  echo -e "6\t"(_ "assume a single uniform block of text")
+  echo -e "7\t"(_ "treat the image as a single text line")
+  echo -e "8\t"(_ "treat the image as a single word")
+  echo -e "9\t"(_ "treat the image as a single word in a circle")
+  echo -e "10\t"(_ "treat the image as a single character")
+  echo -e "11\t"(_ "sparse text - find as much text as possible in no particular order")
+  echo -e "12\t"(_ "sparse text with OSD")
+  echo -e "13\t"(_ "raw line - treat the image as a single text line")
+end
+complete -c ocrmypdf -x -l tesseract-pagesegmode -a '(__fish_ocrmypdf_tesseract_pagesegmode)' -d "set tesseract --psm"
+
+function __fish_ocrmypdf_tesseract_oem
+    echo -e "0\t"(_ "legacy engine only")
+    echo -e "1\t"(_ "neural nets LSTM engine only")
+    echo -e "2\t"(_ "legacy + LSTM engines")
+    echo -e "3\t"(_ "default, based on what is available")
+end
+complete -c ocrmypdf -x -l tesseract-oem -a '(__fish_ocrmypdf_tesseract_oem)' -d "set tesseract --oem"
+complete -c ocrmypdf -x -l tesseract-timeout -d "maximum number of seconds to wait for OCR"
+complete -c ocrmypdf -x -l rotate-pages-threshold -d "page rotation confidence"
+
+complete -c ocrmypdf -r -l user-words -d "specify location of user words file"
+complete -c ocrmypdf -r -l user-patterns -d "specify location of user patterns file"
+complete -c ocrmypdf -x -l fast-web-view -d "if file size if above this amount in MB, linearize PDF"
+
+complete -c ocrmypdf -x -a "(__fish_complete_suffix .pdf; __fish_complete_suffix .PDF; __fish_complete_suffix .jpg; __fish_complete_suffix .png)"

misc/docker-compose.example.yml

@@ -0,0 +1,15 @@
+---
+version: "3.3"
+services:
+  ocrmypdf:
+    restart: always
+    container_name: ocrmypdf
+    image: jbarlow83/ocrmypdf
+    volumes:
+      - "/media/scan:/input"
+      - "/mnt/scan:/output"
+    environment:
+      - OCR_OUTPUT_DIRECTORY_YEAR_MONTH=0
+    user: "<SET TO YOUR USER ID>:<SET TO YOUR GROUP ID>"
+    entrypoint: python3
+    command: watcher.py

misc/example_plugin.py

@@ -0,0 +1,84 @@
+# © 2020 James R Barlow: https://github.com/jbarlow83
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+"""
+An example of an OCRmyPDF plugin.
+
+This plugin adds two new command line arguments
+    --grayscale-ocr: converts the image to grayscale before performing OCR on it
+        (This is occasionally useful for images whose color confounds OCR. It only
+        affects the image shown to OCR. The image is not saved.)
+    --mono-page: converts pages all pages in the output file to black and white
+
+To use this from the command line:
+    ocrmypdf --plugin path/to/example_plugin.py --mono-page input.pdf output.pdf
+
+To use this as an API:
+    import ocrmypdf
+    ocrmypdf.ocr('input.pdf', 'output.pdf',
+        plugins=['path/to/example_plugin.py'], mono_page=True
+    )
+"""
+
+import logging
+
+from PIL import Image
+
+from ocrmypdf import hookimpl
+
+log = logging.getLogger(__name__)
+
+
+@hookimpl
+def add_options(parser):
+    parser.add_argument('--grayscale-ocr', action='store_true')
+    parser.add_argument('--mono-page', action='store_true')
+
+
+@hookimpl
+def prepare(options):
+    pass
+
+
+@hookimpl
+def validate(pdfinfo, options):
+    pass
+
+
+@hookimpl
+def filter_ocr_image(page, image):
+    if page.options.grayscale_ocr:
+        log.info("graying")
+        return image.convert('L')
+    return image
+
+
+@hookimpl
+def filter_page_image(page, image_filename):
+    if page.options.mono_page:
+        with Image.open(image_filename) as im:
+            im = im.convert('1')
+            im.save(image_filename)
+        return image_filename
+    else:
+        output = image_filename.with_suffix('.jpg')
+        with Image.open(image_filename) as im:
+            im.save(output)
+        return output

misc/synology.py

@@ -0,0 +1,92 @@
+#!/bin/env python3
+# Copyright 2017 github.com/Enantiomerie
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+# This script must be edited to meet your needs.
+
+import logging
+import os
+import shutil
+import subprocess
+import sys
+import time
+
+# pylint: disable=logging-format-interpolation
+# pylint: disable=logging-not-lazy
+
+script_dir = os.path.dirname(os.path.realpath(__file__))
+timestamp = time.strftime("%Y-%m-%d-%H%M_")
+log_file = script_dir + '/' + timestamp + 'ocrmypdf.log'
+logging.basicConfig(
+    level=logging.INFO,
+    format='%(asctime)s %(message)s',
+    filename=log_file,
+    filemode='w',
+)
+
+if len(sys.argv) > 1:
+    start_dir = sys.argv[1]
+else:
+    start_dir = '.'
+
+for dir_name, _subdirs, file_list in os.walk(start_dir):
+    logging.info(dir_name)
+    os.chdir(dir_name)
+    for filename in file_list:
+        file_stem, file_ext = os.path.splitext(filename)
+        if file_ext != '.pdf':
+            continue
+        full_path = os.path.join(dir_name, filename)
+        timestamp_ocr = time.strftime("%Y-%m-%d-%H%M_OCR_")
+        filename_ocr = timestamp_ocr + file_stem + '.pdf'
+        # create string for pdf processing
+        # the script is processed as root user via chron
+        cmd = [
+            'docker',
+            'run',
+            '--rm',
+            '-i',
+            'jbarlow83/ocrmypdf',
+            '--deskew',
+            '-',
+            '-',
+        ]
+        logging.info(cmd)
+        full_path_ocr = os.path.join(dir_name, filename_ocr)
+        with open(filename, 'rb') as input_file, open(
+            full_path_ocr, 'wb'
+        ) as output_file:
+            proc = subprocess.run(
+                cmd,
+                stdin=input_file,
+                stdout=output_file,
+                stderr=subprocess.PIPE,
+                check=False,
+                text=True,
+                errors='ignore',
+            )
+        logging.info(proc.stderr)
+        os.chmod(full_path_ocr, 0o664)
+        os.chmod(full_path, 0o664)
+        full_path_ocr_archive = sys.argv[2]
+        full_path_archive = sys.argv[2] + '/no_ocr'
+        shutil.move(full_path_ocr, full_path_ocr_archive)
+        shutil.move(full_path, full_path_archive)
+logging.info('Finished.\n')

misc/watcher.py

@@ -0,0 +1,172 @@
+#!/usr/bin/env python3
+# Copyright (C) 2019 Ian Alexander: https://github.com/ianalexander
+# Copyright (C) 2020 James R Barlow: https://github.com/jbarlow83
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+import json
+import logging
+import os
+import sys
+import time
+from datetime import datetime
+from pathlib import Path
+
+import pikepdf
+from watchdog.events import PatternMatchingEventHandler
+from watchdog.observers import Observer
+from watchdog.observers.polling import PollingObserver
+
+import ocrmypdf
+
+# pylint: disable=logging-format-interpolation
+
+
+def getenv_bool(name: str, default: str = 'False'):
+    return os.getenv(name, default).lower() in ('true', 'yes', 'y', '1')
+
+
+INPUT_DIRECTORY = os.getenv('OCR_INPUT_DIRECTORY', '/input')
+OUTPUT_DIRECTORY = os.getenv('OCR_OUTPUT_DIRECTORY', '/output')
+OUTPUT_DIRECTORY_YEAR_MONTH = getenv_bool('OCR_OUTPUT_DIRECTORY_YEAR_MONTH')
+ON_SUCCESS_DELETE = getenv_bool('OCR_ON_SUCCESS_DELETE')
+DESKEW = getenv_bool('OCR_DESKEW')
+OCR_JSON_SETTINGS = json.loads(os.getenv('OCR_JSON_SETTINGS', '{}'))
+POLL_NEW_FILE_SECONDS = int(os.getenv('OCR_POLL_NEW_FILE_SECONDS', '1'))
+USE_POLLING = getenv_bool('OCR_USE_POLLING')
+LOGLEVEL = os.getenv('OCR_LOGLEVEL', 'INFO')
+PATTERNS = ['*.pdf', '*.PDF']
+
+log = logging.getLogger('ocrmypdf-watcher')
+
+
+def get_output_dir(root, basename):
+    if OUTPUT_DIRECTORY_YEAR_MONTH:
+        today = datetime.today()
+        output_directory_year_month = (
+            Path(root) / str(today.year) / f'{today.month:02d}'
+        )
+        if not output_directory_year_month.exists():
+            output_directory_year_month.mkdir(parents=True, exist_ok=True)
+        output_path = Path(output_directory_year_month) / basename
+    else:
+        output_path = Path(OUTPUT_DIRECTORY) / basename
+    return output_path
+
+
+def wait_for_file_ready(file_path):
+    # This loop waits to make sure that the file is completely loaded on
+    # disk before attempting to read. Docker sometimes will publish the
+    # watchdog event before the file is actually fully on disk, causing
+    # pikepdf to fail.
+
+    retries = 5
+    while retries:
+        try:
+            pdf = pikepdf.open(file_path)
+        except (FileNotFoundError, pikepdf.PdfError) as e:
+            log.info(f"File {file_path} is not ready yet")
+            log.debug("Exception was", exc_info=e)
+            time.sleep(POLL_NEW_FILE_SECONDS)
+            retries -= 1
+        else:
+            pdf.close()
+            return True
+
+    return False
+
+
+def execute_ocrmypdf(file_path):
+    file_path = Path(file_path)
+    output_path = get_output_dir(OUTPUT_DIRECTORY, file_path.name)
+
+    log.info("-" * 20)
+    log.info(f'New file: {file_path}. Waiting until fully loaded...')
+    if not wait_for_file_ready(file_path):
+        log.info(f"Gave up waiting for {file_path} to become ready")
+        return
+    log.info(f'Attempting to OCRmyPDF to: {output_path}')
+    exit_code = ocrmypdf.ocr(
+        input_file=file_path,
+        output_file=output_path,
+        deskew=DESKEW,
+        **OCR_JSON_SETTINGS,
+    )
+    if exit_code == 0 and ON_SUCCESS_DELETE:
+        log.info(f'OCR is done. Deleting: {file_path}')
+        file_path.unlink()
+    else:
+        log.info('OCR is done')
+
+
+class HandleObserverEvent(PatternMatchingEventHandler):
+    def on_any_event(self, event):
+        if event.event_type in ['created']:
+            execute_ocrmypdf(event.src_path)
+
+
+def main():
+    ocrmypdf.configure_logging(
+        verbosity=(
+            ocrmypdf.Verbosity.default
+            if LOGLEVEL != 'DEBUG'
+            else ocrmypdf.Verbosity.debug
+        ),
+        manage_root_logger=True,
+    )
+    log.setLevel(LOGLEVEL)
+    log.info(
+        f"Starting OCRmyPDF watcher with config:\n"
+        f"Input Directory: {INPUT_DIRECTORY}\n"
+        f"Output Directory: {OUTPUT_DIRECTORY}\n"
+        f"Output Directory Year & Month: {OUTPUT_DIRECTORY_YEAR_MONTH}"
+    )
+    log.debug(
+        f"INPUT_DIRECTORY: {INPUT_DIRECTORY}\n"
+        f"OUTPUT_DIRECTORY: {OUTPUT_DIRECTORY}\n"
+        f"OUTPUT_DIRECTORY_YEAR_MONTH: {OUTPUT_DIRECTORY_YEAR_MONTH}\n"
+        f"ON_SUCCESS_DELETE: {ON_SUCCESS_DELETE}\n"
+        f"DESKEW: {DESKEW}\n"
+        f"ARGS: {OCR_JSON_SETTINGS}\n"
+        f"POLL_NEW_FILE_SECONDS: {POLL_NEW_FILE_SECONDS}\n"
+        f"USE_POLLING: {USE_POLLING}\n"
+        f"LOGLEVEL: {LOGLEVEL}"
+    )
+
+    if 'input_file' in OCR_JSON_SETTINGS or 'output_file' in OCR_JSON_SETTINGS:
+        log.error('OCR_JSON_SETTINGS should not specify input file or output file')
+        sys.exit(1)
+
+    handler = HandleObserverEvent(patterns=PATTERNS)
+    if USE_POLLING:
+        observer = PollingObserver()
+    else:
+        observer = Observer()
+    observer.schedule(handler, INPUT_DIRECTORY, recursive=True)
+    observer.start()
+    try:
+        while True:
+            time.sleep(1)
+    except KeyboardInterrupt:
+        observer.stop()
+    observer.join()
+
+
+if __name__ == "__main__":
+    main()

misc/webservice.py

@@ -0,0 +1,118 @@
+#!/usr/bin/env python3
+# webservice.py wrapper for OCRmyPDF
+# Copyright (C) 2019 James R. Barlow: github.com/jbarlow83
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+"""This is a simple web service/HTTP wrapper for OCRmyPDF
+
+This may be more convenient than the command line tool for some Docker users.
+Note that OCRmyPDF uses Ghostscript, which is licensed under AGPLv3+. While
+OCRmyPDF is under GPLv3, this file is distributed under the Affero GPLv3+ license,
+to emphasize that SaaS deployments should make sure they comply with
+Ghostscript's license as well as OCRmyPDF's.
+"""
+
+import os
+import shlex
+from subprocess import PIPE, run
+from tempfile import TemporaryDirectory
+
+from flask import Flask, Response, request, send_from_directory
+from werkzeug.utils import secure_filename
+
+app = Flask(__name__)
+app.secret_key = "secret"
+app.config['MAX_CONTENT_LENGTH'] = 50_000_000
+app.config.from_envvar("OCRMYPDF_WEBSERVICE_SETTINGS", silent=True)
+
+ALLOWED_EXTENSIONS = {"pdf"}
+
+
+def allowed_file(filename):
+    return "." in filename and filename.rsplit(".", 1)[1].lower() in ALLOWED_EXTENSIONS
+
+
+def do_ocrmypdf(file):
+    uploaddir = TemporaryDirectory(prefix="ocrmypdf-upload")
+    downloaddir = TemporaryDirectory(prefix="ocrmypdf-download")
+
+    filename = secure_filename(file.filename)
+    up_file = os.path.join(uploaddir.name, filename)
+    file.save(up_file)
+
+    down_file = os.path.join(downloaddir.name, filename)
+
+    cmd_args = [arg for arg in shlex.split(request.form["params"])]
+    if "--sidecar" in cmd_args:
+        return Response("--sidecar not supported", 501, mimetype='text/plain')
+
+    ocrmypdf_args = ["ocrmypdf", *cmd_args, up_file, down_file]
+    proc = run(ocrmypdf_args, stdout=PIPE, stderr=PIPE, encoding="utf-8")
+    if proc.returncode != 0:
+        stderr = proc.stderr
+        return Response(stderr, 400, mimetype='text/plain')
+
+    return send_from_directory(downloaddir.name, filename)
+
+
+@app.route("/", methods=["GET", "POST"])
+def upload_file():
+    if request.method == "POST":
+        if "file" not in request.files:
+            return Response("No file in POST", 400, mimetype='text/plain')
+        file = request.files["file"]
+        if file.filename == "":
+            return Response("Empty filename", 400, mimetype='text/plain')
+        if not allowed_file(file.filename):
+            return Response("Invalid filename", 400, mimetype='text/plain')
+        if file and allowed_file(file.filename):
+            return do_ocrmypdf(file)
+        return Response("Some other problem", 400, mimetype='text/plain')
+
+    return """
+    <!doctype html>
+    <title>OCRmyPDF webservice</title>
+    <h1>Upload a PDF (debug UI)</h1>
+    <form method=post enctype=multipart/form-data>
+      <label for="args">Command line parameters</label>
+      <input type=textbox name=params>
+      <label for="file">File to upload</label>
+      <input type=file name=file>
+      <input type=submit value=Upload>
+    </form>
+    <h4>Notice</h2>
+    <div style="font-size: 70%; max-width: 34em;">
+    <p>This is a webservice wrapper for OCRmyPDF.</p>
+    <p>Copyright 2019 James R. Barlow</p>
+    <p>This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Affero General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+    </p>
+    <p>This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+    </p>
+    <p>
+    You should have received a copy of the GNU Affero General Public License
+    along with this program.  If not, see &lt;http://www.gnu.org/licenses/&gt;.
+    </p>
+    </div>
+    """
+
+
+if __name__ == "__main__":
+    app.run(host='0.0.0.0', port=5000)

ocrmypdf/__init__.py

@@ -1,12 +0,0 @@
-from enum import IntEnum
-
-
-class ExitCode(IntEnum):
-    ok = 0
-    bad_args = 1
-    input_file = 2
-    missing_dependency = 3
-    invalid_output_pdfa = 4
-    file_access_error = 5
-    already_done_ocr = 6
-    other_error = 15

ocrmypdf/ghostscript.py

@@ -1,52 +0,0 @@
-#!/usr/bin/env python3
-# © 2015 James R. Barlow: github.com/jbarlow83
-
-from tempfile import NamedTemporaryFile
-from subprocess import Popen, PIPE, check_call
-from shutil import copy
-
-
-def rasterize_pdf(input_file, output_file, xres, yres, raster_device, log):
-    with NamedTemporaryFile(delete=True) as tmp:
-        args_gs = [
-            'gs',
-            '-dBATCH', '-dNOPAUSE',
-            '-sDEVICE=%s' % raster_device,
-            '-o', tmp.name,
-            '-r{0}x{1}'.format(str(xres), str(yres)),
-            input_file
-        ]
-
-        p = Popen(args_gs, close_fds=True, stdout=PIPE, stderr=PIPE,
-                  universal_newlines=True)
-        stdout, stderr = p.communicate()
-        if stdout:
-            log.debug(stdout)
-        if stderr:
-            log.error(stderr)
-
-        if p.returncode == 0:
-            copy(tmp.name, output_file)
-        else:
-            log.error('Ghostscript rendering failed')
-
-
-def generate_pdfa(pdf_pages, output_file, threads=1):
-    with NamedTemporaryFile(delete=True) as gs_pdf:
-        args_gs = [
-            "gs",
-            "-dQUIET",
-            "-dBATCH",
-            "-dNOPAUSE",
-            '-dNumRenderingThreads=' + str(threads),
-            "-sDEVICE=pdfwrite",
-            "-sColorConversionStrategy=/RGB",
-            "-sProcessColorModel=DeviceRGB",
-            "-dPDFA",
-            "-sPDFACompatibilityPolicy=2",
-            "-sOutputICCProfile=srgb.icc",
-            "-sOutputFile=" + gs_pdf.name,
-        ]
-        args_gs.extend(pdf_pages)
-        check_call(args_gs)
-        copy(gs_pdf.name, output_file)

ocrmypdf/hocrtransform.py

@@ -1,231 +0,0 @@
-#!/usr/local/bin/python3
-##############################################################################
-# Copyright (c) 2013-14: fritz-hh from Github
-#   (https://github.com/fritz-hh)
-#
-# Copyright (c) 2010: Jonathan Brinley from Github
-#   (https://github.com/jbrinley/HocrConverter)
-#   Initial version by Jonathan Brinley, jonathanbrinley@gmail.com
-##############################################################################
-from reportlab.pdfgen.canvas import Canvas
-from reportlab.lib.units import inch
-from lxml import etree as ElementTree
-from PIL import Image
-from collections import namedtuple
-import re
-import argparse
-
-
-Rect = namedtuple('Rect', ['x1', 'y1', 'x2', 'y2'])
-
-
-class HocrTransformError(Exception):
-    pass
-
-
-class HocrTransform():
-
-    """
-    A class for converting documents from the hOCR format.
-    For details of the hOCR format, see:
-    http://docs.google.com/View?docid=dfxcv4vc_67g844kf
-    """
-
-    def __init__(self, hocrFileName, dpi):
-        self.dpi = dpi
-        self.boxPattern = re.compile(r'bbox((\s+\d+){4})')
-
-        self.hocr = ElementTree.ElementTree()
-        self.hocr.parse(hocrFileName)
-
-        # if the hOCR file has a namespace, ElementTree requires its use to
-        # find elements
-        matches = re.match(r'({.*})html', self.hocr.getroot().tag)
-        self.xmlns = ''
-        if matches:
-            self.xmlns = matches.group(1)
-
-        # get dimension in pt (not pixel!!!!) of the OCRed image
-        self.width, self.height = None, None
-        for div in self.hocr.findall(
-                ".//%sdiv[@class='ocr_page']" % (self.xmlns)):
-            coords = self.element_coordinates(div)
-            pt_coords = self.pt_from_pixel(coords)
-            self.width = pt_coords.x2 - pt_coords.x1
-            self.height = pt_coords.y2 - pt_coords.y1
-            # there shouldn't be more than one, and if there is, we don't want
-            # it
-            break
-        if self.width is None or self.height is None:
-            raise HocrTransformError("hocr file is missing page dimensions")
-
-    def __str__(self):
-        """
-        Return the textual content of the HTML body
-        """
-        if self.hocr is None:
-            return ''
-        body = self.hocr.find(".//%sbody" % (self.xmlns))
-        if body:
-            return self._get_element_text(body)
-        else:
-            return ''
-
-    def _get_element_text(self, element):
-        """
-        Return the textual content of the element and its children
-        """
-        text = ''
-        if element.text is not None:
-            text += element.text
-        for child in element.getchildren():
-            text += self._get_element_text(child)
-        if element.tail is not None:
-            text += element.tail
-        return text
-
-    def element_coordinates(self, element):
-        """
-        Returns a tuple containing the coordinates of the bounding box around
-        an element
-        """
-        out = (0, 0, 0, 0)
-        if 'title' in element.attrib:
-            matches = self.boxPattern.search(element.attrib['title'])
-            if matches:
-                coords = matches.group(1).split()
-                out = Rect._make(int(coords[n]) for n in range(4))
-        return out
-
-    def pt_from_pixel(self, pxl):
-        """
-        Returns the quantity in PDF units (pt) given quantity in pixels
-        """
-        return Rect._make(
-            (c / self.dpi * inch) for c in pxl)
-
-    def replace_unsupported_chars(self, s):
-        """
-        Given an input string, returns the corresponding string that:
-        - is available in the helvetica facetype
-        - does not contain any ligature (to allow easy search in the PDF file)
-        """
-        # The 'u' before the character to replace indicates that it is a
-        # unicode character
-        s = s.replace(u"fl", "fl")
-        s = s.replace(u"fi", "fi")
-        return s
-
-    def to_pdf(self, outFileName, imageFileName=None, showBoundingboxes=False,
-               fontname="Helvetica", invisibleText=False):
-        """
-        Creates a PDF file with an image superimposed on top of the text.
-        Text is positioned according to the bounding box of the lines in
-        the hOCR file.
-        The image need not be identical to the image used to create the hOCR
-        file.
-        It can have a lower resolution, different color mode, etc.
-        """
-        # create the PDF file
-        # page size in points (1/72 in.)
-        pdf = Canvas(
-            outFileName, pagesize=(self.width, self.height), pageCompression=1)
-
-        # draw bounding box for each paragraph
-        # light blue for bounding box of paragraph
-        pdf.setStrokeColorRGB(0, 1, 1)
-        # light blue for bounding box of paragraph
-        pdf.setFillColorRGB(0, 1, 1)
-        pdf.setLineWidth(0)		# no line for bounding box
-        for elem in self.hocr.findall(
-                ".//%sp[@class='%s']" % (self.xmlns, "ocr_par")):
-
-            elemtxt = self._get_element_text(elem).rstrip()
-            if len(elemtxt) == 0:
-                continue
-
-            pxl_coords = self.element_coordinates(elem)
-            pt = self.pt_from_pixel(pxl_coords)
-
-            # draw the bbox border
-            if showBoundingboxes:
-                pdf.rect(
-                    pt.x1, self.height - pt.y2, pt.x2 - pt.x1, pt.y2 - pt.y1,
-                    fill=1)
-
-        # check if element with class 'ocrx_word' are available
-        # otherwise use 'ocr_line' as fallback
-        elemclass = "ocr_line"
-        if self.hocr.find(
-                ".//%sspan[@class='ocrx_word']" % (self.xmlns)) is not None:
-            elemclass = "ocrx_word"
-
-        # itterate all text elements
-        # light green for bounding box of word/line
-        pdf.setStrokeColorRGB(1, 0, 0)
-        pdf.setLineWidth(0.5)		# bounding box line width
-        pdf.setDash(6, 3)		# bounding box is dashed
-        pdf.setFillColorRGB(0, 0, 0)  # text in black
-        for elem in self.hocr.findall(
-                ".//%sspan[@class='%s']" % (self.xmlns, elemclass)):
-
-            elemtxt = self._get_element_text(elem).rstrip()
-
-            elemtxt = self.replace_unsupported_chars(elemtxt)
-
-            if len(elemtxt) == 0:
-                continue
-
-            pxl_coords = self.element_coordinates(elem)
-            pt = self.pt_from_pixel(pxl_coords)
-
-            # draw the bbox border
-            if showBoundingboxes:
-                pdf.rect(
-                    pt.x1, self.height - pt.y2, pt.x2 - pt.x1, pt.y2 - pt.y1,
-                    fill=0)
-
-            text = pdf.beginText()
-            fontsize = pt.y2 - pt.y1
-            text.setFont(fontname, fontsize)
-            if invisibleText:
-                text.setTextRenderMode(3)  # Invisible (indicates OCR text)
-
-            # set cursor to bottom left corner of bbox (adjust for dpi)
-            text.setTextOrigin(pt.x1, self.height - pt.y2)
-
-            # scale the width of the text to fill the width of the bbox
-            text.setHorizScale(
-                100 * (pt.x2 - pt.x1) / pdf.stringWidth(
-                    elemtxt, fontname, fontsize))
-
-            # write the text to the page
-            text.textLine(elemtxt)
-            pdf.drawText(text)
-
-        # put the image on the page, scaled to fill the page
-        if imageFileName is not None:
-            pdf.drawImage(imageFileName, 0, 0,
-                          width=self.width, height=self.height)
-
-        # finish up the page and save it
-        pdf.showPage()
-        pdf.save()
-
-
-if __name__ == "__main__":
-    parser = argparse.ArgumentParser(description='Convert hocr file to PDF')
-    parser.add_argument('-b', '--boundingboxes', action="store_true",
-                        default=False, help='Show bounding boxes borders')
-    parser.add_argument('-r', '--resolution', type=int,
-                        default=300,
-                        help='Resolution of the image that was OCRed')
-    parser.add_argument('-i', '--image', default=None,
-                        help='Path to the image to be placed above the text')
-    parser.add_argument('hocrfile', help='Path to the hocr file to be parsed')
-    parser.add_argument(
-        'outputfile', help='Path to the PDF file to be generated')
-    args = parser.parse_args()
-
-    hocr = HocrTransform(args.hocrfile, args.resolution)
-    hocr.to_pdf(args.outputfile, args.image, args.boundingboxes)

ocrmypdf/leptonica.py

@@ -1,331 +0,0 @@
-#!/usr/bin/env python2
-# -*- coding: utf-8 -*-
-#
-# © 2013-15: jbarlow83 from Github (https://github.com/jbarlow83)
-#
-#
-# Use Leptonica to detect find and remove page skew.  Leptonica uses the method
-# of differential square sums, which its author claim is faster and more robust
-# than the Hough transform used by ImageMagick.
-
-from __future__ import print_function, absolute_import, division
-import argparse
-import ctypes as C
-import sys
-import os
-import logging
-from tempfile import TemporaryFile
-
-logger = logging.getLogger(__name__)
-
-
-def stderr(*objs):
-    """Python 2/3 compatible print to stderr.
-    """
-    print("leptonica.py:", *objs, file=sys.stderr)
-
-
-from ctypes.util import find_library
-lept_lib = find_library('lept')
-if not lept_lib:
-    stderr("Could not find the Leptonica library")
-    sys.exit(3)
-try:
-    lept = C.cdll.LoadLibrary(lept_lib)
-except Exception:
-    stderr("Could not load the Leptonica library from %s", lept_lib)
-    sys.exit(3)
-
-
-class _PIXCOLORMAP(C.Structure):
-    """struct PixColormap from Leptonica src/pix.h
-    """
-
-    _fields_ = [
-        ("array", C.c_void_p),
-        ("depth", C.c_int32),
-        ("nalloc", C.c_int32),
-        ("n", C.c_int32)
-    ]
-
-
-class _PIX(C.Structure):
-    """struct Pix from Leptonica src/pix.h
-    """
-
-    _fields_ = [
-        ("w", C.c_uint32),
-        ("h", C.c_uint32),
-        ("d", C.c_uint32),
-        ("wpl", C.c_uint32),
-        ("refcount", C.c_uint32),
-        ("xres", C.c_int32),
-        ("yres", C.c_int32),
-        ("informat", C.c_int32),
-        ("text", C.POINTER(C.c_char)),
-        ("colormap", C.POINTER(_PIXCOLORMAP)),
-        ("data", C.POINTER(C.c_uint32))
-    ]
-
-
-PIX = C.POINTER(_PIX)
-
-lept.pixRead.argtypes = [C.c_char_p]
-lept.pixRead.restype = PIX
-lept.pixScale.argtypes = [PIX, C.c_float, C.c_float]
-lept.pixScale.restype = PIX
-lept.pixDeskew.argtypes = [PIX, C.c_int32]
-lept.pixDeskew.restype = PIX
-lept.pixFindSkew.argtypes = [PIX, C.POINTER(C.c_float), C.POINTER(C.c_float)]
-lept.pixFindSkew.restype = C.c_int32
-lept.pixWriteImpliedFormat.argtypes = [C.c_char_p, PIX, C.c_int32, C.c_int32]
-lept.pixWriteImpliedFormat.restype = C.c_int32
-lept.pixDestroy.argtypes = [C.POINTER(PIX)]
-lept.pixDestroy.restype = None
-lept.getLeptonicaVersion.argtypes = []
-lept.getLeptonicaVersion.restype = C.c_char_p
-
-
-class LeptonicaErrorTrap(object):
-    """Context manager to trap errors reported by Leptonica.
-
-    Leptonica's error return codes are unreliable to the point of being
-    almost useless.  It does, however, write errors to stderr provided that is
-    not disabled at its compile time.  Fortunately this is done using error
-    macros so it is very self-consistent.
-
-    This context manager redirects stderr to a temporary file which is then
-    read and parsed for error messages.  As a side benefit, debug messages
-    from Leptonica are also suppressed.
-
-    """
-    def __enter__(self):
-        self.tmpfile = TemporaryFile()
-
-        # Save the old stderr, and redirect stderr to temporary file
-        self.old_stderr_fileno = os.dup(sys.stderr.fileno())
-        os.dup2(self.tmpfile.fileno(), sys.stderr.fileno())
-        return
-
-    def __exit__(self, exc_type, exc_value, traceback):
-        # Restore old stderr
-        os.dup2(self.old_stderr_fileno, sys.stderr.fileno())
-
-        # Get data from tmpfile (in with block to ensure it is closed)
-        with self.tmpfile as tmpfile:
-            tmpfile.seek(0)  # Cursor will be at end, so move back to beginning
-            leptonica_output = tmpfile.read().decode(errors='replace')
-
-        # If there are Python errors, let them bubble up
-        if exc_type:
-            logger.warning(leptonica_output)
-            return False
-
-        # If there are Leptonica errors, wrap them in Python excpetions
-        if 'Error' in leptonica_output:
-            if 'image file not found' in leptonica_output:
-                raise FileNotFoundError()
-            if 'pixWrite: stream not opened' in leptonica_output:
-                raise LeptonicaIOError()
-            raise LeptonicaError(leptonica_output)
-
-        return False
-
-
-class LeptonicaError(Exception):
-    pass
-
-
-class LeptonicaIOError(LeptonicaError):
-    pass
-
-
-def pixRead(filename):
-    """Load an image file into a PIX object.
-
-    Leptonica can load TIFF, PNM (PBM, PGM, PPM), PNG, and JPEG.  If loading
-    fails then the object will wrap a C null pointer.
-
-    """
-    with LeptonicaErrorTrap():
-        return lept.pixRead(filename.encode(sys.getfilesystemencoding()))
-
-
-def pixScale(pix, scalex, scaley):
-    """Returns the pix object rescaled according to the proportions given."""
-    with LeptonicaErrorTrap():
-        return lept.pixScale(pix, scalex, scaley)
-
-
-def pixDeskew(pix, reduction_factor=0):
-    """Returns the deskewed pix object.
-
-    A clone of the original is returned when the algorithm cannot find a skew
-    angle with sufficient confidence.
-
-    reduction_factor -- amount to downsample (0 for default) when searching
-        for skew angle
-
-    """
-    with LeptonicaErrorTrap():
-        return lept.pixDeskew(pix, reduction_factor)
-
-
-def pixFindSkew(pix):
-    """Returns a tuple (deskew angle in degrees, confidence value).
-
-    Returns (None, None) if no angle is available.
-
-    """
-    with LeptonicaErrorTrap():
-        angle = C.c_float(0.0)
-        confidence = C.c_float(0.0)
-        result = lept.pixFindSkew(pix, C.byref(angle), C.byref(confidence))
-        if result == 0:
-            return (angle.value, confidence.value)
-        else:
-            return (None, None)
-
-
-def pixWriteImpliedFormat(filename, pix, jpeg_quality=0, jpeg_progressive=0):
-    """Write pix to the filename, with the extension indicating format.
-
-    jpeg_quality -- quality (iff JPEG; 1 - 100, 0 for default)
-    jpeg_progressive -- (iff JPEG; 0 for baseline seq., 1 for progressive)
-
-    """
-    fileroot, extension = os.path.splitext(filename)
-    fix_pnm = False
-    if extension.lower() in ('.pbm', '.pgm', '.ppm'):
-        # Leptonica does not process handle these extensions correctly, but
-        # does handle .pnm correctly.  Add another .pnm suffix.
-        filename += '.pnm'
-        fix_pnm = True
-
-    with LeptonicaErrorTrap():
-        lept.pixWriteImpliedFormat(
-            filename.encode(sys.getfilesystemencoding()),
-            pix, jpeg_quality, jpeg_progressive)
-
-    if fix_pnm:
-        from shutil import move
-        move(filename, filename[:-4])   # Remove .pnm suffix
-
-
-def pixDestroy(pix):
-    """Destroy the pix object.
-
-    Function signature is pixDestroy(struct Pix **), hence C.byref() to pass
-    the address of the pointer.
-
-    """
-    with LeptonicaErrorTrap():
-        lept.pixDestroy(C.byref(pix))
-
-
-def getLeptonicaVersion():
-    """Get Leptonica version string.
-
-    Caveat: Leptonica expects the caller to free this memory.  We don't,
-    since that would involve binding to libc to access libc.free(),
-    a pointless effort to reclaim 100 bytes of memory.
-
-    """
-    return lept.getLeptonicaVersion().decode()
-
-
-def deskew(infile, outfile, dpi):
-    try:
-        pix_source = pixRead(infile)
-    except LeptonicaIOError:
-        raise LeptonicaIOError("Failed to open file: %s" % infile)
-
-    if dpi < 150:
-        reduction_factor = 1  # Don't downsample too much if DPI is already low
-    else:
-        reduction_factor = 0  # Use default
-    pix_deskewed = pixDeskew(pix_source, reduction_factor)
-
-    try:
-        pixWriteImpliedFormat(outfile, pix_deskewed)
-    except LeptonicaIOError:
-        raise LeptonicaIOError("Failed to open destination file: %s" % outfile)
-    pixDestroy(pix_source)
-    pixDestroy(pix_deskewed)
-
-
-if __name__ == '__main__':
-    parser = argparse.ArgumentParser(
-        description="Python wrapper to access Leptonica")
-
-    subparsers = parser.add_subparsers(title='commands',
-                                       description='supported operations')
-
-    parser_deskew = subparsers.add_parser('deskew')
-    parser_deskew.add_argument('-r', '--dpi', dest='dpi', action='store',
-                               type=int, default=300, help='input resolution')
-    parser_deskew.add_argument('infile', help='image to deskew')
-    parser_deskew.add_argument('outfile', help='deskewed output image')
-    parser_deskew.set_defaults(func=deskew)
-
-    args = parser.parse_args()
-
-    if getLeptonicaVersion() != u'leptonica-1.69':
-        print("Unexpected leptonica version: %s" % getLeptonicaVersion())
-
-    args.func(args)
-
-
-def _test_output(mode, extension, im_format):
-    from PIL import Image
-    from tempfile import NamedTemporaryFile
-
-    with NamedTemporaryFile(prefix='test-lept-pnm', suffix=extension, delete=True) as tmpfile:
-        im = Image.new(mode=mode, size=(100, 100))
-        im.save(tmpfile)
-
-        pix = pixRead(tmpfile.name)
-        pixWriteImpliedFormat(tmpfile.name, pix)
-        pixDestroy(pix)
-
-        im_roundtrip = Image.open(tmpfile.name)
-        assert im_roundtrip.mode == im.mode, "leptonica mode differs"
-        assert im_roundtrip.format == im_format, \
-            "{0}: leptonica produced a {1}".format(
-                extension,
-                im_roundtrip.format)
-
-
-def test_pnm_output():
-    params = [['1', '.pbm', 'PPM'], ['L', '.pgm', 'PPM'],
-              ['RGB', '.ppm', 'PPM']]
-    for param in params:
-        _test_output(*param)
-
-
-def test_skew_angle():
-    from PIL import Image, ImageDraw
-    from tempfile import NamedTemporaryFile
-
-    im = Image.new(mode='1', size=(1000, 1000), color=1)
-
-    draw = ImageDraw.Draw(im)
-    for n in range(20):
-        draw.line([(50, 25 + 50*n), (950, 25 + 50*n)], width=1)
-    del draw
-
-    test_angles = [0.1 * ang for ang in range(1, 10)] + \
-                  [float(ang) for ang in range(1, 7)]
-    test_angles += [-ang for ang in test_angles]
-    test_angles = sorted(test_angles)
-
-    for rotate_angle in test_angles:
-        rotated_im = im.rotate(rotate_angle)
-        with NamedTemporaryFile(prefix='lept-skew', suffix='.png', delete=True) as tmpfile:
-            rotated_im.save(tmpfile)
-            pix = pixRead(tmpfile.name)
-            angle, confidence = pixFindSkew(pix)
-            pixDestroy(pix)
-            print('{0} {1}  {2}'.format(rotate_angle, angle, confidence), file=sys.stderr)
-
-

ocrmypdf/main.py

@@ -1,901 +0,0 @@
-#!/usr/bin/env python3
-# © 2015 James R. Barlow: github.com/jbarlow83
-
-from contextlib import suppress
-from tempfile import NamedTemporaryFile, mkdtemp
-import sys
-import os
-import fileinput
-import re
-import shutil
-import warnings
-import multiprocessing
-import atexit
-import textwrap
-
-import PyPDF2 as pypdf
-from PIL import Image
-
-from subprocess import Popen, check_call, PIPE, CalledProcessError, \
-    TimeoutExpired, check_output, STDOUT
-try:
-    from subprocess import DEVNULL
-except ImportError:
-    DEVNULL = open(os.devnull, 'wb')
-
-
-from ruffus import transform, suffix, merge, active_if, regex, jobs_limit, \
-    formatter, follows, split, collate, check_if_uptodate
-import ruffus.ruffus_exceptions as ruffus_exceptions
-import ruffus.cmdline as cmdline
-
-from .hocrtransform import HocrTransform
-from .pageinfo import pdf_get_all_pageinfo
-from .pdfa import generate_pdfa_def
-from . import ghostscript
-from . import tesseract
-from . import ExitCode
-
-warnings.simplefilter('ignore', pypdf.utils.PdfReadWarning)
-
-
-BASEDIR = os.path.dirname(os.path.realpath(__file__))
-JHOVE_PATH = os.path.realpath(os.path.join(BASEDIR, 'jhove'))
-JHOVE_JAR = os.path.join(JHOVE_PATH, 'bin', 'JhoveApp.jar')
-JHOVE_CFG = os.path.join(JHOVE_PATH, 'conf', 'jhove.conf')
-
-
-# -------------
-# External dependencies
-
-MINIMUM_TESS_VERSION = '3.02.02'
-
-
-def complain(message):
-    print(*textwrap.wrap(message), file=sys.stderr)
-
-
-if tesseract.version() < MINIMUM_TESS_VERSION:
-    complain(
-        "Please install tesseract {0} or newer "
-        "(currently installed version is {1})".format(
-            MINIMUM_TESS_VERSION, tesseract.version()))
-    sys.exit(ExitCode.missing_dependency)
-
-
-try:
-    import PIL.features
-    check_codec = PIL.features.check_codec
-except (ImportError, AttributeError):
-    def check_codec(codec_name):
-        if codec_name == 'jpg':
-            return 'jpeg_encoder' in dir(Image.core)
-        elif codec_name == 'zlib':
-            return 'zip_encoder' in dir(Image.core)
-        raise NotImplementedError(codec_name)
-
-
-def check_pil_encoder(codec_name, friendly_name):
-    try:
-        if check_codec(codec_name):
-            return
-    except Exception:
-        pass
-    complain(
-        "ERROR: Your version of the Python imaging library (Pillow) was "
-        "compiled without support for " + friendly_name + " encoding/decoding."
-        "\n"
-        "You will need to uninstall Pillow and reinstall it with PNG and JPEG "
-        "support (libjpeg and zlib)."
-        "\n"
-        "See installation instructions for your platform here:\n"
-        "    https://pillow.readthedocs.org/installation.html"
-    )
-    sys.exit(ExitCode.missing_dependency)
-
-
-check_pil_encoder('jpg', 'JPEG')
-check_pil_encoder('zlib', 'PNG')
-
-
-# -------------
-# Parser
-
-parser = cmdline.get_argparse(
-    prog="ocrmypdf",
-    description="Generate searchable PDF file from an image-only PDF file.",
-    version='3.0rc5',
-    fromfile_prefix_chars='@',
-    ignored_args=[
-        'touch_files_only', 'recreate_database', 'checksum_file_name',
-        'key_legend_in_graph', 'draw_graph_horizontally', 'flowchart_format',
-        'forced_tasks', 'target_tasks'])
-
-parser.add_argument(
-    'input_file',
-    help="PDF file containing the images to be OCRed")
-parser.add_argument(
-    'output_file',
-    help="output searchable PDF file")
-parser.add_argument(
-    '-l', '--language', action='append',
-    help="languages of the file to be OCRed")
-
-metadata = parser.add_argument_group(
-    "Metadata options",
-    "Set output PDF/A metadata (default: use input document's title)")
-metadata.add_argument(
-    '--title', type=str,
-    help="set document title (place multiple words in quotes)")
-metadata.add_argument(
-    '--author', type=str,
-    help="set document author")
-metadata.add_argument(
-    '--subject', type=str,
-    help="set document")
-metadata.add_argument(
-    '--keywords', type=str,
-    help="set document keywords")
-
-
-preprocessing = parser.add_argument_group(
-    "Preprocessing options",
-    "Improve OCR quality and final image")
-preprocessing.add_argument(
-    '-d', '--deskew', action='store_true',
-    help="deskew each page before performing OCR")
-preprocessing.add_argument(
-    '-c', '--clean', action='store_true',
-    help="clean pages from scanning artifacts before performing OCR")
-preprocessing.add_argument(
-    '-i', '--clean-final', action='store_true',
-    help="incorporate the cleaned image in the final PDF file")
-preprocessing.add_argument(
-    '--oversample', metavar='DPI', type=int, default=0,
-    help="oversample images to at least the specified DPI, to improve OCR "
-         "results slightly")
-
-parser.add_argument(
-    '-f', '--force-ocr', action='store_true',
-    help="rasterize any fonts or vector images on each page and apply OCR")
-parser.add_argument(
-    '-s', '--skip-text', action='store_true',
-    help="skip OCR on any pages that already contain text, but include the"
-         " page in final output")
-parser.add_argument(
-    '--skip-big', type=float, metavar='MPixels',
-    help="skip OCR on pages larger than the specified amount of megapixels, "
-         "but include skipped pages in final output")
-# parser.add_argument(
-#     '--exact-image', action='store_true',
-#     help="Use original page from PDF without re-rendering")
-
-advanced = parser.add_argument_group(
-    "Advanced",
-    "Advanced options for power users")
-advanced.add_argument(
-    '--tesseract-config', default=[], type=list, action='append',
-    help="additional Tesseract configuration files")
-advanced.add_argument(
-    '--pdf-renderer', choices=['tesseract', 'hocr'], default='hocr',
-    help='choose OCR PDF renderer')
-advanced.add_argument(
-    '--tesseract-timeout', default=180.0, type=float,
-    help='give up on OCR after the timeout, but copy the preprocessed page '
-         'into the final output')
-
-debugging = parser.add_argument_group(
-    "Debugging",
-    "Arguments to help with troubleshooting and debugging")
-debugging.add_argument(
-    '-k', '--keep-temporary-files', action='store_true',
-    help="keep temporary files (helpful for debugging)")
-debugging.add_argument(
-    '-g', '--debug-rendering', action='store_true',
-    help="render each page twice with debug information on second page")
-
-options = parser.parse_args()
-
-
-# ----------
-# Languages
-
-if not options.language:
-    options.language = ['eng']  # Enforce English hegemony
-
-# Support v2.x "eng+deu" language syntax
-if '+' in options.language[0]:
-    options.language = options.language[0].split('+')
-
-if not set(options.language).issubset(tesseract.languages()):
-    complain(
-        "The installed version of tesseract does not have language "
-        "data for the following requested languages: ")
-    for lang in (set(options.language) - tesseract.languages()):
-        complain(lang, file=sys.stderr)
-    sys.exit(ExitCode.bad_args)
-
-
-# ----------
-# Arguments
-
-
-if any((options.deskew, options.clean, options.clean_final)):
-    try:
-        from . import unpaper
-    except ImportError:
-        complain(
-            "Install the 'unpaper' program to use --deskew or --clean.")
-        sys.exit(ExitCode.bad_args)
-else:
-    unpaper = None
-
-if options.debug_rendering and options.pdf_renderer == 'tesseract':
-    complain(
-        "Ignoring --debug-rendering because it is not supported with"
-        "--pdf-renderer=tesseract.")
-
-if options.force_ocr and options.skip_text:
-    complain(
-        "Error: --force-ocr and --skip-text are mutually incompatible.")
-    sys.exit(ExitCode.bad_args)
-
-if options.clean and not options.clean_final \
-        and options.pdf_renderer == 'tesseract':
-    complain(
-        "Tesseract PDF renderer cannot render --clean pages without "
-        "also performing --clean-final, so --clean-final is assumed.")
-
-
-# ----------
-# Logging
-
-
-_logger, _logger_mutex = cmdline.setup_logging(__name__, options.log_file,
-                                               options.verbose)
-
-
-class WrappedLogger:
-
-    def __init__(self, my_logger, my_mutex):
-        self.logger = my_logger
-        self.mutex = my_mutex
-
-    def log(self, *args, **kwargs):
-        with self.mutex:
-            self.logger.log(*args, **kwargs)
-
-    def debug(self, *args, **kwargs):
-        with self.mutex:
-            self.logger.debug(*args, **kwargs)
-
-    def info(self, *args, **kwargs):
-        with self.mutex:
-            self.logger.info(*args, **kwargs)
-
-    def warning(self, *args, **kwargs):
-        with self.mutex:
-            self.logger.warning(*args, **kwargs)
-
-    def error(self, *args, **kwargs):
-        with self.mutex:
-            self.logger.error(*args, **kwargs)
-
-    def critical(self, *args, **kwargs):
-        with self.mutex:
-            self.logger.critical(*args, **kwargs)
-
-_log = WrappedLogger(_logger, _logger_mutex)
-
-
-def re_symlink(input_file, soft_link_name, log=_log):
-    """
-    Helper function: relinks soft symbolic link if necessary
-    """
-    # Guard against soft linking to oneself
-    if input_file == soft_link_name:
-        log.debug("Warning: No symbolic link made. You are using " +
-                  "the original data directory as the working directory.")
-        return
-
-    # Soft link already exists: delete for relink?
-    if os.path.lexists(soft_link_name):
-        # do not delete or overwrite real (non-soft link) file
-        if not os.path.islink(soft_link_name):
-            raise Exception("%s exists and is not a link" % soft_link_name)
-        try:
-            os.unlink(soft_link_name)
-        except:
-            log.debug("Can't unlink %s" % (soft_link_name))
-
-    if not os.path.exists(input_file):
-        raise Exception("trying to create a broken symlink to %s" % input_file)
-
-    log.debug("os.symlink(%s, %s)" % (input_file, soft_link_name))
-
-    # Create symbolic link using absolute path
-    os.symlink(
-        os.path.abspath(input_file),
-        soft_link_name
-    )
-
-
-# -------------
-# The Pipeline
-
-manager = multiprocessing.Manager()
-_pdfinfo = manager.list()
-_pdfinfo_lock = manager.Lock()
-
-work_folder = mkdtemp(prefix="com.github.ocrmypdf.")
-
-
-@atexit.register
-def cleanup_working_files(*args):
-    if options.keep_temporary_files:
-        print("Temporary working files saved at:")
-        print(work_folder)
-    else:
-        with suppress(FileNotFoundError):
-            shutil.rmtree(work_folder)
-
-
-@transform(
-    input=options.input_file,
-    filter=suffix('.pdf'),
-    output='.repaired.pdf',
-    output_dir=work_folder,
-    extras=[_log, _pdfinfo, _pdfinfo_lock])
-def repair_pdf(
-        input_file,
-        output_file,
-        log,
-        pdfinfo,
-        pdfinfo_lock):
-    args_qpdf = [
-        'qpdf', input_file, output_file
-    ]
-    try:
-        out = check_output(args_qpdf, stderr=STDOUT, universal_newlines=True)
-    except CalledProcessError as e:
-        if e.returncode == 2:
-            print("{0}: not a valid PDF, and could not repair it.".format(
-                    options.input_file))
-            print("Details:")
-            print(e.output)
-        else:
-            print(e.output)
-        sys.exit(ExitCode.input_file)
-
-    log.debug(out)
-
-    with pdfinfo_lock:
-        pdfinfo.extend(pdf_get_all_pageinfo(output_file))
-        log.info(pdfinfo)
-
-
-def get_pageinfo(input_file, pdfinfo, pdfinfo_lock):
-    pageno = int(os.path.basename(input_file)[0:6]) - 1
-    with pdfinfo_lock:
-        pageinfo = pdfinfo[pageno].copy()
-    return pageinfo
-
-
-def is_ocr_required(pageinfo, log):
-    page = pageinfo['pageno'] + 1
-    ocr_required = True
-    if not pageinfo['images']:
-        # If the page has no images, then it contains vector content or text
-        # or both. It seems quite unlikely that one would find meaningful text
-        # from rasterizing vector content. So skip the page.
-        log.info(
-            "Page {0} has no images - skipping OCR".format(page)
-        )
-        ocr_required = False
-    elif pageinfo['has_text']:
-        s = "Page {0} already has text! – {1}"
-
-        if not options.force_ocr and not options.skip_text:
-            log.error(s.format(page,
-                               "aborting (use --force-ocr to force OCR)"))
-            sys.exit(ExitCode.already_done_ocr)
-        elif options.force_ocr:
-            log.info(s.format(page,
-                              "rasterizing text and running OCR anyway"))
-            ocr_required = True
-        elif options.skip_text:
-            log.info(s.format(page,
-                              "skipping all processing on this page"))
-            ocr_required = False
-
-    if ocr_required and options.skip_big:
-        pixel_count = pageinfo['width_pixels'] * pageinfo['height_pixels']
-        if pixel_count > (options.skip_big * 1000000):
-            ocr_required = False
-            log.info(
-                "Page {0} is very large; skipping due to -b".format(page))
-
-    return ocr_required
-
-
-@split(
-    repair_pdf,
-    os.path.join(work_folder, '*.page.pdf'),
-    extras=[_log, _pdfinfo, _pdfinfo_lock])
-def split_pages(
-        input_file,
-        output_files,
-        log,
-        pdfinfo,
-        pdfinfo_lock):
-
-    for oo in output_files:
-        with suppress(FileNotFoundError):
-            os.unlink(oo)
-
-    pages = check_output(['qpdf', '--show-npages', input_file],
-                         universal_newlines=True, close_fds=True)
-
-    for n in range(int(pages)):
-        args_qpdf = [
-            'qpdf', input_file,
-            '--pages', input_file, '{0}'.format(n + 1), '--',
-            os.path.join(work_folder, '{0:06d}.page.pdf'.format(n + 1))
-        ]
-        check_call(args_qpdf)
-
-    from glob import glob
-    for filename in glob(os.path.join(work_folder, '*.page.pdf')):
-        pageinfo = get_pageinfo(filename, pdfinfo, pdfinfo_lock)
-
-        alt_suffix = '.ocr.page.pdf' if is_ocr_required(pageinfo, log) \
-                     else '.skip.page.pdf'
-        re_symlink(
-            filename,
-            os.path.join(
-                work_folder,
-                os.path.basename(filename)[0:6] + alt_suffix))
-
-
-@transform(
-    input=split_pages,
-    filter=suffix('.ocr.page.pdf'),
-    output='.page.png',
-    output_dir=work_folder,
-    extras=[_log, _pdfinfo, _pdfinfo_lock])
-def rasterize_with_ghostscript(
-        input_file,
-        output_file,
-        log,
-        pdfinfo,
-        pdfinfo_lock):
-
-    pageinfo = get_pageinfo(input_file, pdfinfo, pdfinfo_lock)
-
-    device = 'png16m'  # 24-bit
-    if all(image['comp'] == 1 for image in pageinfo['images']):
-        if all(image['bpc'] == 1 for image in pageinfo['images']):
-            device = 'pngmono'
-        elif not any(image['color'] == 'color'
-                     for image in pageinfo['images']):
-            device = 'pnggray'
-
-    xres = max(pageinfo['xres'], options.oversample or 0)
-    yres = max(pageinfo['yres'], options.oversample or 0)
-
-    ghostscript.rasterize_pdf(input_file, output_file, xres, yres, device, log)
-
-
-@transform(
-    input=rasterize_with_ghostscript,
-    filter=suffix(".page.png"),
-    output=".pp-deskew.png",
-    extras=[_log, _pdfinfo, _pdfinfo_lock])
-def preprocess_deskew(
-        input_file,
-        output_file,
-        log,
-        pdfinfo,
-        pdfinfo_lock):
-
-    if not options.deskew:
-        re_symlink(input_file, output_file, log)
-        return
-
-    pageinfo = get_pageinfo(input_file, pdfinfo, pdfinfo_lock)
-    dpi = int(pageinfo['xres'])
-
-    unpaper.deskew(input_file, output_file, dpi, log)
-
-
-@transform(
-    input=preprocess_deskew,
-    filter=suffix(".pp-deskew.png"),
-    output=".pp-clean.png",
-    extras=[_log, _pdfinfo, _pdfinfo_lock])
-def preprocess_clean(
-        input_file,
-        output_file,
-        log,
-        pdfinfo,
-        pdfinfo_lock):
-
-    if not options.clean:
-        re_symlink(input_file, output_file, log)
-        return
-
-    pageinfo = get_pageinfo(input_file, pdfinfo, pdfinfo_lock)
-    dpi = int(pageinfo['xres'])
-
-    unpaper.clean(input_file, output_file, dpi, log)
-
-
-@active_if(options.pdf_renderer == 'hocr')
-@transform(
-    input=preprocess_clean,
-    filter=suffix(".pp-clean.png"),
-    output=".hocr",
-    extras=[_log, _pdfinfo, _pdfinfo_lock])
-def ocr_tesseract_hocr(
-        input_file,
-        output_file,
-        log,
-        pdfinfo,
-        pdfinfo_lock):
-
-    pageinfo = get_pageinfo(input_file, pdfinfo, pdfinfo_lock)
-
-    args_tesseract = [
-        'tesseract',
-        '-l', '+'.join(options.language),
-        input_file,
-        output_file,
-        'hocr'
-    ] + options.tesseract_config
-    p = Popen(args_tesseract, close_fds=True, stdout=PIPE, stderr=PIPE,
-              universal_newlines=True)
-    try:
-        stdout, stderr = p.communicate(timeout=options.tesseract_timeout)
-    except TimeoutExpired:
-        p.kill()
-        stdout, stderr = p.communicate()
-        # Generate a HOCR file with no recognized text if tesseract times out
-        # Temporary workaround to hocrTransform not being able to function if
-        # it does not have a valid hOCR file.
-        with open(output_file, 'w', encoding="utf-8") as f:
-            f.write(tesseract.HOCR_TEMPLATE.format(
-                pageinfo['width_pixels'],
-                pageinfo['height_pixels']))
-    else:
-        if stdout:
-            log.info(stdout)
-        if stderr:
-            log.error(stderr)
-
-        if p.returncode != 0:
-            raise CalledProcessError(p.returncode, args_tesseract)
-
-        if os.path.exists(output_file + '.html'):
-            # Tesseract 3.02 appends suffix ".html" on its own (.hocr.html)
-            shutil.move(output_file + '.html', output_file)
-        elif os.path.exists(output_file + '.hocr'):
-            # Tesseract 3.03 appends suffix ".hocr" on its own (.hocr.hocr)
-            shutil.move(output_file + '.hocr', output_file)
-
-        # Tesseract 3.03 inserts source filename into hocr file without
-        # escaping it, creating invalid XML and breaking the parser.
-        # As a workaround, rewrite the hocr file, replacing the filename
-        # with a space.
-        regex_nested_single_quotes = re.compile(
-            r"""title='image "([^"]*)";""")
-        with fileinput.input(files=(output_file,), inplace=True) as f:
-            for line in f:
-                line = regex_nested_single_quotes.sub(
-                    r"""title='image " ";""", line)
-                print(line, end='')  # fileinput.input redirects stdout
-
-
-@active_if(options.pdf_renderer == 'hocr')
-@collate(
-    input=[rasterize_with_ghostscript, preprocess_deskew, preprocess_clean],
-    filter=regex(r".*/(\d{6})(?:\.page|\.pp-deskew|\.pp-clean)\.png"),
-    output=os.path.join(work_folder, r'\1.image'),
-    extras=[_log, _pdfinfo, _pdfinfo_lock])
-def select_image_for_pdf(
-        infiles,
-        output_file,
-        log,
-        pdfinfo,
-        pdfinfo_lock):
-    if options.clean_final:
-        image_suffix = '.pp-clean.png'
-    elif options.deskew:
-        image_suffix = '.pp-deskew.png'
-    else:
-        image_suffix = '.page.png'
-    image = next(ii for ii in infiles if ii.endswith(image_suffix))
-
-    pageinfo = get_pageinfo(image, pdfinfo, pdfinfo_lock)
-    if all(image['enc'] == 'jpeg' for image in pageinfo['images']):
-        # If all images were JPEGs originally, produce a JPEG as output
-        Image.open(image).save(output_file, format='JPEG')
-    else:
-        re_symlink(image, output_file)
-
-
-@active_if(options.pdf_renderer == 'hocr')
-@collate(
-    input=[select_image_for_pdf, ocr_tesseract_hocr],
-    filter=regex(r".*/(\d{6})(?:\.image|\.hocr)"),
-    output=os.path.join(work_folder, r'\1.rendered.pdf'),
-    extras=[_log, _pdfinfo, _pdfinfo_lock])
-def render_hocr_page(
-        infiles,
-        output_file,
-        log,
-        pdfinfo,
-        pdfinfo_lock):
-    hocr = next(ii for ii in infiles if ii.endswith('.hocr'))
-    image = next(ii for ii in infiles if ii.endswith('.image'))
-
-    pageinfo = get_pageinfo(image, pdfinfo, pdfinfo_lock)
-    dpi = round(max(pageinfo['xres'], pageinfo['yres'], options.oversample))
-
-    hocrtransform = HocrTransform(hocr, dpi)
-    hocrtransform.to_pdf(output_file, imageFileName=image,
-                         showBoundingboxes=False, invisibleText=True)
-
-
-@active_if(options.pdf_renderer == 'hocr')
-@active_if(options.debug_rendering)
-@collate(
-    input=[select_image_for_pdf, ocr_tesseract_hocr],
-    filter=regex(r".*/(\d{6})(?:\.image|\.hocr)"),
-    output=os.path.join(work_folder, r'\1.debug.pdf'),
-    extras=[_log, _pdfinfo, _pdfinfo_lock])
-def render_hocr_debug_page(
-        infiles,
-        output_file,
-        log,
-        pdfinfo,
-        pdfinfo_lock):
-    hocr = next(ii for ii in infiles if ii.endswith('.hocr'))
-    image = next(ii for ii in infiles if ii.endswith('.image'))
-
-    pageinfo = get_pageinfo(image, pdfinfo, pdfinfo_lock)
-    dpi = round(max(pageinfo['xres'], pageinfo['yres'], options.oversample))
-
-    hocrtransform = HocrTransform(hocr, dpi)
-    hocrtransform.to_pdf(output_file, imageFileName=None,
-                         showBoundingboxes=True, invisibleText=False)
-
-
-@active_if(options.pdf_renderer == 'tesseract')
-@collate(
-    input=[preprocess_clean, split_pages],
-    filter=regex(r".*/(\d{6})(?:\.pp-clean\.png|\.page\.pdf)"),
-    output=os.path.join(work_folder, r'\1.rendered.pdf'),
-    extras=[_log, _pdfinfo, _pdfinfo_lock])
-def tesseract_ocr_and_render_pdf(
-        input_files,
-        output_file,
-        log,
-        pdfinfo,
-        pdfinfo_lock):
-
-    input_image = next((ii for ii in input_files if ii.endswith('.png')), '')
-    input_pdf = next((ii for ii in input_files if ii.endswith('.pdf')))
-    if not input_image:
-        # Skipping this page
-        re_symlink(input_pdf, output_file)
-        return
-
-    args_tesseract = [
-        'tesseract',
-        '-l', '+'.join(options.language),
-        input_image,
-        os.path.splitext(output_file)[0],  # Tesseract appends suffix
-        'pdf'
-    ] + options.tesseract_config
-    p = Popen(args_tesseract, close_fds=True, stdout=PIPE, stderr=PIPE,
-              universal_newlines=True)
-
-    try:
-        stdout, stderr = p.communicate(timeout=options.tesseract_timeout)
-        if stdout:
-            log.info(stdout)
-        if stderr:
-            log.error(stderr)
-    except TimeoutExpired:
-        p.kill()
-        log.info("Tesseract - page timed out")
-        re_symlink(input_pdf, output_file)
-
-
-@transform(
-    input=repair_pdf,
-    filter=suffix('.repaired.pdf'),
-    output='.pdfa_def.ps',
-    output_dir=work_folder,
-    extras=[_log])
-def generate_postscript_stub(
-        input_file,
-        output_file,
-        log):
-
-    pdf = pypdf.PdfFileReader(input_file)
-
-    def from_document_info(key):
-        # pdf.documentInfo.get() DOES NOT work as expected
-        try:
-            s = pdf.documentInfo[key]
-            return str(s)
-        except KeyError:
-            return ''
-
-    pdfmark = {
-        'title': from_document_info('/Title'),
-        'author': from_document_info('/Author'),
-        'keywords': from_document_info('/Keywords'),
-        'subject': from_document_info('/Subject'),
-    }
-    if options.title:
-        pdfmark['title'] = options.title
-    if options.author:
-        pdfmark['author'] = options.author
-    if options.keywords:
-        pdfmark['keywords'] = options.keywords
-    if options.subject:
-        pdfmark['subject'] = options.subject
-
-    generate_pdfa_def(output_file, pdfmark)
-
-
-@transform(
-    input=split_pages,
-    filter=suffix('.skip.page.pdf'),
-    output='.done.pdf',
-    output_dir=work_folder,
-    extras=[_log])
-def skip_page(
-        input_file,
-        output_file,
-        log):
-    re_symlink(input_file, output_file, log)
-
-
-@merge(
-    input=[render_hocr_page, render_hocr_debug_page, skip_page,
-           tesseract_ocr_and_render_pdf, generate_postscript_stub],
-    output=os.path.join(work_folder, 'merged.pdf'),
-    extras=[_log, _pdfinfo, _pdfinfo_lock])
-def merge_pages(
-        input_files,
-        output_file,
-        log,
-        pdfinfo,
-        pdfinfo_lock):
-
-    def input_file_order(s):
-        '''Sort order: All rendered pages followed
-        by their debug page, if any, followed by Postscript stub.
-        Ghostscript documentation has the Postscript stub at the
-        beginning, but it works at the end and also gets document info
-        right that way.'''
-        if s.endswith('.ps'):
-            return 99999999
-        key = int(os.path.basename(s)[0:6]) * 10
-        if 'debug' in os.path.basename(s):
-            key += 1
-        return key
-
-    pdf_pages = sorted(input_files, key=input_file_order)
-    log.info(pdf_pages)
-    ghostscript.generate_pdfa(pdf_pages, output_file, options.jobs or 1)
-
-
-@transform(
-    input=merge_pages,
-    filter=formatter(),
-    output=options.output_file,
-    extras=[_log, _pdfinfo, _pdfinfo_lock])
-def copy_final(
-        input_file,
-        output_file,
-        log,
-        pdfinfo,
-        pdfinfo_lock):
-    shutil.copy(input_file, output_file)
-
-
-def validate_pdfa(
-        input_file,
-        log):
-
-    args_qpdf = [
-        'qpdf',
-        '--check',
-        input_file
-    ]
-
-    try:
-        check_output(args_qpdf, stderr=STDOUT, universal_newlines=True)
-    except CalledProcessError as e:
-        if e.returncode == 2:
-            print("{0}: not a valid PDF, and could not repair it.".format(
-                    options.input_file))
-            print("Details:")
-            print(e.output)
-        elif e.returncode == 3:
-            log.info("qpdf --check returned warnings:")
-            log.info(e.output)
-        else:
-            print(e.output)
-        return False
-
-    return True
-
-
-# @active_if(ocr_required and options.exact_image)
-# @merge([render_hocr_blank_page, extract_single_page],
-#        os.path.join(work_folder, "%04i.merged.pdf") % pageno)
-# def merge_hocr_with_original_page(infiles, output_file):
-#     with open(infiles[0], 'rb') as hocr_input, \
-#             open(infiles[1], 'rb') as page_input, \
-#             open(output_file, 'wb') as output:
-#         hocr_reader = pypdf.PdfFileReader(hocr_input)
-#         page_reader = pypdf.PdfFileReader(page_input)
-#         writer = pypdf.PdfFileWriter()
-
-#         the_page = hocr_reader.getPage(0)
-#         the_page.mergePage(page_reader.getPage(0))
-#         writer.addPage(the_page)
-#         writer.write(output)
-
-
-def available_cpu_count():
-    try:
-        return multiprocessing.cpu_count()
-    except NotImplementedError:
-        pass
-
-    try:
-        import psutil
-        return psutil.cpu_count()
-    except (ImportError, AttributeError):
-        pass
-
-    complain(
-        "Could not get CPU count.  Assuming one (1) CPU."
-        "Use -j N to set manually.")
-    return 1
-
-
-def run_pipeline():
-    if not options.jobs or options.jobs == 1:
-        options.jobs = available_cpu_count()
-
-    try:
-        cmdline.run(options)
-    except ruffus_exceptions.RethrownJobError as e:
-        if options.verbose:
-            print(e)
-
-        # Yuck. Hunt through the ruffus exception to find out what the
-        # return code is supposed to be.
-        for exc in e.args:
-            task_name, job_name, exc_name, exc_value, exc_stack = exc
-            if exc_name == 'builtins.SystemExit':
-                return eval(
-                    exc_value,
-                    {'ExitCode': ExitCode}, {'exc_value': exc_value})
-
-    if not validate_pdfa(options.output_file, _log):
-        _log.warning('Output file: The generated PDF/A file is INVALID')
-        return ExitCode.invalid_output_pdfa
-
-    return ExitCode.ok
-
-
-if __name__ == '__main__':
-    sys.exit(run_pipeline())

ocrmypdf/pageinfo.py

@@ -1,144 +0,0 @@
-#!/usr/bin/env python3
-# © 2015 James R. Barlow: github.com/jbarlow83
-
-from subprocess import Popen, PIPE
-from decimal import Decimal, getcontext
-import re
-import sys
-import PyPDF2 as pypdf
-
-
-FRIENDLY_COLORSPACE = {
-    '/DeviceGray': 'gray',
-    '/CalGray': 'gray',
-    '/DeviceRGB': 'rgb',
-    '/CalRGB': 'rgb',
-    '/DeviceCMYK': 'cmyk',
-    '/Lab': 'lab',
-    '/ICCBased': 'icc',
-    '/Indexed': 'index',
-    '/Separation': 'sep',
-    '/DeviceN': 'devn',
-    '/Pattern': '-'
-}
-
-FRIENDLY_ENCODING = {
-    '/CCITTFaxDecode': 'ccitt',
-    '/DCTDecode': 'jpeg',
-    '/JPXDecode': 'jpx',
-    '/JBIG2Decode': 'jbig2',
-}
-
-FRIENDLY_COMP = {
-    'gray': 1,
-    'rgb': 3,
-    'cmyk': 4,
-    'lab': 3,
-}
-
-
-def _page_has_inline_images(page):
-    # PDF always uses \r\n for separator regardless of platform
-    # Really basic heuristic that might trigger the odd false positive
-    # This is only finds the first image and is not quite spec compliant
-    try:
-        contents = page.getContents()
-        data = contents.getData()
-    except AttributeError:
-        # If we can't access the contents or data (empty page?) then there
-        # are no inline images
-        return False
-
-    begin_image, image_data, end_image = False, False, False
-    for data in re.split(b'\s+', data):
-        if data == b'BI':
-            begin_image = True
-        elif data == b'ID':
-            image_data = True
-        elif data == b'EI':
-            end_image = True
-        if all((begin_image, image_data, end_image)):
-            return True
-    return False
-
-
-def _find_page_images(page, pageinfo):
-    try:
-        page['/Resources']['/XObject']
-    except KeyError:
-        return
-
-    # Look for XObject (out of line images)
-    for xobj in page['/Resources']['/XObject']:
-        # PyPDF2 returns the keys as an iterator
-        pdfimage = page['/Resources']['/XObject'][xobj]
-        if pdfimage['/Subtype'] != '/Image':
-            continue
-        if '/ImageMask' in pdfimage:
-            if pdfimage['/ImageMask']:
-                continue
-        image = {}
-        image['width'] = pdfimage['/Width']
-        image['height'] = pdfimage['/Height']
-        image['bpc'] = pdfimage['/BitsPerComponent']
-        if '/Filter' in pdfimage:
-            filter_ = pdfimage['/Filter']
-            if isinstance(filter_, pypdf.generic.ArrayObject):
-                filter_ = filter_[0]
-            image['enc'] = FRIENDLY_ENCODING.get(filter_, 'image')
-        else:
-            image['enc'] = 'image'
-        if '/ColorSpace' in pdfimage:
-            cs = pdfimage['/ColorSpace']
-            if isinstance(cs, pypdf.generic.ArrayObject):
-                cs = cs[0]
-            image['color'] = FRIENDLY_COLORSPACE.get(cs, '-')
-        else:
-            image['color'] = 'jpx' if image['enc'] == 'jpx' else '?'
-
-        image['comp'] = FRIENDLY_COMP.get(image['color'], '?')
-        image['dpi_w'] = image['width'] / pageinfo['width_inches']
-        image['dpi_h'] = image['height'] / pageinfo['height_inches']
-        image['dpi'] = (image['dpi_w'] * image['dpi_h']) ** Decimal(0.5)
-        yield image
-
-
-def _pdf_get_pageinfo(infile, page: int):
-    pageinfo = {}
-    pageinfo['pageno'] = page
-    pageinfo['images'] = []
-
-    pdf = pypdf.PdfFileReader(infile)
-    page = pdf.pages[page - 1]
-
-    text = page.extractText()
-    pageinfo['has_text'] = (text.strip() != '')
-
-    width_pt = page['/MediaBox'][2] - page['/MediaBox'][0]
-    height_pt = page['/MediaBox'][3] - page['/MediaBox'][1]
-    pageinfo['width_inches'] = width_pt / Decimal(72.0)
-    pageinfo['height_inches'] = height_pt / Decimal(72.0)
-
-    pageinfo['images'] = [im for im in _find_page_images(page, pageinfo)]
-
-    # Look for inline images
-    if _page_has_inline_images(page):
-        raise NotImplementedError(
-            "Warning: input PDF contains inline images - not supported")
-
-    if pageinfo['images']:
-        xres = max(image['dpi_w'] for image in pageinfo['images'])
-        yres = max(image['dpi_h'] for image in pageinfo['images'])
-        pageinfo['xres'], pageinfo['yres'] = xres, yres
-        pageinfo['width_pixels'] = \
-            int(round(xres * pageinfo['width_inches']))
-        pageinfo['height_pixels'] = \
-            int(round(yres * pageinfo['height_inches']))
-
-    return pageinfo
-
-
-def pdf_get_all_pageinfo(infile):
-    pdf = pypdf.PdfFileReader(infile)
-    getcontext().prec = 6
-    return [_pdf_get_pageinfo(infile, n) for n in range(pdf.numPages)]

ocrmypdf/pdfa.py

@@ -1,130 +0,0 @@
-#!/usr/bin/env python3
-# © 2015 James R. Barlow: github.com/jbarlow83
-#
-# Generate a PDFA_def.ps file for Ghostscript >= 9.14
-
-from __future__ import print_function, absolute_import, division
-from string import Template
-from subprocess import Popen, PIPE
-import os
-import codecs
-
-
-# This is a template written in PostScript which is needed to create PDF/A
-# files, from the Ghostscript documentation. Lines beginning with % are
-# comments. Python substitution variables have a '$' prefix.
-pdfa_def_template = u"""%!
-% This is a sample prefix file for creating a PDF/A document.
-% Feel free to modify entries marked with "Customize".
-% This assumes an ICC profile to reside in the file (ISO Coated sb.icc),
-% unless the user modifies the corresponding line below.
-
-% Define entries in the document Info dictionary :
-/ICCProfile ($icc_profile)
-def
-
-[ /Title <$title>
-  /Author <$author>
-  /Subject <$subject>
-  /Keywords <$keywords>
-  /DOCINFO pdfmark
-
-% Define an ICC profile :
-
-[/_objdef {icc_PDFA} /type /stream /OBJ pdfmark
-[{icc_PDFA}
-<<
-  /N currentpagedevice /ProcessColorModel known {
-    currentpagedevice /ProcessColorModel get dup /DeviceGray eq
-    {pop 1} {
-      /DeviceRGB eq
-      {3}{4} ifelse
-    } ifelse
-  } {
-    (ERROR, unable to determine ProcessColorModel) == flush
-  } ifelse
->> /PUT pdfmark
-[{icc_PDFA} ICCProfile (r) file /PUT pdfmark
-
-% Define the output intent dictionary :
-
-[/_objdef {OutputIntent_PDFA} /type /dict /OBJ pdfmark
-[{OutputIntent_PDFA} <<
-  /Type /OutputIntent             % Must be so (the standard requires).
-  /S /GTS_PDFA1                   % Must be so (the standard requires).
-  /DestOutputProfile {icc_PDFA}            % Must be so (see above).
-  /OutputConditionIdentifier ($icc_identifier)
->> /PUT pdfmark
-[{Catalog} <</OutputIntents [ {OutputIntent_PDFA} ]>> /PUT pdfmark
-"""
-
-
-def encode_text_string(s: str) -> str:
-    '''Encode text string to hex string for use in a PDF
-
-    From PDF 32000-1:2008 a string object may be included in hexademical form
-    if it is enclosed in angle brackets.  For general Unicode the string should
-    be UTF-16 (big endian) with byte order marks.  A non-hexademical
-    representation is doable but this is preferable since it allows the output
-    Postscript file to be completely ASCII and no escaping of Postscript
-    characters is necessary.
-    '''
-    if s == '':
-        return ''
-    utf16_bytes = s.encode('utf-16be')
-    ascii_hex_bytes = codecs.encode(b'\xfe\xff' + utf16_bytes, 'hex')
-    ascii_hex_str = ascii_hex_bytes.decode('ascii').lower()
-    return ascii_hex_str
-
-
-def _get_pdfa_def(icc_profile, icc_identifier, pdfmark):
-    pdfmark_utf16 = {k: encode_text_string(v) for k, v in pdfmark.items()}
-
-    t = Template(pdfa_def_template)
-    result = t.substitute(icc_profile=icc_profile,
-                          icc_identifier=icc_identifier,
-                          title=pdfmark_utf16.get('title', ''),
-                          author=pdfmark_utf16.get('author', ''),
-                          subject=pdfmark_utf16.get('subject', ''),
-                          keywords=pdfmark_utf16.get('keywords', ''))
-    return result
-
-
-def _get_postscript_icc_path():
-    "Parse Ghostscript's help message to find where iccprofiles are stored"
-
-    p_gs = Popen(['gs', '--help'], close_fds=True, universal_newlines=True,
-                 stdout=PIPE, stderr=PIPE)
-    out, _ = p_gs.communicate()
-    lines = out.splitlines()
-
-    def search_paths(lines):
-        seeking = True
-        for line in lines:
-            if seeking:
-                if line.startswith('Search path'):
-                    seeking = False
-                    continue
-            else:
-                if line.strip().startswith('/'):
-                    yield from (
-                        path.strip() for path in line.split(':')
-                        if path.strip() != '')
-    for root in search_paths(lines):
-        path = os.path.realpath(os.path.join(root, '../iccprofiles'))
-        if os.path.exists(path):
-            return path
-
-
-def generate_pdfa_def(target_filename, pdfmark, icc='sRGB'):
-    if icc == 'sRGB':
-        icc_profile = os.path.join(_get_postscript_icc_path(), 'srgb.icc')
-    else:
-        raise NotImplementedError("Only supporting sRGB")
-
-    ps = _get_pdfa_def(icc_profile, icc, pdfmark)
-
-    # Since PostScript might not handle UTF-8 (it's hard to get a clear
-    # answer), insist on ascii
-    with open(target_filename, 'w', encoding='ascii') as f:
-        f.write(ps)

ocrmypdf/tesseract.py

@@ -1,69 +0,0 @@
-#!/usr/bin/env python3
-# © 2015 James R. Barlow: github.com/jbarlow83
-
-from subprocess import STDOUT, CalledProcessError, check_output
-import sys
-import os
-import re
-from functools import lru_cache
-from . import ExitCode
-
-
-@lru_cache(maxsize=1)
-def version():
-    args_tess = [
-        'tesseract',
-        '--version'
-    ]
-    try:
-        versions = check_output(
-                args_tess, close_fds=True, universal_newlines=True,
-                stderr=STDOUT)
-    except CalledProcessError:
-        print("Could not find Tesseract executable on system PATH.")
-        sys.exit(ExitCode.missing_dependency)
-
-    tesseract_version = re.match(r'tesseract\s(.+)', versions).group(1)
-    return tesseract_version
-
-
-@lru_cache(maxsize=1)
-def languages():
-    args_tess = [
-        'tesseract',
-        '--list-langs'
-    ]
-    try:
-        langs = check_output(
-                args_tess, close_fds=True, universal_newlines=True,
-                stderr=STDOUT)
-    except CalledProcessError as e:
-        print("Tesseract failed to report available languages.")
-        print("Output from Tesseract:")
-        print("-" * 40)
-        print(e.output)
-        sys.exit(ExitCode.missing_dependency)
-    return set(lang.strip() for lang in langs.splitlines()[1:])
-
-
-HOCR_TEMPLATE = '''<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
-    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
- <head>
-  <title></title>
-  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
-  <meta name='ocr-system' content='tesseract 3.02.02' />
-  <meta name='ocr-capabilities' content='ocr_page ocr_carea ocr_par ocr_line ocrx_word'/>
- </head>
- <body>
-  <div class='ocr_page' id='page_1' title='image "x.tif"; bbox 0 0 {0} {1}; ppageno 0'>
-   <div class='ocr_carea' id='block_1_1' title="bbox 0 1 {0} {1}">
-    <p class='ocr_par' dir='ltr' id='par_1' title="bbox 0 1 {0} {1}">
-     <span class='ocr_line' id='line_1' title="bbox 0 1 {0} {1}"><span class='ocrx_word' id='word_1' title="bbox 0 1 {0} {1}"> </span>
-     </span>
-    </p>
-   </div>
-  </div>
- </body>
-</html>'''

ocrmypdf/test/test_pageinfo.py

@@ -1,108 +0,0 @@
-#!/usr/bin/env python3
-# © 2015 James R. Barlow: github.com/jbarlow83
-
-from ocrmypdf import pageinfo
-from reportlab.pdfgen.canvas import Canvas
-from PIL import Image
-from tempfile import NamedTemporaryFile
-from contextlib import suppress
-import os
-import sys
-import shutil
-import pytest
-import img2pdf
-from pkg_resources import Requirement, resource_filename
-
-req = Requirement.parse('ocrmypdf')
-
-TEST_OUTPUT = os.path.join(os.path.dirname(__file__), 'output')
-
-
-def setup_module():
-    with suppress(FileNotFoundError):
-        shutil.rmtree(TEST_OUTPUT)
-    with suppress(FileExistsError):
-        os.mkdir(TEST_OUTPUT)
-
-
-def test_single_page_text():
-    filename = os.path.join(TEST_OUTPUT, 'text.pdf')
-    pdf = Canvas(filename, pagesize=(8*72, 6*72))
-    text = pdf.beginText()
-    text.setFont('Helvetica', 12)
-    text.setTextOrigin(1*72, 3*72)
-    text.textLine("Methink'st thou art a general offence and every"
-                  " man should beat thee.")
-    pdf.drawText(text)
-    pdf.showPage()
-    pdf.save()
-
-    pdfinfo = pageinfo.pdf_get_all_pageinfo(filename)
-
-    assert len(pdfinfo) == 1
-    page = pdfinfo[0]
-
-    assert page['has_text']
-    assert len(page['images']) == 0
-
-
-def test_single_page_image():
-    filename = os.path.join(TEST_OUTPUT, 'image-mono.pdf')
-
-    with NamedTemporaryFile() as im_tmp:
-        im = Image.new('1', (8, 8), 0)
-        for n in range(8):
-            im.putpixel((n, n), 1)
-        im.save(im_tmp.name, format='PNG')
-
-        pdf_bytes = img2pdf.convert([im_tmp.name], dpi=8)
-        with open(filename, 'wb') as pdf:
-            pdf.write(pdf_bytes)
-
-    pdfinfo = pageinfo.pdf_get_all_pageinfo(filename)
-
-    assert len(pdfinfo) == 1
-    page = pdfinfo[0]
-
-    assert not page['has_text']
-    assert len(page['images']) == 1
-
-    pdfimage = page['images'][0]
-    assert pdfimage['width'] == 8
-    assert pdfimage['color'] == 'gray'
-
-    # While unexpected, this is correct
-    # PDF spec says /FlateDecode image must have /BitsPerComponent 8
-    # So mono images get upgraded to 8-bit
-    assert pdfimage['bpc'] == 8
-
-    # DPI in a 1"x1" is the image width
-    assert pdfimage['dpi_w'] == 8
-    assert pdfimage['dpi_h'] == 8
-
-
-def test_single_page_inline_image():
-    filename = os.path.join(TEST_OUTPUT, 'image-mono-inline.pdf')
-    pdf = Canvas(filename, pagesize=(8*72, 6*72))
-    with NamedTemporaryFile() as im_tmp:
-        im = Image.new('1', (8, 8), 0)
-        for n in range(8):
-            im.putpixel((n, n), 1)
-        im.save(im_tmp.name, format='PNG')
-        # Draw image in a 72x72 pt or 1"x1" area
-        pdf.drawInlineImage(im_tmp.name, 0, 0, width=72, height=72)
-        pdf.showPage()
-        pdf.save()
-
-    with pytest.raises(NotImplementedError):
-        pageinfo.pdf_get_all_pageinfo(filename)
-
-
-def test_jpeg():
-    filename = resource_filename(req, 'tests/resources/c02-22.pdf')
-
-    pdfinfo = pageinfo.pdf_get_all_pageinfo(filename)
-
-    pdfimage = pdfinfo[0]['images'][0]
-    assert pdfimage['enc'] == 'jpeg'
-

ocrmypdf/unpaper.py

@@ -1,84 +0,0 @@
-#!/usr/bin/env python3
-# © 2015 James R. Barlow: github.com/jbarlow83
-# unpaper documentation:
-# https://github.com/Flameeyes/unpaper/blob/master/doc/basic-concepts.md
-
-from subprocess import Popen, PIPE
-from tempfile import NamedTemporaryFile
-import sys
-import os
-from functools import lru_cache
-
-
-@lru_cache(maxsize=1)
-def version():
-    args_unpaper = [
-        'unpaper',
-        '--version'
-    ]
-    p_unpaper = Popen(args_unpaper, close_fds=True, universal_newlines=True,
-                      stdout=PIPE, stderr=PIPE)
-    version, _ = p_unpaper.communicate(timeout=5)
-
-    return version.strip()
-
-
-try:
-    from PIL import Image
-except ImportError:
-    print("Could not find Python3 imaging library", file=sys.stderr)
-    raise
-
-
-def run(input_file, output_file, dpi, log, mode_args):
-    args_unpaper = [
-        'unpaper',
-        '-v',
-        '--dpi', str(dpi)
-    ] + mode_args
-
-    SUFFIXES = {'1': '.pbm', 'L': '.pgm', 'RGB': '.ppm'}
-    suffix = ''
-
-    im = Image.open(input_file)
-    suffix = SUFFIXES[im.mode]
-    with NamedTemporaryFile(suffix=suffix) as input_pnm, \
-            NamedTemporaryFile(suffix=suffix, mode="r+b") as output_pnm:
-        im.save(input_pnm, format='PPM')
-        im.close()
-
-        os.unlink(output_pnm.name)
-
-        args_unpaper.extend([input_pnm.name, output_pnm.name])
-        p_unpaper = Popen(
-            args_unpaper, close_fds=True,
-            universal_newlines=True, stdout=PIPE, stderr=PIPE
-            )
-        out, err = p_unpaper.communicate()
-        log.debug(out)
-        log.debug(err)
-
-        Image.open(output_pnm.name).save(output_file)
-
-
-def deskew(input_file, output_file, dpi, log):
-    run(input_file, output_file, dpi, log, [
-        '--mask-scan-size', '100',  # don't blank out narrow columns
-        '--no-border-align',  # don't align visible content to borders
-        '--no-mask-center',   # don't center visible content within page
-        '--no-grayfilter',    # don't remove light gray areas
-        '--no-blackfilter',   # don't remove solid black areas
-        '--no-noisefilter',   # don't remove salt and pepper noise
-        '--no-blurfilter'     # don't remove blurry objects/debris
-    ])
-
-
-def clean(input_file, output_file, dpi, log):
-    run(input_file, output_file, dpi, log, [
-        '--mask-scan-size', '100',  # don't blank out narrow columns
-        '--no-border-align',  # don't align visible content to borders
-        '--no-mask-center',   # don't center visible content within page
-        '--no-grayfilter',    # don't remove light gray areas
-        '--no-blackfilter',   # don't remove solid black areas
-        '--no-deskew',        # don't deskew
-    ])

pipeline.svg

@@ -1,235 +0,0 @@
-<?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
- "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
-<!-- Generated by graphviz version 2.38.0 (20140413.2041)
- -->
-<!-- Title: Pipeline: Pages: 1 -->
-<svg width="728pt" height="651pt"
- viewBox="0.00 0.00 728.00 650.53" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
-<g id="graph0" class="graph" transform="scale(1 1) rotate(0) translate(4 646.53)">
-<title>Pipeline:</title>
-<polygon fill="white" stroke="none" points="-4,4 -4,-646.53 724,-646.53 724,4 -4,4"/>
-<g id="clust1" class="cluster"><title>clustertasks</title>
-<polygon fill="none" stroke="black" points="8,-8 8,-634.53 712,-634.53 712,-8 8,-8"/>
-<text text-anchor="middle" x="360" y="-606.53" font-family="Times,serif" font-size="30.00" fill="#ff3232">Pipeline:</text>
-</g>
-<!-- t0 -->
-<g id="node1" class="node"><title>t0</title>
-<polygon fill="#efa03b" stroke="#006000" points="481.791,-588.53 386.209,-588.53 382.209,-584.53 382.209,-552.53 477.791,-552.53 481.791,-556.53 481.791,-588.53"/>
-<polyline fill="none" stroke="#006000" points="477.791,-584.53 382.209,-584.53 "/>
-<polyline fill="none" stroke="#006000" points="477.791,-584.53 477.791,-552.53 "/>
-<polyline fill="none" stroke="#006000" points="477.791,-584.53 481.791,-588.53 "/>
-<text text-anchor="middle" x="432" y="-564.53" font-family="Times,serif" font-size="20.00" fill="#006000">repair_pdf</text>
-</g>
-<!-- t1 -->
-<g id="node2" class="node"><title>t1</title>
-<polygon fill="#efa03b" stroke="black" points="466.782,-509.564 374,-526.497 281.218,-509.564 281.304,-482.165 466.696,-482.165 466.782,-509.564"/>
-<polygon fill="none" stroke="black" points="470.799,-512.902 374,-530.569 277.201,-512.902 277.311,-478.159 470.689,-478.159 470.799,-512.902"/>
-<text text-anchor="middle" x="374" y="-495.991" font-family="Times,serif" font-size="20.00">split_pages</text>
-</g>
-<!-- t0&#45;&gt;t1 -->
-<g id="edge1" class="edge"><title>t0&#45;&gt;t1</title>
-<path fill="none" stroke="gray" d="M417.064,-552.394C412.296,-546.925 406.86,-540.689 401.493,-534.532"/>
-<polygon fill="gray" stroke="gray" points="403.996,-532.077 394.787,-526.838 398.719,-536.676 403.996,-532.077"/>
-</g>
-<!-- t10 -->
-<g id="node12" class="node"><title>t10</title>
-<polygon fill="#efa03b" stroke="#006000" points="704.338,-451.452 493.662,-451.452 489.662,-447.452 489.662,-415.452 700.338,-415.452 704.338,-419.452 704.338,-451.452"/>
-<polyline fill="none" stroke="#006000" points="700.338,-447.452 489.662,-447.452 "/>
-<polyline fill="none" stroke="#006000" points="700.338,-447.452 700.338,-415.452 "/>
-<polyline fill="none" stroke="#006000" points="700.338,-447.452 704.338,-451.452 "/>
-<text text-anchor="middle" x="597" y="-427.452" font-family="Times,serif" font-size="20.00" fill="#006000">generate_postscript_stub</text>
-</g>
-<!-- t0&#45;&gt;t10 -->
-<g id="edge16" class="edge"><title>t0&#45;&gt;t10</title>
-<path fill="none" stroke="gray" d="M453.048,-552.468C461.441,-545.654 471.185,-537.73 480,-530.53 510.227,-505.84 544.753,-477.467 568.421,-457.99"/>
-<polygon fill="gray" stroke="gray" points="570.818,-460.55 576.315,-451.493 566.369,-455.146 570.818,-460.55"/>
-</g>
-<!-- t2 -->
-<g id="node3" class="node"><title>t2</title>
-<polygon fill="#efa03b" stroke="black" points="451.555,-451.452 228.445,-451.452 224.445,-447.452 224.445,-415.452 447.555,-415.452 451.555,-419.452 451.555,-451.452"/>
-<polyline fill="none" stroke="black" points="447.555,-447.452 224.445,-447.452 "/>
-<polyline fill="none" stroke="black" points="447.555,-447.452 447.555,-415.452 "/>
-<polyline fill="none" stroke="black" points="447.555,-447.452 451.555,-451.452 "/>
-<text text-anchor="middle" x="338" y="-427.452" font-family="Times,serif" font-size="20.00">rasterize_with_ghostscript</text>
-</g>
-<!-- t1&#45;&gt;t2 -->
-<g id="edge2" class="edge"><title>t1&#45;&gt;t2</title>
-<path fill="none" stroke="#0044a0" d="M361.611,-478.092C358.514,-472.369 355.171,-466.19 352.003,-460.333"/>
-<polygon fill="#0044a0" stroke="#0044a0" points="355.064,-458.636 347.227,-451.506 348.907,-461.967 355.064,-458.636"/>
-</g>
-<!-- t11 -->
-<g id="node10" class="node"><title>t11</title>
-<polygon fill="#efa03b" stroke="black" points="644.594,-393.452 551.406,-393.452 547.406,-389.452 547.406,-357.452 640.594,-357.452 644.594,-361.452 644.594,-393.452"/>
-<polyline fill="none" stroke="black" points="640.594,-389.452 547.406,-389.452 "/>
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-<polyline fill="none" stroke="black" points="640.594,-389.452 644.594,-393.452 "/>
-<text text-anchor="middle" x="596" y="-369.452" font-family="Times,serif" font-size="20.00">skip_page</text>
-</g>
-<!-- t1&#45;&gt;t11 -->
-<g id="edge13" class="edge"><title>t1&#45;&gt;t11</title>
-<path fill="none" stroke="#0044a0" d="M425.139,-478.007C437.834,-470.731 450.731,-461.83 461,-451.452 473.874,-438.442 466.946,-427.178 481,-415.452 490.212,-407.766 513.965,-399.205 537.508,-392.067"/>
-<polygon fill="#0044a0" stroke="#0044a0" points="538.592,-395.396 547.189,-389.203 536.607,-388.683 538.592,-395.396"/>
-</g>
-<!-- t9 -->
-<g id="node11" class="node"><title>t9</title>
-<polygon fill="#efa03b" stroke="black" points="272.496,-277.452 19.5039,-277.452 15.5039,-273.452 15.5039,-241.452 268.496,-241.452 272.496,-245.452 272.496,-277.452"/>
-<polyline fill="none" stroke="black" points="268.496,-273.452 15.5039,-273.452 "/>
-<polyline fill="none" stroke="black" points="268.496,-273.452 268.496,-241.452 "/>
-<polyline fill="none" stroke="black" points="268.496,-273.452 272.496,-277.452 "/>
-<text text-anchor="middle" x="144" y="-253.452" font-family="Times,serif" font-size="20.00">tesseract_ocr_and_render_pdf</text>
-</g>
-<!-- t1&#45;&gt;t9 -->
-<g id="edge15" class="edge"><title>t1&#45;&gt;t9</title>
-<path fill="none" stroke="#0044a0" d="M277.341,-486.044C254.708,-478.702 232.21,-467.759 215,-451.452 168.207,-407.114 152.056,-329.127 146.633,-287.855"/>
-<polygon fill="#0044a0" stroke="#0044a0" points="150.084,-287.235 145.422,-277.721 143.133,-288.065 150.084,-287.235"/>
-</g>
-<!-- t3 -->
-<g id="node4" class="node"><title>t3</title>
-<polygon fill="#efa03b" stroke="black" points="458.999,-393.452 291.001,-393.452 287.001,-389.452 287.001,-357.452 454.999,-357.452 458.999,-361.452 458.999,-393.452"/>
-<polyline fill="none" stroke="black" points="454.999,-389.452 287.001,-389.452 "/>
-<polyline fill="none" stroke="black" points="454.999,-389.452 454.999,-357.452 "/>
-<polyline fill="none" stroke="black" points="454.999,-389.452 458.999,-393.452 "/>
-<text text-anchor="middle" x="373" y="-369.452" font-family="Times,serif" font-size="20.00">preprocess_deskew</text>
-</g>
-<!-- t2&#45;&gt;t3 -->
-<g id="edge3" class="edge"><title>t2&#45;&gt;t3</title>
-<path fill="none" stroke="#0044a0" d="M348.691,-415.346C351.337,-411.112 354.23,-406.485 357.066,-401.946"/>
-<polygon fill="#0044a0" stroke="#0044a0" points="360.042,-403.788 362.374,-393.453 354.106,-400.078 360.042,-403.788"/>
-</g>
-<!-- t6 -->
-<g id="node6" class="node"><title>t6</title>
-<polygon fill="#efa03b" stroke="black" points="664.375,-277.452 477.625,-277.452 473.625,-273.452 473.625,-241.452 660.375,-241.452 664.375,-245.452 664.375,-277.452"/>
-<polyline fill="none" stroke="black" points="660.375,-273.452 473.625,-273.452 "/>
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-<polyline fill="none" stroke="black" points="660.375,-273.452 664.375,-277.452 "/>
-<text text-anchor="middle" x="569" y="-253.452" font-family="Times,serif" font-size="20.00">select_image_for_pdf</text>
-</g>
-<!-- t2&#45;&gt;t6 -->
-<g id="edge7" class="edge"><title>t2&#45;&gt;t6</title>
-<path fill="none" stroke="#0044a0" d="M423.032,-415.374C438.812,-409.925 454.543,-402.785 468,-393.452 508.201,-365.571 539.287,-316.662 555.808,-286.558"/>
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-<text text-anchor="middle" x="373" y="-311.452" font-family="Times,serif" font-size="20.00">preprocess_clean</text>
-</g>
-<!-- t3&#45;&gt;t4 -->
-<g id="edge4" class="edge"><title>t3&#45;&gt;t4</title>
-<path fill="none" stroke="#0044a0" d="M373,-357.346C373,-353.655 373,-349.665 373,-345.695"/>
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-<!-- t3&#45;&gt;t6 -->
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-</g>
-<!-- t4&#45;&gt;t6 -->
-<g id="edge5" class="edge"><title>t4&#45;&gt;t6</title>
-<path fill="none" stroke="#0044a0" d="M432.605,-299.422C453.701,-293.395 477.617,-286.561 499.465,-280.319"/>
-<polygon fill="#0044a0" stroke="#0044a0" points="500.687,-283.61 509.341,-277.497 498.764,-276.879 500.687,-283.61"/>
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-</g>
-<!-- t4&#45;&gt;t5 -->
-<g id="edge8" class="edge"><title>t4&#45;&gt;t5</title>
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-<!-- t4&#45;&gt;t9 -->
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-</g>
-<!-- t6&#45;&gt;t7 -->
-<g id="edge9" class="edge"><title>t6&#45;&gt;t7</title>
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pyproject.toml

@@ -0,0 +1,80 @@
+[build-system]
+requires = [
+  "setuptools >= 30.3.0",
+  "wheel",
+  "setuptools_scm[toml] >= 3.4",
+  "setuptools_scm_git_archive"
+]
+build-backend = "setuptools.build_meta"
+
+[tool.setuptools_scm]
+version_scheme = "post-release"
+
+[tool.black]
+line-length = 88
+target-version = ["py36", "py37", "py38"]
+skip-string-normalization = true
+include = '\.pyi?$'
+exclude = '''
+/(
+    \.eggs
+  | \.git
+  | \.hg
+  | \.mypy_cache
+  | \.tox
+  | \.venv
+  | _build
+  | buck-out
+  | build
+  | dist
+  | docs
+  | misc
+  | \.egg-info
+)/
+'''
+
+[tool.coverage.run]
+branch = true
+parallel = true
+concurrency = ["multiprocessing"]
+
+[tool.coverage.paths]
+source = ["src/ocrmypdf"]
+
+[tool.coverage.report]
+# Regexes for lines to exclude from consideration
+exclude_lines = [
+    # Have to re-enable the standard pragma
+    "pragma: no cover",
+
+    # Don't complain if tests don't hit defensive assertion code:
+    "raise AssertionError",
+    "raise NotImplementedError",
+
+    # Don't complain if non-runnable code isn't run:
+    "if 0:",
+	  "if False:",
+    "if __name__ == .__main__.:",
+    "if TYPE_CHECKING:"
+]
+
+[tool.isort]
+profile = "black"
+known_first_party = "ocrmypdf"
+known_third_party = ["PIL", "flask", "img2pdf", "ocrmypdf", "pdfminer", "pikepdf", "pkg_resources", "pluggy", "pytest", "reportlab", "setuptools", "sphinx_rtd_theme", "tqdm", "watchdog", "werkzeug"]
+
+[tool.pytest.ini_options]
+minversion = "6.0"
+norecursedirs = ["lib", ".pc", ".git", "venv", "output", "cache", "resources"]
+testpaths = ["tests"]
+addopts = "-n auto"
+markers = ["slow"]
+filterwarnings = ["ignore:.*XMLParser.*:DeprecationWarning"]
+
+[tool.mypy]
+
+[[tool.mypy.overrides]]
+module = [
+  'pluggy', 'tqdm', 'coloredlogs', 'img2pdf', 'pdfminer.*', 'reportlab.*'
+]
+ignore_missing_imports = true

setup.cfg

@@ -1,2 +1,112 @@
+[metadata]
+name = ocrmypdf
+description = OCRmyPDF adds an OCR text layer to scanned PDF files, allowing them to be searched
+long_description = file: README.md
+long_description_content_type = text/markdown
+url = https://github.com/jbarlow83/OCRmyPDF
+author = James R. Barlow
+author_email = james@purplerock.ca
+license = MPL-2.0
+license_file = LICENSE
+license_files =
+    LICENSE
+classifiers =
+    Development Status :: 5 - Production/Stable
+    Environment :: Console
+    Intended Audience :: End Users/Desktop
+    Intended Audience :: Science/Research
+    Intended Audience :: System Administrators
+    License :: OSI Approved :: Mozilla Public License 2.0 (MPL 2.0)
+    Operating System :: MacOS :: MacOS X
+    Operating System :: Microsoft :: Windows :: Windows 10
+    Operating System :: POSIX
+    Operating System :: POSIX :: BSD
+    Operating System :: POSIX :: Linux
+    Programming Language :: Python :: 3
+    Programming Language :: Python :: 3 :: Only
+    Programming Language :: Python :: 3.7
+    Programming Language :: Python :: 3.8
+    Programming Language :: Python :: 3.9
+    Programming Language :: Python :: 3.10
+    Topic :: Scientific/Engineering :: Image Recognition
+    Topic :: Text Processing :: Indexing
+    Topic :: Text Processing :: Linguistic
+keywords =
+    PDF
+    OCR
+    optical character recognition
+    PDF/A
+    scanning
+project_urls =
+    Documentation = https://ocrmypdf.readthedocs.io/
+    Source = https://github.com/jbarlow83/ocrmypdf
+    Tracker = https://github.com/jbarlow83/ocrmypdf/issues
+
+[options]
+packages = find:
+install_requires =
+    Pillow>=8.2.0
+    coloredlogs>=14.0  # strictly optional
+    img2pdf>=0.3.0,<0.5  # pure Python
+    pdfminer.six!=20200720,>=20191110,<=20211012
+    pikepdf>=4.0.0
+    pluggy>=0.13.0,<2
+    reportlab>=3.5.66
+    tqdm>=4
+    importlib-metadata>=4;python_version<'3.8'  # until Python 3.8
+    importlib-resources>=5;python_version<'3.9'  # until Python 3.9
+python_requires = >=3.7
+include_package_data = True
+package_dir =
+    =src
+platforms = any
+setup_requires =
+    setuptools-scm
+    setuptools-scm-git-archive
+zip_safe = False
+
+[options.packages.find]
+where = src
+
+[options.entry_points]
+console_scripts =
+    ocrmypdf = ocrmypdf.__main__:run
+
+[options.extras_require]
+docs =
+    sphinx
+    sphinx-issues
+    sphinx-rtd-theme
+extended_test =
+    PyMuPDF==1.19.1
+test =
+    coverage[toml]>=5
+    pytest>=6.0.0
+    pytest-cov>=2.11.1
+    pytest-xdist>=2.2.0
+    python-xmp-toolkit==2.0.1  # also requires apt-get install libexempi3
+watcher =
+    watchdog>=1.0.2,<3
+webservice =
+    Flask>=1,<3
+
+[options.package_data]
+ocrmypdf =
+    data/sRGB.icc
+    py.typed
+
 [bdist_wheel]
-python-tag = py34
+python-tag = py37
+
+[aliases]
+test = pytest
+
+[check-manifest]
+ignore =
+    .github
+
+[flake8]
+ignore = D203,F401,W503,E501,E203,F841
+exclude = .git,__pycache__,docs/conf.py,build,dist,.venv,.venvpp,.eggs,tmp,src/ocrmypdf/lib/
+max-complexity = 10
+max-line-length = 100

setup.py

@@ -1,220 +1,17 @@
-#!/usr/bin/env python3
-# © 2015 James R. Barlow: github.com/jbarlow83
+# © 2021 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
 
 from setuptools import setup
-from subprocess import Popen, STDOUT, check_output, CalledProcessError
-from string import Template
-from collections.abc import Mapping
-import re
-import sys
-
-
-missing_program = '''
-The program '{program}' could not be executed or was not found on your
-system PATH.
-'''
-
-unknown_version = '''
-OCRmyPDF requires '{program}' {need_version} or higher.  Your system has
-'{program}' but we cannot tell what version is installed.  Contact the
-package maintainer.
-'''
-
-old_version = '''
-OCRmyPDF requires '{program}' {need_version} or higher.  Your system appears
-to have {found_version}.  Please update this program.
-'''
-
-okay_its_optional = '''
-This program is OPTIONAL, so installation of OCRmyPDF can proceed, but
-some functionality may be missing.
-'''
-
-not_okay_its_required = '''
-This program is REQUIRED for OCRmyPDF to work.  Installation will abort.
-'''
-
-osx_install_advice = '''
-If you have homebrew installed, try these command to install the missing
-packages:
-    brew update
-    brew upgrade
-    brew install {package}
-'''
-
-linux_install_advice = '''
-On systems with the aptitude package manager (Debian, Ubuntu), try these
-commands:
-    sudo apt-get update
-    sudo apt-get install {package}
-
-On RPM-based systems (Red Hat, Fedora), search for instructions on
-installing the RPM for {program}.
-'''
-
-
-def get_platform():
-    if sys.platform.startswith('freebsd'):
-        return 'freebsd'
-    elif sys.platform.startswith('linux'):
-        return 'linux'
-    return sys.platform
-
-
-def _error_trailer(program, package, optional, **kwargs):
-    if optional:
-        print(okay_its_optional.format(**locals()), file=sys.stderr)
-    else:
-        print(not_okay_its_required.format(**locals()), file=sys.stderr)
-
-    if isinstance(package, Mapping):
-        package = package[get_platform()]
-
-    if get_platform() == 'darwin':
-        print(osx_install_advice.format(**locals()), file=sys.stderr)
-    elif get_platform() == 'linux':
-        print(linux_install_advice.format(**locals()), file=sys.stderr)
-
-
-def error_missing_program(
-        program,
-        package,
-        optional
-        ):
-    print(missing_program.format(**locals()), file=sys.stderr)
-    _error_trailer(**locals())
-
-
-def error_unknown_version(
-        program,
-        package,
-        optional,
-        need_version
-        ):
-    print(unknown_version.format(**locals()), file=sys.stderr)
-    _error_trailer(**locals())
-
-
-def error_old_version(
-        program,
-        package,
-        optional,
-        need_version,
-        found_version
-        ):
-    print(old_version.format(**locals()), file=sys.stderr)
-    _error_trailer(**locals())
-
-
-def check_external_program(
-        program,
-        need_version,
-        package,
-        version_check_args=['--version'],
-        version_scrape_regex=re.compile(r'(\d+\.\d+(?:\.\d+)?)'),
-        optional=False):
-
-    print('Checking for {program} >= {need_version}...'.format(
-            program=program, need_version=need_version))
-    try:
-        result = check_output(
-                [program] + version_check_args,
-                universal_newlines=True, stderr=STDOUT)
-    except (CalledProcessError, FileNotFoundError):
-        error_missing_program(program, package, optional)
-        if not optional:
-            sys.exit(1)
-        print('Continuing install without {program}'.format(program=program))
-        return
-
-    try:
-        found_version = version_scrape_regex.search(result).group(1)
-    except AttributeError:
-        error_unknown_version(program, package, optional, need_version)
-        sys.exit(1)
-
-    if found_version < need_version:
-        error_old_version(program, package, optional, need_version,
-                          found_version)
-
-    print('Found {program} {found_version}'.format(
-            program=program, found_version=found_version))
-
-
-command = next((arg for arg in sys.argv[1:] if not arg.startswith('-')), '')
-
-
-if command.startswith('install') or \
-        command in ['check', 'test', 'nosetests', 'easy_install', 'egg_info']:
-    check_external_program(
-        program='tesseract',
-        need_version='3.02.02',
-        package={'darwin': 'tesseract', 'linux': 'tesseract-ocr'}
-    )
-    check_external_program(
-        program='gs',
-        need_version='9.14',
-        package='ghostscript'
-    )
-    check_external_program(
-        program='unpaper',
-        need_version='6.1',
-        package='unpaper',
-        optional=True
-    )
-    check_external_program(
-        program='qpdf',
-        need_version='5.0.0',
-        package='qpdf',
-        version_check_args=['--version']
-    )
-
-
-if 'upload' in sys.argv[1:]:
-    print('Use twine to upload the package - setup.py upload is insecure')
-    sys.exit(1)
 
+# Minimal setup to support older setuptools/setuptools_scm
 setup(
-    name='ocrmypdf',
-    version='3.0rc5',  # also update: release notes, main.py
-    description='OCRmyPDF adds an OCR text layer to scanned PDF files, allowing them to be searched',
-    url='https://github.com/fritz-hh/OCRmyPDF',
-    author='James. R. Barlow',
-    author_email='jim@purplerock.ca',
-    license='Public Domain',
-    packages=['ocrmypdf'],
-    keywords=['PDF', 'OCR', 'optical character recognition', 'PDF/A', 'scanning'],
-    classifiers=[
-        "Programming Language :: Python :: 3",
-        "Development Status :: 4 - Beta",
-        "Environment :: Console",
-        "Intended Audience :: End Users/Desktop",
-        "Intended Audience :: Science/Research",
-        "Intended Audience :: System Administrators",
-        "License :: Public Domain",
-        "Operating System :: MacOS :: MacOS X",
-        "Operating System :: POSIX",
-        "Operating System :: POSIX :: BSD",
-        "Operating System :: POSIX :: Linux",
-        "Topic :: Scientific/Engineering :: Image Recognition",
-        "Topic :: Text Processing :: Indexing",
-        "Topic :: Text Processing :: Linguistic",
-        ],
-    install_requires=[
-        'ruffus>=2.6.3',
-        'Pillow>=2.4.0',
-        'lxml>=3.3.3',
-        'reportlab>=3.1.44',
-        'PyPDF2>=1.25.1'
+    setup_requires=[  # can be removed whenever we can drop pip 9 support
+        'setuptools_scm',  # so that version will work
+        'setuptools_scm_git_archive',  # enable version from github tarballs
     ],
-    tests_require=[
-        'img2pdf>=0.1.5',
-        'pytest>=2.7.2'
-    ],
-    entry_points={
-        'console_scripts': [
-            'ocrmypdf = ocrmypdf.main:run_pipeline'
-        ],
-    },
-    include_package_data=True,
-    zip_safe=False)
+    use_scm_version={'version_scheme': 'post-release'},
+)

src/ocrmypdf/RELEASE.md

@@ -0,0 +1,35 @@
+# Release checklist
+
+## Patch release
+
+- Check `pytest`
+
+- Update release notes
+
+## Minor release
+
+## Major release
+
+- Run `pre-commit autoupdate`
+
+- Check README.md
+
+- Check setup.py
+
+    - Are classifiers up to date?
+    - Is `python_requires` correct?
+    - Python 3.6 is EOL on December 2021-12. Could drop support then.
+    - Can we tighten any `install_requires` dependencies?
+
+- Search for old version shims we can remove
+
+    - "shim"
+    - ` pikepdf.__version__`
+
+- Search for deprecation: search all files for deprec*, etc.
+
+- Check requirements in setup.cfg
+
+- Delete `tests/cache`, do `pytest --runslow`, and update cache.
+
+- Do `pytest --cov-report html`

src/ocrmypdf/__init__.py

@@ -0,0 +1,32 @@
+# © 2017 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+from pluggy import HookimplMarker as _HookimplMarker
+
+from ocrmypdf import helpers, hocrtransform, pdfa, pdfinfo
+from ocrmypdf._concurrent import Executor
+from ocrmypdf._jobcontext import PageContext, PdfContext
+from ocrmypdf._version import PROGRAM_NAME, __version__
+from ocrmypdf.api import Verbosity, configure_logging, ocr
+from ocrmypdf.exceptions import (
+    BadArgsError,
+    DpiError,
+    EncryptedPdfError,
+    ExitCode,
+    ExitCodeException,
+    InputFileError,
+    MissingDependencyError,
+    OutputFileAccessError,
+    PdfMergeFailedError,
+    PriorOcrFoundError,
+    SubprocessOutputError,
+    TesseractConfigError,
+    UnsupportedImageFormatError,
+)
+from ocrmypdf.pluginspec import OcrEngine, OrientationConfidence
+
+hookimpl = _HookimplMarker('ocrmypdf')

src/ocrmypdf/__main__.py

@@ -0,0 +1,75 @@
+#!/usr/bin/env python3
+# © 2015-19 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import logging
+import os
+import signal
+import sys
+from multiprocessing import set_start_method
+
+from ocrmypdf import __version__
+from ocrmypdf._plugin_manager import get_parser_options_plugins
+from ocrmypdf._sync import run_pipeline
+from ocrmypdf._validation import check_options
+from ocrmypdf.api import Verbosity, configure_logging
+from ocrmypdf.exceptions import (
+    BadArgsError,
+    ExitCode,
+    InputFileError,
+    MissingDependencyError,
+)
+
+log = logging.getLogger('ocrmypdf')
+
+
+def sigbus(*args):
+    raise InputFileError("Lost access to the input file")
+
+
+def run(args=None):
+    _parser, options, plugin_manager = get_parser_options_plugins(args=args)
+
+    if hasattr(os, 'nice'):
+        os.nice(5)
+
+    verbosity = options.verbose
+    if not os.isatty(sys.stderr.fileno()):
+        options.progress_bar = False
+    if options.quiet:
+        verbosity = Verbosity.quiet
+        options.progress_bar = False
+    configure_logging(
+        verbosity,
+        progress_bar_friendly=options.progress_bar,
+        manage_root_logger=True,
+        plugin_manager=plugin_manager,
+    )
+    log.debug('ocrmypdf %s', __version__)
+    try:
+        check_options(options, plugin_manager)
+    except ValueError as e:
+        log.error(e)
+        return ExitCode.bad_args
+    except BadArgsError as e:
+        log.error(e)
+        return e.exit_code
+    except MissingDependencyError as e:
+        log.error(e)
+        return ExitCode.missing_dependency
+
+    if hasattr(signal, 'SIGBUS'):
+        signal.signal(signal.SIGBUS, sigbus)
+
+    result = run_pipeline(options=options, plugin_manager=plugin_manager)
+    return result
+
+
+if __name__ == '__main__':
+    if sys.platform == 'darwin' and sys.version_info < (3, 8):
+        set_start_method('spawn')  # see python bpo-33725
+    sys.exit(run())

src/ocrmypdf/_concurrent.py

@@ -0,0 +1,133 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import threading
+from abc import ABC, abstractmethod
+from typing import Callable, Iterable, Optional
+
+
+def _task_noop(*_args, **_kwargs):
+    return
+
+
+class NullProgressBar:
+    def __init__(self, **kwargs):
+        pass
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        return False
+
+    def update(self, _arg=None):
+        return
+
+
+class Executor(ABC):
+    pool_lock = threading.Lock()
+    pbar_class = NullProgressBar
+
+    def __init__(self, *, pbar_class=None):
+        if pbar_class:
+            self.pbar_class = pbar_class
+
+    def __call__(
+        self,
+        *,
+        use_threads: bool,
+        max_workers: int,
+        tqdm_kwargs: dict,
+        worker_initializer: Optional[Callable] = None,
+        task: Optional[Callable] = None,
+        task_arguments: Optional[Iterable] = None,
+        task_finished: Optional[Callable] = None,
+    ) -> None:
+        """
+        Set up parallel execution and progress reporting.
+
+        Args:
+            use_threads: If ``False``, the workload is the sort that will benefit from
+                running in a multiprocessing context (for example, it uses Python
+                heavily, and parallelizing it with threads is not expected to be
+                performant).
+            max_workers: The maximum number of workers that should be run.
+            tdqm_kwargs: Arguments to set up the progress bar.
+            worker_initializer: Called when a worker is initialized, in the worker's
+                execution context. If the child workers are processes, it must be
+                possible to marshall/pickle the worker initializer.
+                ``functools.partial`` can be used to bind parameters.
+            task: Called when the worker starts a new task, in the worker's execution
+                context. Must be possible to marshall to the worker.
+            task_finished: Called when a worker finishes a task, in the parent's
+                context.
+            task_arguments: An iterable that generates a group of parameters for each
+                task. This runs in the parent's context, but the parameters must be
+                marshallable to the worker.
+        """
+
+        if not task_arguments:
+            return  # Nothing to do!
+        if not worker_initializer:
+            worker_initializer = _task_noop
+        if not task_finished:
+            task_finished = _task_noop
+        if not task:
+            task = _task_noop
+
+        with self.pool_lock:
+            self._execute(
+                use_threads=use_threads,
+                max_workers=max_workers,
+                tqdm_kwargs=tqdm_kwargs,
+                worker_initializer=worker_initializer,
+                task=task,
+                task_arguments=task_arguments,
+                task_finished=task_finished,
+            )
+
+    @abstractmethod
+    def _execute(
+        self,
+        *,
+        use_threads: bool,
+        max_workers: int,
+        tqdm_kwargs: dict,
+        worker_initializer: Callable,
+        task: Callable,
+        task_arguments: Iterable,
+        task_finished: Callable,
+    ):
+        """Custom executors should override this method."""
+
+
+def setup_executor(plugin_manager) -> Executor:
+    pbar_class = plugin_manager.hook.get_progressbar_class()
+    return plugin_manager.hook.get_executor(progressbar_class=pbar_class)
+
+
+class SerialExecutor(Executor):
+    """Implements a purely sequential executor using the parallel protocol.
+
+    The current process/thread will be the worker that executes all tasks
+    in order. As such, ``worker_initializer`` will never be called.
+    """
+
+    def _execute(
+        self,
+        *,
+        use_threads: bool,
+        max_workers: int,
+        tqdm_kwargs: dict,
+        worker_initializer: Callable,
+        task: Callable,
+        task_arguments: Iterable,
+        task_finished: Callable,
+    ):  # pylint: disable=unused-argument
+        with self.pbar_class(**tqdm_kwargs) as pbar:
+            for args in task_arguments:
+                result = task(args)
+                task_finished(result, pbar)

src/ocrmypdf/_exec/__init__.py

@@ -0,0 +1,8 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+"""Manage third party executables"""

src/ocrmypdf/_exec/ghostscript.py

@@ -0,0 +1,272 @@
+# © 2017 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+"""Interface to Ghostscript executable"""
+
+import logging
+import os
+import re
+import sys
+from io import BytesIO
+from os import fspath
+from pathlib import Path
+from shutil import which
+from subprocess import PIPE, CalledProcessError
+from typing import Optional
+
+from PIL import Image
+
+from ocrmypdf.exceptions import MissingDependencyError, SubprocessOutputError
+from ocrmypdf.helpers import Resolution
+from ocrmypdf.subprocess import get_version, run, run_polling_stderr
+
+log = logging.getLogger(__name__)
+
+missing_gs_error = """
+---------------------------------------------------------------------
+This error normally occurs when ocrmypdf find can't Ghostscript.
+Please ensure Ghostscript is installed and its location is added to
+the system PATH environment variable.
+
+For details see:
+    https://ocrmypdf.readthedocs.io/en/latest/installation.html
+---------------------------------------------------------------------
+"""
+
+# Most reliable what to get the bitness of Python interpreter, according to Python docs
+_is_64bit = sys.maxsize > 2 ** 32
+
+_gswin = None
+if os.name == 'nt':
+    if _is_64bit:
+        _gswin = 'gswin64c'
+    else:
+        _gswin = 'gswin32c'
+
+GS = _gswin if _gswin else 'gs'
+del _gswin
+
+
+def version():
+    return get_version(GS)
+
+
+def jpeg_passthrough_available() -> bool:
+    """Returns True if the installed version of Ghostscript supports JPEG passthru
+
+    Prior to 9.23, Ghostscript decoded and re-encoded JPEGs internally. In 9.23
+    it gained the ability to keep JPEGs unmodified. However, the 9.23
+    implementation was buggy and would deletes the last two bytes of images in
+    some cases, as reported here.
+    https://bugs.ghostscript.com/show_bug.cgi?id=699216
+
+    The issue was fixed for 9.24, hence that is the first version we consider
+    the feature available. (Ghostscript 9.24 has its own problems is blacklisted.)
+    """
+    return version() >= '9.24'
+
+
+def _gs_error_reported(stream) -> bool:
+    return True if re.search(r'error', stream, flags=re.IGNORECASE) else False
+
+
+def rasterize_pdf(
+    input_file: os.PathLike,
+    output_file: os.PathLike,
+    *,
+    raster_device: str,
+    raster_dpi: Resolution,
+    pageno: int = 1,
+    page_dpi: Optional[Resolution] = None,
+    rotation: Optional[int] = None,
+    filter_vector: bool = False,
+):
+    """Rasterize one page of a PDF at resolution raster_dpi in canvas units."""
+    raster_dpi = raster_dpi.round(6)
+    if not page_dpi:
+        page_dpi = raster_dpi
+
+    args_gs = (
+        [
+            GS,
+            '-dQUIET',
+            '-dSAFER',
+            '-dBATCH',
+            '-dNOPAUSE',
+            f'-sDEVICE={raster_device}',
+            f'-dFirstPage={pageno}',
+            f'-dLastPage={pageno}',
+            f'-r{raster_dpi.x:f}x{raster_dpi.y:f}',
+        ]
+        + (['-dFILTERVECTOR'] if filter_vector else [])
+        + [
+            '-o',
+            '-',
+            '-sstdout=%stderr',
+            '-dAutoRotatePages=/None',  # Probably has no effect on raster
+            '-f',
+            fspath(input_file),
+        ]
+    )
+
+    try:
+        p = run(args_gs, stdout=PIPE, stderr=PIPE, check=True)
+    except CalledProcessError as e:
+        log.error(e.stderr.decode(errors='replace'))
+        raise SubprocessOutputError('Ghostscript rasterizing failed')
+    else:
+        stderr = p.stderr.decode(errors='replace')
+        if _gs_error_reported(stderr):
+            log.error(stderr)
+
+    with Image.open(BytesIO(p.stdout)) as im:
+        if rotation is not None:
+            log.debug("Rotating output by %i", rotation)
+            # rotation is a clockwise angle and Image.ROTATE_* is
+            # counterclockwise so this cancels out the rotation
+            if rotation == 90:
+                im = im.transpose(Image.ROTATE_90)
+            elif rotation == 180:
+                im = im.transpose(Image.ROTATE_180)
+            elif rotation == 270:
+                im = im.transpose(Image.ROTATE_270)
+            if rotation % 180 == 90:
+                page_dpi = page_dpi.flip_axis()
+        im.save(fspath(output_file), dpi=page_dpi)
+
+
+class GhostscriptFollower:
+    re_process = re.compile(r"Processing pages \d+ through (\d+).")
+    re_page = re.compile(r"Page (\d+)")
+
+    def __init__(self, progressbar_class):
+        self.count = 0
+        self.progressbar_class = progressbar_class
+        self.progressbar = None
+
+    def __call__(self, line):
+        if not self.progressbar_class:
+            return
+        if not self.progressbar:
+            m = self.re_process.match(line.strip())
+            if m:
+                self.count = int(m.group(1))
+                self.progressbar = self.progressbar_class(
+                    total=self.count, desc="PDF/A conversion", unit='page'
+                )
+                return
+        else:
+            m = self.re_page.match(line.strip())
+            if m:
+                self.progressbar.update()
+
+
+def generate_pdfa(
+    pdf_pages,
+    output_file: os.PathLike,
+    *,
+    compression: str,
+    pdf_version: str = '1.5',
+    pdfa_part: str = '2',
+    progressbar_class=None,
+):
+    # Ghostscript's compression is all or nothing. We can either force all images
+    # to JPEG, force all to Flate/PNG, or let it decide how to encode the images.
+    # In most case it's best to let it decide.
+    compression_args = []
+    if compression == 'jpeg':
+        compression_args = [
+            "-dAutoFilterColorImages=false",
+            "-dColorImageFilter=/DCTEncode",
+            "-dAutoFilterGrayImages=false",
+            "-dGrayImageFilter=/DCTEncode",
+        ]
+    elif compression == 'lossless':
+        compression_args = [
+            "-dAutoFilterColorImages=false",
+            "-dColorImageFilter=/FlateEncode",
+            "-dAutoFilterGrayImages=false",
+            "-dGrayImageFilter=/FlateEncode",
+        ]
+    else:
+        compression_args = [
+            "-dAutoFilterColorImages=true",
+            "-dAutoFilterGrayImages=true",
+        ]
+
+    strategy = 'LeaveColorUnchanged'
+    # Older versions of Ghostscript expect a leading slash in
+    # sColorConversionStrategy, newer ones should not have it. See Ghostscript
+    # git commit fe1c025d.
+    strategy = ('/' + strategy) if version() < '9.19' else strategy
+
+    if version() == '9.23':
+        # 9.23: added JPEG passthrough as a new feature, but with a bug that
+        # incorrectly formats some images. Fixed as of 9.24. So we disable this
+        # feature for 9.23.
+        # https://bugs.ghostscript.com/show_bug.cgi?id=699216
+        compression_args.append('-dPassThroughJPEGImages=false')
+
+    # nb no need to specify ProcessColorModel when ColorConversionStrategy
+    # is set; see:
+    # https://bugs.ghostscript.com/show_bug.cgi?id=699392
+    args_gs = (
+        [
+            GS,
+            "-dBATCH",
+            "-dNOPAUSE",
+            "-dSAFER",
+            "-dCompatibilityLevel=" + str(pdf_version),
+            "-sDEVICE=pdfwrite",
+            "-dAutoRotatePages=/None",
+            "-sColorConversionStrategy=" + strategy,
+        ]
+        + compression_args
+        + [
+            "-dJPEGQ=95",
+            "-dPDFA=" + pdfa_part,
+            "-dPDFACompatibilityPolicy=1",
+            "-o",
+            "-",
+            "-sstdout=%stderr",
+        ]
+    )
+    args_gs.extend(fspath(s) for s in pdf_pages)  # Stringify Path objs
+
+    try:
+        with Path(output_file).open('wb') as output:
+            p = run_polling_stderr(
+                args_gs,
+                stdout=output,
+                stderr=PIPE,
+                check=True,
+                text=True,
+                encoding='utf-8',
+                errors='replace',
+                callback=GhostscriptFollower(progressbar_class),
+            )
+    except CalledProcessError as e:
+        # Ghostscript does not change return code when it fails to create
+        # PDF/A - check PDF/A status elsewhere
+        log.error(e.stderr)
+        raise SubprocessOutputError('Ghostscript PDF/A rendering failed') from e
+    else:
+        stderr = p.stderr
+        # If there is an error we log the whole stderr, except for filtering
+        # duplicates.
+        if _gs_error_reported(stderr):
+            last_part = None
+            repcount = 0
+            for part in stderr.split('****'):
+                if part != last_part:
+                    if repcount > 1:
+                        log.error(f"(previous error message repeated {repcount} times)")
+                        repcount = 0
+                    log.error(part)
+                else:
+                    repcount += 1
+                last_part = part

src/ocrmypdf/_exec/jbig2enc.py

@@ -0,0 +1,57 @@
+# © 2018 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+"""Interface to jbig2 executable"""
+
+from subprocess import PIPE
+
+from ocrmypdf.exceptions import MissingDependencyError
+from ocrmypdf.subprocess import get_version, run
+
+
+def version():
+    return get_version('jbig2', regex=r'jbig2enc (\d+(\.\d+)*).*')
+
+
+def available():
+    try:
+        version()
+    except MissingDependencyError:
+        return False
+    return True
+
+
+def convert_group(*, cwd, infiles, out_prefix):
+    args = [
+        'jbig2',
+        '-b',
+        out_prefix,
+        '-s',  # symbol mode (lossy)
+        # '-r', # refinement mode (lossless symbol mode, currently disabled in
+        # jbig2)
+        '-p',
+    ]
+    args.extend(infiles)
+    proc = run(args, cwd=cwd, stdout=PIPE, stderr=PIPE)
+    proc.check_returncode()
+    return proc
+
+
+def convert_group_mp(args):
+    return convert_group(cwd=args[0], infiles=args[1], out_prefix=args[2])
+
+
+def convert_single(*, cwd, infile, outfile):
+    args = ['jbig2', '-p', infile]
+    with open(outfile, 'wb') as fstdout:
+        proc = run(args, cwd=cwd, stdout=fstdout, stderr=PIPE)
+    proc.check_returncode()
+    return proc
+
+
+def convert_single_mp(args):
+    return convert_single(cwd=args[0], infile=args[1], outfile=args[2])

src/ocrmypdf/_exec/pngquant.py

@@ -0,0 +1,65 @@
+# © 2018 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+"""Interface to pngquant executable"""
+
+from contextlib import contextmanager
+from io import BytesIO
+from pathlib import Path
+from subprocess import PIPE
+
+from PIL import Image
+
+from ocrmypdf.exceptions import MissingDependencyError
+from ocrmypdf.subprocess import get_version, run
+
+
+def version():
+    return get_version('pngquant', regex=r'(\d+(\.\d+)*).*')
+
+
+def available():
+    try:
+        version()
+    except MissingDependencyError:
+        return False
+    return True
+
+
+@contextmanager
+def input_as_png(input_file: Path):
+    if not input_file.name.endswith('.png'):
+        with Image.open(input_file) as im:
+            bio = BytesIO()
+            im.save(bio, format='png')
+            bio.seek(0)
+            yield bio
+    else:
+        with open(input_file, 'rb') as f:
+            yield f
+
+
+def quantize(input_file: Path, output_file: Path, quality_min: int, quality_max: int):
+    with input_as_png(input_file) as input_stream:
+        args = [
+            'pngquant',
+            '--force',
+            '--skip-if-larger',
+            '--quality',
+            f'{quality_min}-{quality_max}',
+            '--',  # pngquant: stop processing arguments
+            '-',  # pngquant: stream input and output
+        ]
+        result = run(args, stdin=input_stream, stdout=PIPE, stderr=PIPE, check=False)
+
+    if result.returncode == 0:
+        # input_file could be the same as output_file, so we defer the write
+        output_file.write_bytes(result.stdout)
+
+
+def quantize_mp(args):
+    return quantize(*args)

src/ocrmypdf/_exec/tesseract.py

@@ -0,0 +1,378 @@
+# © 2017 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+"""Interface to Tesseract executable"""
+
+import logging
+import re
+from distutils.version import StrictVersion
+from math import pi
+from os import fspath
+from pathlib import Path
+from subprocess import PIPE, STDOUT, CalledProcessError, TimeoutExpired
+from typing import Dict, Iterator, List, Optional
+
+from PIL import Image
+
+from ocrmypdf.exceptions import (
+    MissingDependencyError,
+    SubprocessOutputError,
+    TesseractConfigError,
+)
+from ocrmypdf.pluginspec import OrientationConfidence
+from ocrmypdf.subprocess import get_version, run
+
+log = logging.getLogger(__name__)
+
+
+HOCR_TEMPLATE = """<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
+    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
+ <head>
+  <title></title>
+<meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
+  <meta name='ocr-system' content='tesseract 4.0.0' />
+  <meta name='ocr-capabilities' content='ocr_page ocr_carea ocr_par ocr_line ocrx_word ocrp_wconf'/>
+</head>
+<body>
+  <div class='ocr_page' id='page_1' title='image "_blank.png"; bbox 0 0 {0} {1}; ppageno 0'>
+  </div>
+ </body>
+</html>
+"""
+
+
+class TesseractLoggerAdapter(logging.LoggerAdapter):
+    def process(self, msg, kwargs):
+        kwargs['extra'] = self.extra
+        return '[tesseract] %s' % (msg), kwargs
+
+
+class TesseractVersion(StrictVersion):
+
+    version_re = re.compile(
+        r'''
+        ^(\d+) \. (\d+) (\. (\d+))?  # groups: 1/major, 2/minor, 3/[skip], 4/patch
+        [-]?  # optional hyphen separator
+        (?: ((?:alpha|beta|rc|dev)\d*)? [.\-\ ]? (\d+)? )?  # 5/prerelease, 6/prerelease_num
+        (?:(?:-\d+)?-g[0-9a-f]+)?  # untagged git version
+        $
+        ''',
+        re.VERBOSE | re.ASCII,
+    )
+
+    def parse(self, vstring):
+        try:
+            super().parse(vstring)
+        except TypeError as e:
+            if 'int() argument must be a string' in str(e):
+                super().parse(vstring + '-0')
+
+
+def version() -> str:
+    return get_version('tesseract', regex=r'tesseract\s(.+)')
+
+
+def has_user_words():
+    """Does Tesseract have --user-words capability?
+
+    Not available in 4.0, but available in 4.1. Also available in 3.x, but
+    we no longer support 3.x.
+    """
+    return version() >= '4.1'
+
+
+def get_languages():
+    def lang_error(output):
+        msg = (
+            "Tesseract failed to report available languages.\n"
+            "Output from Tesseract:\n"
+            "-----------\n"
+        )
+        msg += output
+        return msg
+
+    args_tess = ['tesseract', '--list-langs']
+    try:
+        proc = run(
+            args_tess,
+            text=True,
+            stdout=PIPE,
+            stderr=STDOUT,
+            logs_errors_to_stdout=True,
+            check=True,
+        )
+        output = proc.stdout
+    except CalledProcessError as e:
+        raise MissingDependencyError(lang_error(e.output)) from e
+
+    for line in output.splitlines():
+        if line.startswith('Error'):
+            raise MissingDependencyError(lang_error(output))
+    _header, *rest = output.splitlines()
+    return {lang.strip() for lang in rest}
+
+
+def tess_base_args(langs: List[str], engine_mode: Optional[int]) -> List[str]:
+    args = ['tesseract']
+    if langs:
+        args.extend(['-l', '+'.join(langs)])
+    if engine_mode is not None:
+        args.extend(['--oem', str(engine_mode)])
+    return args
+
+
+def _parse_tesseract_output(binary_output: bytes) -> Dict[str, str]:
+    def g():
+        for line in binary_output.decode().splitlines():
+            line = line.strip()
+            parts = line.split(':', maxsplit=2)
+            if len(parts) == 2:
+                yield parts[0].strip(), parts[1].strip()
+
+    return {k: v for k, v in g()}
+
+
+def get_orientation(
+    input_file: Path, engine_mode: Optional[int], timeout: float
+) -> OrientationConfidence:
+    args_tesseract = tess_base_args(['osd'], engine_mode) + [
+        '--psm',
+        '0',
+        fspath(input_file),
+        'stdout',
+    ]
+
+    try:
+        p = run(args_tesseract, stdout=PIPE, stderr=STDOUT, timeout=timeout, check=True)
+    except TimeoutExpired:
+        return OrientationConfidence(angle=0, confidence=0.0)
+    except CalledProcessError as e:
+        tesseract_log_output(e.stdout)
+        tesseract_log_output(e.stderr)
+        if (
+            b'Too few characters. Skipping this page' in e.output
+            or b'Image too large' in e.output
+        ):
+            return OrientationConfidence(0, 0)
+        raise SubprocessOutputError() from e
+
+    osd = _parse_tesseract_output(p.stdout)
+    angle = int(osd.get('Orientation in degrees', 0))
+    oc = OrientationConfidence(
+        angle=angle, confidence=float(osd.get('Orientation confidence', 0))
+    )
+    return oc
+
+
+def get_deskew(
+    input_file: Path, languages: List[str], engine_mode: Optional[int], timeout: float
+) -> float:
+    """Gets angle to deskew this page, in degrees."""
+    args_tesseract = tess_base_args(languages, engine_mode) + [
+        '--psm',
+        '2',
+        fspath(input_file),
+        'stdout',
+    ]
+
+    try:
+        p = run(args_tesseract, stdout=PIPE, stderr=STDOUT, timeout=timeout, check=True)
+    except TimeoutExpired:
+        return 0.0
+    except CalledProcessError as e:
+        tesseract_log_output(e.stdout)
+        tesseract_log_output(e.stderr)
+        if b'Empty page!!' in e.output:  # Not enough info for a skew angle
+            return 0.0
+
+        raise SubprocessOutputError() from e
+
+    parsed = _parse_tesseract_output(p.stdout)
+    deskew_radians = float(parsed.get('Deskew angle', 0))
+    deskew_degrees = 180 / pi * deskew_radians
+    return deskew_degrees
+
+
+def tesseract_log_output(stream):
+    tlog = TesseractLoggerAdapter(
+        log, extra=log.extra if hasattr(log, 'extra') else None
+    )
+
+    if not stream:
+        return
+    try:
+        text = stream.decode()
+    except UnicodeDecodeError:
+        text = stream.decode('utf-8', 'ignore')
+
+    lines = text.splitlines()
+    for line in lines:
+        if line.startswith("Tesseract Open Source"):
+            continue
+        elif line.startswith("Warning in pixReadMem"):
+            continue
+        elif 'diacritics' in line:
+            tlog.warning("lots of diacritics - possibly poor OCR")
+        elif line.startswith('OSD: Weak margin'):
+            tlog.warning("unsure about page orientation")
+        elif 'Error in pixScanForForeground' in line:
+            pass  # Appears to be spurious/problem with nonwhite borders
+        elif 'Error in boxClipToRectangle' in line:
+            pass  # Always appears with pixScanForForeground message
+        elif 'parameter not found: ' in line.lower():
+            tlog.error(line.strip())
+            problem = line.split('found: ')[1]
+            raise TesseractConfigError(problem)
+        elif 'error' in line.lower() or 'exception' in line.lower():
+            tlog.error(line.strip())
+        elif 'warning' in line.lower():
+            tlog.warning(line.strip())
+        elif 'read_params_file' in line.lower():
+            tlog.error(line.strip())
+        else:
+            tlog.info(line.strip())
+
+
+def page_timedout(timeout):
+    if timeout == 0:
+        return
+    log.warning("[tesseract] took too long to OCR - skipping")
+
+
+def _generate_null_hocr(output_hocr, output_text, image):
+    """Produce a .hocr file that reports no text detected on a page that is
+    the same size as the input image."""
+    with Image.open(image) as im:
+        w, h = im.size
+
+    output_hocr.write_text(HOCR_TEMPLATE.format(w, h), encoding='utf-8')
+    output_text.write_text('[skipped page]', encoding='utf-8')
+
+
+def generate_hocr(
+    *,
+    input_file: Path,
+    output_hocr: Path,
+    output_text: Path,
+    languages: List[str],
+    engine_mode: int,
+    tessconfig: List[str],
+    timeout: float,
+    pagesegmode: int,
+    user_words,
+    user_patterns,
+):
+    prefix = output_hocr.with_suffix('')
+
+    args_tesseract = tess_base_args(languages, engine_mode)
+
+    if pagesegmode is not None:
+        args_tesseract.extend(['--psm', str(pagesegmode)])
+
+    if user_words:
+        args_tesseract.extend(['--user-words', user_words])
+
+    if user_patterns:
+        args_tesseract.extend(['--user-patterns', user_patterns])
+
+    # Reminder: test suite tesseract test plugins will break after any changes
+    # to the number of order parameters here
+    args_tesseract.extend([fspath(input_file), fspath(prefix), 'hocr', 'txt'])
+    args_tesseract.extend(tessconfig)
+    try:
+        p = run(args_tesseract, stdout=PIPE, stderr=STDOUT, timeout=timeout, check=True)
+        stdout = p.stdout
+    except TimeoutExpired:
+        # Generate a HOCR file with no recognized text if tesseract times out
+        # Temporary workaround to hocrTransform not being able to function if
+        # it does not have a valid hOCR file.
+        page_timedout(timeout)
+        _generate_null_hocr(output_hocr, output_text, input_file)
+    except CalledProcessError as e:
+        tesseract_log_output(e.output)
+        if b'Image too large' in e.output:
+            _generate_null_hocr(output_hocr, output_text, input_file)
+            return
+
+        raise SubprocessOutputError() from e
+    else:
+        tesseract_log_output(stdout)
+        # The sidecar text file will get the suffix .txt; rename it to
+        # whatever caller wants it named
+        if prefix.with_suffix('.txt').exists():
+            prefix.with_suffix('.txt').replace(output_text)
+
+
+def use_skip_page(output_pdf, output_text):
+    output_text.write_text('[skipped page]', encoding='utf-8')
+
+    # A 0 byte file to the output to indicate a skip
+    output_pdf.write_bytes(b'')
+
+
+def generate_pdf(
+    *,
+    input_file: Path,
+    output_pdf: Path,
+    output_text: Path,
+    languages: List[str],
+    engine_mode: int,
+    tessconfig: List[str],
+    timeout: float,
+    pagesegmode: int,
+    user_words,
+    user_patterns,
+):
+    """Use Tesseract to render a PDF.
+
+    input_file -- image to analyze
+    output_pdf -- file to generate
+    output_text -- OCR text file
+    languages -- list of languages to consider
+    engine_mode -- engine mode argument for tess v4
+    tessconfig -- tesseract configuration
+    timeout -- timeout (seconds)
+    """
+
+    args_tesseract = tess_base_args(languages, engine_mode)
+
+    if pagesegmode is not None:
+        args_tesseract.extend(['--psm', str(pagesegmode)])
+
+    args_tesseract.extend(['-c', 'textonly_pdf=1'])
+
+    if user_words:
+        args_tesseract.extend(['--user-words', user_words])
+
+    if user_patterns:
+        args_tesseract.extend(['--user-patterns', user_patterns])
+
+    prefix = output_pdf.parent / Path(output_pdf.stem)
+
+    # Reminder: test suite tesseract test plugins might break after any changes
+    # to the number of order parameters here
+
+    args_tesseract.extend([fspath(input_file), fspath(prefix), 'pdf', 'txt'])
+    args_tesseract.extend(tessconfig)
+    try:
+        p = run(args_tesseract, stdout=PIPE, stderr=STDOUT, timeout=timeout, check=True)
+        stdout = p.stdout
+        if prefix.with_suffix('.txt').exists():
+            prefix.with_suffix('.txt').replace(output_text)
+    except TimeoutExpired:
+        page_timedout(timeout)
+        use_skip_page(output_pdf, output_text)
+    except CalledProcessError as e:
+        tesseract_log_output(e.output)
+        if b'Image too large' in e.output:
+            use_skip_page(output_pdf, output_text)
+            return
+        raise SubprocessOutputError() from e
+    else:
+        tesseract_log_output(stdout)

src/ocrmypdf/_exec/unpaper.py

@@ -0,0 +1,134 @@
+# © 2015 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+# unpaper documentation:
+# https://github.com/Flameeyes/unpaper/blob/master/doc/basic-concepts.md
+
+"""Interface to unpaper executable"""
+
+import logging
+import os
+import shlex
+from decimal import Decimal
+from pathlib import Path
+from subprocess import PIPE, STDOUT
+from tempfile import TemporaryDirectory
+from typing import List, Optional, Tuple, Union
+
+from PIL import Image
+
+from ocrmypdf.exceptions import MissingDependencyError, SubprocessOutputError
+from ocrmypdf.subprocess import get_version
+from ocrmypdf.subprocess import run as external_run
+
+DecFloat = Union[Decimal, float]
+
+log = logging.getLogger(__name__)
+
+
+def version() -> str:
+    return get_version('unpaper')
+
+
+def _setup_unpaper_io(tmpdir: Path, input_file: Path) -> Tuple[Path, Path]:
+    SUFFIXES = {'1': '.pbm', 'L': '.pgm', 'RGB': '.ppm'}
+    with Image.open(input_file) as im:
+        im_modified = False
+        if im.mode not in SUFFIXES:
+            log.info("Converting image to other colorspace")
+            try:
+                if im.mode == 'P' and len(im.getcolors()) == 2:
+                    im = im.convert(mode='1')
+                else:
+                    im = im.convert(mode='RGB')
+            except OSError as e:
+                raise MissingDependencyError(
+                    "Could not convert image with type " + im.mode
+                ) from e
+            else:
+                im_modified = True
+        try:
+            suffix = SUFFIXES[im.mode]
+        except KeyError:
+            raise MissingDependencyError(
+                "Failed to convert image to a supported format."
+            ) from None
+
+        if im_modified or input_file.suffix != '.pnm':
+            input_pnm = tmpdir / 'input.pnm'
+            im.save(input_pnm, format='PPM')
+        else:
+            # No changes, PNG input, just use the file we already have
+            input_pnm = input_file
+        output_pnm = tmpdir / f'output{suffix}'
+    return input_pnm, output_pnm
+
+
+def run(
+    input_file: Path, output_file: Path, *, dpi: DecFloat, mode_args: List[str]
+) -> None:
+    args_unpaper = ['unpaper', '-v', '--dpi', str(round(dpi, 6))] + mode_args
+
+    with TemporaryDirectory() as tmpdir:
+        input_pnm, output_pnm = _setup_unpaper_io(Path(tmpdir), input_file)
+
+        # To prevent any shenanigans from accepting arbitrary parameters in
+        # --unpaper-args, we:
+        # 1) run with cwd set to a tmpdir with only unpaper's files
+        # 2) forbid the use of '/' in arguments, to prevent changing paths
+        # 3) append absolute paths for the input and output file
+        # This should ensure that a user cannot clobber some other file with
+        # their unpaper arguments (whether intentionally or otherwise)
+        args_unpaper.extend([os.fspath(input_pnm), os.fspath(output_pnm)])
+        external_run(
+            args_unpaper,
+            close_fds=True,
+            check=True,
+            stderr=STDOUT,  # unpaper writes logging output to stdout and stderr
+            stdout=PIPE,  # and cannot send file output to stdout
+            cwd=tmpdir,
+            logs_errors_to_stdout=True,
+        )
+        try:
+            with Image.open(output_pnm) as imout:
+                imout.save(output_file, dpi=(dpi, dpi))
+        except OSError as e:
+            raise SubprocessOutputError(
+                "unpaper: failed to produce the expected output file. "
+                + " Called with: "
+                + str(args_unpaper)
+            ) from e
+
+
+def validate_custom_args(args: str) -> List[str]:
+    unpaper_args = shlex.split(args)
+    if any(('/' in arg or arg == '.' or arg == '..') for arg in unpaper_args):
+        raise ValueError('No filenames allowed in --unpaper-args')
+    return unpaper_args
+
+
+def clean(
+    input_file: Path,
+    output_file: Path,
+    *,
+    dpi: DecFloat,
+    unpaper_args: Optional[List[str]] = None,
+):
+    default_args = [
+        '--layout',
+        'none',
+        '--mask-scan-size',
+        '100',  # don't blank out narrow columns
+        '--no-border-align',  # don't align visible content to borders
+        '--no-mask-center',  # don't center visible content within page
+        '--no-grayfilter',  # don't remove light gray areas
+        '--no-blackfilter',  # don't remove solid black areas
+        '--no-deskew',  # don't deskew
+    ]
+    if not unpaper_args:
+        unpaper_args = default_args
+    run(input_file, output_file, dpi=dpi, mode_args=unpaper_args)

src/ocrmypdf/_graft.py

@@ -0,0 +1,308 @@
+# © 2018 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import logging
+import uuid
+from contextlib import suppress
+from pathlib import Path
+from typing import Optional
+
+from pikepdf import (
+    Dictionary,
+    Name,
+    Object,
+    Operator,
+    Page,
+    Pdf,
+    PdfError,
+    PdfMatrix,
+    Stream,
+    parse_content_stream,
+    unparse_content_stream,
+)
+
+log = logging.getLogger(__name__)
+MAX_REPLACE_PAGES = 100
+
+
+def _ensure_dictionary(obj, name):
+    if name not in obj:
+        obj[name] = Dictionary({})
+    return obj[name]
+
+
+def _update_resources(*, obj, font, font_key, procset):
+    """Update this obj's fonts with a reference to the Glyphless font.
+
+    obj can be a page or Form XObject.
+    """
+
+    resources = _ensure_dictionary(obj, Name.Resources)
+    fonts = _ensure_dictionary(resources, Name.Font)
+    if font_key is not None and font_key not in fonts:
+        fonts[font_key] = font
+
+    # Reassign /ProcSet to one that just lists everything - ProcSet is
+    # obsolete and doesn't matter but recommended for old viewer support
+    if procset:
+        resources['/ProcSet'] = procset
+
+
+def strip_invisible_text(pdf, page):
+    stream = []
+    in_text_obj = False
+    render_mode = 0
+    text_objects = []
+
+    for operands, operator in parse_content_stream(page, ''):
+        if not in_text_obj:
+            if operator == Operator('BT'):
+                in_text_obj = True
+                render_mode = 0
+                text_objects.append((operands, operator))
+            else:
+                stream.append((operands, operator))
+        else:
+            if operator == Operator('Tr'):
+                render_mode = operands[0]
+            text_objects.append((operands, operator))
+            if operator == Operator('ET'):
+                in_text_obj = False
+                if render_mode != 3:
+                    stream.extend(text_objects)
+                text_objects.clear()
+
+    content_stream = unparse_content_stream(stream)
+    page.Contents = Stream(pdf, content_stream)
+
+
+class OcrGrafter:
+    def __init__(self, context):
+        self.context = context
+        self.path_base = context.origin
+
+        self.pdf_base = Pdf.open(self.path_base)
+        self.font, self.font_key = None, None
+
+        self.pdfinfo = context.pdfinfo
+        self.output_file = context.get_path('graft_layers.pdf')
+
+        self.procset = self.pdf_base.make_indirect(
+            Object.parse(b'[ /PDF /Text /ImageB /ImageC /ImageI ]')
+        )
+
+        self.emplacements = 1
+        self.interim_count = 0
+
+    def graft_page(
+        self,
+        *,
+        pageno: int,
+        image: Optional[Path],
+        textpdf: Optional[Path],
+        autorotate_correction: int,
+    ):
+        if textpdf and not self.font:
+            self.font, self.font_key = self._find_font(textpdf)
+
+        emplaced_page = False
+        content_rotation = self.pdfinfo[pageno].rotation
+        path_image = Path(image).resolve() if image else None
+        if path_image is not None and path_image != self.path_base:
+            # We are updating the old page with a rasterized PDF of the new
+            # page (without changing objgen, to preserve references)
+            log.debug("Emplacement update")
+            with Pdf.open(path_image) as pdf_image:
+                self.emplacements += 1
+                foreign_image_page = pdf_image.pages[0]
+                self.pdf_base.pages.append(foreign_image_page)
+                local_image_page = self.pdf_base.pages[-1]
+                self.pdf_base.pages[pageno].emplace(local_image_page)
+                del self.pdf_base.pages[-1]
+            emplaced_page = True
+
+        # Calculate if the text is misaligned compared to the content
+        if emplaced_page:
+            content_rotation = autorotate_correction
+        text_rotation = autorotate_correction
+        text_misaligned = (text_rotation - content_rotation) % 360
+        log.debug(
+            f"Text rotation: (text, autorotate, content) -> text misalignment = "
+            f"({text_rotation}, {autorotate_correction}, {content_rotation}) -> {text_misaligned}"
+        )
+
+        if textpdf and self.font:
+            # Graft the text layer onto this page, whether new or old, possibly
+            # rotating the text layer by the amount is misaligned.
+            strip_old = self.context.options.redo_ocr
+            self._graft_text_layer(
+                page_num=pageno + 1,
+                textpdf=textpdf,
+                font=self.font,
+                font_key=self.font_key,
+                text_rotation=text_misaligned,
+                procset=self.procset,
+                strip_old_text=strip_old,
+            )
+
+        # Correct the overall page rotation if needed, now that the text and content
+        # are aligned
+        page_rotation = (content_rotation - autorotate_correction) % 360
+        self.pdf_base.pages[pageno].Rotate = page_rotation
+        log.debug(
+            f"Page rotation: (content, auto) -> page = "
+            f"({content_rotation}, {autorotate_correction}) -> {page_rotation}"
+        )
+        if self.emplacements % MAX_REPLACE_PAGES == 0:
+            self.save_and_reload()
+
+    def save_and_reload(self):
+        """Save and reload the Pdf.
+
+        This will keep a lid on our memory usage for very large files. Attach
+        the font to page 1 even if page 1 doesn't use it, so we have a way to get it
+        back.
+        """
+
+        page0 = self.pdf_base.pages[0]
+        _update_resources(
+            obj=page0, font=self.font, font_key=self.font_key, procset=self.procset
+        )
+
+        # We cannot read and write the same file, that will corrupt it
+        # but we don't to keep more copies than we need to. Delete intermediates.
+        # {interim_count} is the opened file we were updating
+        # {interim_count - 1} can be deleted
+        # {interim_count + 1} is the new file will produce and open
+        old_file = self.output_file.with_suffix(f'.working{self.interim_count - 1}.pdf')
+        if not self.context.options.keep_temporary_files:
+            with suppress(FileNotFoundError):
+                old_file.unlink()
+
+        next_file = self.output_file.with_suffix(
+            f'.working{self.interim_count + 1}.pdf'
+        )
+        self.pdf_base.save(next_file)
+        self.pdf_base.close()
+
+        self.pdf_base = Pdf.open(next_file)
+        self.procset = self.pdf_base.pages[0].Resources.ProcSet
+        self.font, self.font_key = None, None  # Ensure we reacquire this information
+        self.interim_count += 1
+
+    def finalize(self):
+        self.pdf_base.save(self.output_file)
+        self.pdf_base.close()
+        return self.output_file
+
+    def _find_font(self, text):
+        """Copy a font from the filename text into pdf_base"""
+
+        font, font_key = None, None
+        possible_font_names = ('/f-0-0', '/F1')
+        try:
+            with Pdf.open(text) as pdf_text:
+                try:
+                    pdf_text_fonts = pdf_text.pages[0].Resources.get('/Font', {})
+                except (AttributeError, IndexError, KeyError):
+                    return None, None
+                pdf_text_font = None
+                for f in possible_font_names:
+                    pdf_text_font = pdf_text_fonts.get(f, None)
+                    if pdf_text_font is not None:
+                        font_key = f
+                        break
+                if pdf_text_font:
+                    font = self.pdf_base.copy_foreign(pdf_text_font)
+                return font, font_key
+        except (FileNotFoundError, PdfError):
+            # PdfError occurs if a 0-length file is written e.g. due to OCR timeout
+            return None, None
+
+    def _graft_text_layer(
+        self,
+        *,
+        page_num: int,
+        textpdf: Path,
+        font: Object,
+        font_key: Object,
+        procset: Object,
+        text_rotation: int,
+        strip_old_text: bool,
+    ):
+        """Insert the text layer from text page 0 on to pdf_base at page_num"""
+
+        log.debug("Grafting")
+        if Path(textpdf).stat().st_size == 0:
+            return
+
+        # This is a pointer indicating a specific page in the base file
+        with Pdf.open(textpdf) as pdf_text:
+            pdf_text_contents = pdf_text.pages[0].Contents.read_bytes()
+
+            base_page = self.pdf_base.pages.p(page_num)
+
+            # The text page always will be oriented up by this stage but the original
+            # content may have a rotation applied. Wrap the text stream with a rotation
+            # so it will be oriented the same way as the rest of the page content.
+            # (Previous versions OCRmyPDF rotated the content layer to match the text.)
+            mediabox = [float(pdf_text.pages[0].MediaBox[v]) for v in range(4)]
+            wt, ht = mediabox[2] - mediabox[0], mediabox[3] - mediabox[1]
+
+            mediabox = [float(base_page.MediaBox[v]) for v in range(4)]
+            wp, hp = mediabox[2] - mediabox[0], mediabox[3] - mediabox[1]
+
+            translate = PdfMatrix().translated(-wt / 2, -ht / 2)
+            untranslate = PdfMatrix().translated(wp / 2, hp / 2)
+            corner = PdfMatrix().translated(mediabox[0], mediabox[1])
+            # -rotation because the input is a clockwise angle and this formula
+            # uses CCW
+            text_rotation = -text_rotation % 360
+            rotate = PdfMatrix().rotated(text_rotation)
+
+            # Because of rounding of DPI, we might get a text layer that is not
+            # identically sized to the target page. Scale to adjust. Normally this
+            # is within 0.998.
+            if text_rotation in (90, 270):
+                wt, ht = ht, wt
+            scale_x = wp / wt
+            scale_y = hp / ht
+
+            # log.debug('%r', scale_x, scale_y)
+            scale = PdfMatrix().scaled(scale_x, scale_y)
+
+            # Translate the text so it is centered at (0, 0), rotate it there, adjust
+            # for a size different between initial and text PDF, then untranslate, and
+            # finally move the lower left corner to match the mediabox
+            ctm = translate @ rotate @ scale @ untranslate @ corner
+
+            base_resources = _ensure_dictionary(base_page, Name.Resources)
+            base_xobjs = _ensure_dictionary(base_resources, Name.XObject)
+            text_xobj_name = Name('/' + str(uuid.uuid4()))
+            xobj = self.pdf_base.make_stream(pdf_text_contents)
+            base_xobjs[text_xobj_name] = xobj
+            xobj.Type = Name.XObject
+            xobj.Subtype = Name.Form
+            xobj.FormType = 1
+            xobj.BBox = mediabox
+            _update_resources(
+                obj=xobj, font=font, font_key=font_key, procset=[Name.PDF]
+            )
+
+            pdf_draw_xobj = (
+                (b'q %s cm\n' % ctm.encode()) + (b'%s Do\n' % text_xobj_name) + b'\nQ\n'
+            )
+            new_text_layer = Stream(self.pdf_base, pdf_draw_xobj)
+
+            if strip_old_text:
+                strip_invisible_text(self.pdf_base, base_page)
+
+            base_page.contents_add(new_text_layer, prepend=True)
+
+            _update_resources(
+                obj=base_page, font=font, font_key=font_key, procset=procset
+            )

src/ocrmypdf/_jobcontext.py

@@ -0,0 +1,103 @@
+# © 2018 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import os
+import shutil
+import sys
+from argparse import Namespace
+from copy import copy
+from pathlib import Path
+from typing import Iterator
+
+from pluggy import PluginManager
+
+from ocrmypdf.pdfinfo import PdfInfo
+from ocrmypdf.pdfinfo.info import PageInfo
+
+
+class PdfContext:
+    """Holds the context for a particular run of the pipeline."""
+
+    options: Namespace  #: The specified options for processing this PDF.
+    origin: Path  #: The filename of the original input file.
+    pdfinfo: PdfInfo  #: Detailed data for this PDF.
+    plugin_manager: PluginManager  #: PluginManager for processing the current PDF.
+
+    def __init__(
+        self,
+        options: Namespace,
+        work_folder: Path,
+        origin: Path,
+        pdfinfo: PdfInfo,
+        plugin_manager,
+    ):
+        self.options = options
+        self.work_folder = work_folder
+        self.origin = origin
+        self.pdfinfo = pdfinfo
+        self.plugin_manager = plugin_manager
+
+    def get_path(self, name: str) -> Path:
+        """Generate a ``Path`` for an intermediate file involved in processing.
+
+        The path will be in a temporary folder that is common for all processing
+        of this particular PDF.
+        """
+        return self.work_folder / name
+
+    def get_page_contexts(self) -> Iterator['PageContext']:
+        """Get all ``PageContext`` for this PDF."""
+        npages = len(self.pdfinfo)
+        for n in range(npages):
+            yield PageContext(self, n)
+
+
+class PageContext:
+    """Holds our context for a page.
+
+    Must be pickable, so stores only intrinsic/simple data elements or those
+    capable of their serializing themselves via ``__getstate__``.
+    """
+
+    options: Namespace  #: The specified options for processing this PDF.
+    origin: Path  #: The filename of the original input file.
+    pageno: int  #: This page number (zero-based).
+    pageinfo: PageInfo  #: Information on this page.
+    plugin_manager: PluginManager  #: PluginManager for processing the current PDF.
+
+    def __init__(self, pdf_context: PdfContext, pageno):
+        self.work_folder = pdf_context.work_folder
+        self.origin = pdf_context.origin
+        self.options = pdf_context.options
+        self.pageno = pageno
+        self.pageinfo = pdf_context.pdfinfo[pageno]
+        self.plugin_manager = pdf_context.plugin_manager
+
+    def get_path(self, name: str) -> Path:
+        """Generate a ``Path`` for a file that is part of processing this page.
+
+        The path will be based in a common temporary folder and have a prefix based
+        on the page number.
+        """
+        return self.work_folder / ("%06d_%s" % (self.pageno + 1, name))
+
+    def __getstate__(self):
+        state = self.__dict__.copy()
+
+        state['options'] = copy(self.options)
+        if not isinstance(state['options'].input_file, (str, bytes, os.PathLike)):
+            state['options'].input_file = 'stream'
+        if not isinstance(state['options'].output_file, (str, bytes, os.PathLike)):
+            state['options'].output_file = 'stream'
+        return state
+
+
+def cleanup_working_files(work_folder: Path, options: Namespace):
+    if options.keep_temporary_files:
+        print(f"Temporary working files retained at:\n{work_folder}", file=sys.stderr)
+    else:
+        shutil.rmtree(work_folder, ignore_errors=True)

src/ocrmypdf/_logging.py

@@ -0,0 +1,42 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import logging
+import sys
+from contextlib import suppress
+
+from tqdm import tqdm
+
+
+class PageNumberFilter(logging.Filter):
+    def filter(self, record):
+        pageno = getattr(record, 'pageno', None)
+        if isinstance(pageno, int):
+            record.pageno = f'{pageno:5d} '
+        elif pageno is None:
+            record.pageno = ''
+        return True
+
+
+class TqdmConsole:
+    """Wrapper to log messages in a way that is compatible with tqdm progress bar
+
+    This routes log messages through tqdm so that it can print them above the
+    progress bar, and then refresh the progress bar, rather than overwriting
+    it which looks messy.
+    """
+
+    def __init__(self, file):
+        self.file = file
+
+    def write(self, msg):
+        # When no progress bar is active, tqdm.write() routes to print()
+        tqdm.write(msg.rstrip(), end='\n', file=self.file)
+
+    def flush(self):
+        with suppress(AttributeError):
+            self.file.flush()

src/ocrmypdf/_pipeline.py

@@ -0,0 +1,895 @@
+# © 2016 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import logging
+import os
+import re
+import sys
+from contextlib import suppress
+from datetime import datetime, timezone
+from pathlib import Path
+from shutil import copyfileobj
+from typing import Dict, Iterable, Optional
+
+import img2pdf
+import pikepdf
+from pikepdf.models.metadata import encode_pdf_date
+from PIL import Image, ImageColor, ImageDraw
+
+from ocrmypdf._concurrent import Executor
+from ocrmypdf._exec import unpaper
+from ocrmypdf._jobcontext import PageContext, PdfContext
+from ocrmypdf._version import PROGRAM_NAME
+from ocrmypdf._version import __version__ as VERSION
+from ocrmypdf.exceptions import (
+    DpiError,
+    EncryptedPdfError,
+    InputFileError,
+    PriorOcrFoundError,
+    UnsupportedImageFormatError,
+)
+from ocrmypdf.helpers import Resolution, safe_symlink
+from ocrmypdf.hocrtransform import HocrTransform
+from ocrmypdf.optimize import optimize
+from ocrmypdf.pdfa import generate_pdfa_ps
+from ocrmypdf.pdfinfo import Colorspace, Encoding, PdfInfo
+
+log = logging.getLogger(__name__)
+
+VECTOR_PAGE_DPI = 400
+
+
+def triage_image_file(input_file, output_file, options):
+    log.info("Input file is not a PDF, checking if it is an image...")
+    try:
+        im = Image.open(input_file)
+    except OSError as e:
+        # Recover the original filename
+        log.error(str(e).replace(str(input_file), str(options.input_file)))
+        raise UnsupportedImageFormatError() from e
+
+    with im:
+        log.info("Input file is an image")
+        if 'dpi' in im.info:
+            if im.info['dpi'] <= (96, 96) and not options.image_dpi:
+                log.info("Image size: (%d, %d)", *im.size)
+                log.info("Image resolution: (%d, %d)", *im.info['dpi'])
+                log.error(
+                    "Input file is an image, but the resolution (DPI) is "
+                    "not credible.  Estimate the resolution at which the "
+                    "image was scanned and specify it using --image-dpi."
+                )
+                raise DpiError()
+        elif not options.image_dpi:
+            log.info("Image size: (%d, %d)", *im.size)
+            log.error(
+                "Input file is an image, but has no resolution (DPI) "
+                "in its metadata.  Estimate the resolution at which "
+                "image was scanned and specify it using --image-dpi."
+            )
+            raise DpiError()
+
+        if im.mode in ('RGBA', 'LA'):
+            log.error(
+                "The input image has an alpha channel. Remove the alpha "
+                "channel first."
+            )
+            raise UnsupportedImageFormatError()
+
+        if 'iccprofile' not in im.info:
+            if im.mode == 'RGB':
+                log.info("Input image has no ICC profile, assuming sRGB")
+            elif im.mode == 'CMYK':
+                log.error("Input CMYK image has no ICC profile, not usable")
+                raise UnsupportedImageFormatError()
+
+    try:
+        log.info("Image seems valid. Try converting to PDF...")
+        layout_fun = img2pdf.default_layout_fun
+        if options.image_dpi:
+            layout_fun = img2pdf.get_fixed_dpi_layout_fun(
+                Resolution(options.image_dpi, options.image_dpi)
+            )
+        with open(output_file, 'wb') as outf:
+            img2pdf.convert(
+                os.fspath(input_file),
+                layout_fun=layout_fun,
+                with_pdfrw=False,
+                outputstream=outf,
+            )
+        log.info("Successfully converted to PDF, processing...")
+    except img2pdf.ImageOpenError as e:
+        log.error(e)
+        raise UnsupportedImageFormatError() from e
+
+
+def _pdf_guess_version(input_file, search_window=1024):
+    """Try to find version signature at start of file.
+
+    Not robust enough to deal with appended files.
+
+    Returns empty string if not found, indicating file is probably not PDF.
+    """
+
+    with open(input_file, 'rb') as f:
+        signature = f.read(search_window)
+    m = re.search(br'%PDF-(\d\.\d)', signature)
+    if m:
+        return m.group(1)
+    return ''
+
+
+def triage(original_filename, input_file, output_file, options):
+    try:
+        if _pdf_guess_version(input_file):
+            if options.image_dpi:
+                log.warning(
+                    "Argument --image-dpi is being ignored because the "
+                    "input file is a PDF, not an image."
+                )
+            # Origin file is a pdf create a symlink with pdf extension
+            safe_symlink(input_file, output_file)
+            return output_file
+    except OSError as e:
+        log.debug(f"Temporary file was at: {input_file}")
+        msg = str(e).replace(str(input_file), original_filename)
+        raise InputFileError(msg) from e
+
+    triage_image_file(input_file, output_file, options)
+    return output_file
+
+
+def get_pdfinfo(
+    input_file,
+    *,
+    executor: Executor,
+    detailed_analysis=False,
+    progbar=False,
+    max_workers=None,
+    check_pages=None,
+) -> PdfInfo:
+    try:
+        return PdfInfo(
+            input_file,
+            detailed_analysis=detailed_analysis,
+            progbar=progbar,
+            max_workers=max_workers,
+            check_pages=check_pages,
+            executor=executor,
+        )
+    except pikepdf.PasswordError as e:
+        raise EncryptedPdfError() from e
+    except pikepdf.PdfError as e:
+        raise InputFileError() from e
+
+
+def validate_pdfinfo_options(context: PdfContext):
+    pdfinfo = context.pdfinfo
+    options = context.options
+
+    if pdfinfo.needs_rendering:
+        log.error(
+            "This PDF contains dynamic XFA forms created by Adobe LiveCycle "
+            "Designer and can only be read by Adobe Acrobat or Adobe Reader."
+        )
+        raise InputFileError()
+    if pdfinfo.has_userunit and options.output_type.startswith('pdfa'):
+        log.error(
+            "This input file uses a PDF feature that is not supported "
+            "by Ghostscript, so you cannot use --output-type=pdfa for this "
+            "file. (Specifically, it uses the PDF-1.6 /UserUnit feature to "
+            "support very large or small page sizes, and Ghostscript cannot "
+            "output these files.)  Use --output-type=pdf instead."
+        )
+        raise InputFileError()
+    if pdfinfo.has_acroform:
+        if options.redo_ocr:
+            log.error(
+                "This PDF has a user fillable form. --redo-ocr is not "
+                "currently possible on such files."
+            )
+            raise InputFileError()
+        else:
+            log.warning(
+                "This PDF has a fillable form. "
+                "Chances are it is a pure digital "
+                "document that does not need OCR."
+            )
+            if not options.force_ocr:
+                log.info(
+                    "Use the option --force-ocr to produce an image of the "
+                    "form and all filled form fields. The output PDF will be "
+                    "'flattened' and will no longer be fillable."
+                )
+    context.plugin_manager.hook.validate(pdfinfo=pdfinfo, options=options)
+
+
+def _vector_page_dpi(pageinfo):
+    return VECTOR_PAGE_DPI if pageinfo.has_vector or pageinfo.has_text else 0.0
+
+
+def get_page_dpi(pageinfo, options):
+    "Get the DPI when nonsquare DPI is tolerable"
+    xres = max(
+        pageinfo.dpi.x or VECTOR_PAGE_DPI,
+        options.oversample or 0.0,
+        _vector_page_dpi(pageinfo),
+    )
+    yres = max(
+        pageinfo.dpi.y or VECTOR_PAGE_DPI,
+        options.oversample or 0,
+        _vector_page_dpi(pageinfo),
+    )
+    return Resolution(float(xres), float(yres))
+
+
+def get_page_square_dpi(pageinfo, options) -> Resolution:
+    "Get the DPI when we require xres == yres, scaled to physical units"
+    xres = pageinfo.dpi.x or 0.0
+    yres = pageinfo.dpi.y or 0.0
+    userunit = float(pageinfo.userunit) or 1.0
+    units = float(
+        max(
+            (xres * userunit) or VECTOR_PAGE_DPI,
+            (yres * userunit) or VECTOR_PAGE_DPI,
+            _vector_page_dpi(pageinfo),
+            options.oversample or 0.0,
+        )
+    )
+    return Resolution(units, units)
+
+
+def get_canvas_square_dpi(pageinfo, options) -> Resolution:
+    """Get the DPI when we require xres == yres, in Postscript units"""
+    units = float(
+        max(
+            (pageinfo.dpi.x) or VECTOR_PAGE_DPI,
+            (pageinfo.dpi.y) or VECTOR_PAGE_DPI,
+            _vector_page_dpi(pageinfo),
+            options.oversample or 0.0,
+        )
+    )
+    return Resolution(units, units)
+
+
+def is_ocr_required(page_context: PageContext):
+    pageinfo = page_context.pageinfo
+    options = page_context.options
+
+    ocr_required = True
+
+    if options.pages and pageinfo.pageno not in options.pages:
+        log.debug(f"skipped {pageinfo.pageno} as requested by --pages {options.pages}")
+        ocr_required = False
+    elif pageinfo.has_text:
+        if not options.force_ocr and not (options.skip_text or options.redo_ocr):
+            raise PriorOcrFoundError(
+                "page already has text! - aborting (use --force-ocr to force OCR; "
+                " see also help for the arguments --skip-text and --redo-ocr"
+            )
+        elif options.force_ocr:
+            log.info("page already has text! - rasterizing text and running OCR anyway")
+            ocr_required = True
+        elif options.redo_ocr:
+            if pageinfo.has_corrupt_text:
+                log.warning(
+                    "some text on this page cannot be mapped to characters: "
+                    "consider using --force-ocr instead"
+                )
+            else:
+                log.info("redoing OCR")
+            ocr_required = True
+        elif options.skip_text:
+            log.info("skipping all processing on this page")
+            ocr_required = False
+    elif not pageinfo.images and not options.lossless_reconstruction:
+        # We found a page with no images and no text. That means it may
+        # have vector art that the user wants to OCR. If we determined
+        # lossless reconstruction is not possible then we have to rasterize
+        # the image. So if OCR is being forced, take that to mean YES, go
+        # ahead and rasterize. If not forced, then pretend there's no text
+        # on the page at all so we don't lose anything.
+        # This could be made smarter by explicitly searching for vector art.
+        if options.force_ocr and options.oversample:
+            # The user really wants to reprocess this file
+            log.info(
+                "page has no images - "
+                f"rasterizing at {options.oversample} DPI because "
+                "--force-ocr --oversample was specified"
+            )
+        elif options.force_ocr:
+            # Warn the user they might not want to do this
+            log.warning(
+                "page has no images - "
+                "all vector content will be "
+                f"rasterized at {VECTOR_PAGE_DPI} DPI, losing some resolution and likely "
+                "increasing file size. Use --oversample to adjust the "
+                "DPI."
+            )
+        else:
+            log.info(
+                "page has no images - "
+                "skipping all processing on this page to avoid losing detail. "
+                "Use --force-ocr if you wish to perform OCR on pages that "
+                "have vector content."
+            )
+            ocr_required = False
+
+    if ocr_required and options.skip_big and pageinfo.images:
+        pixel_count = pageinfo.width_pixels * pageinfo.height_pixels
+        if pixel_count > (options.skip_big * 1_000_000):
+            ocr_required = False
+            log.warning(
+                "page too big, skipping OCR "
+                f"({(pixel_count / 1_000_000):.1f} MPixels > {options.skip_big:.1f} MPixels --skip-big)"
+            )
+    return ocr_required
+
+
+def rasterize_preview(input_file: Path, page_context: PageContext):
+    output_file = page_context.get_path('rasterize_preview.jpg')
+    canvas_dpi = get_canvas_square_dpi(page_context.pageinfo, page_context.options)
+    page_dpi = get_page_square_dpi(page_context.pageinfo, page_context.options)
+    page_context.plugin_manager.hook.rasterize_pdf_page(
+        input_file=input_file,
+        output_file=output_file,
+        raster_device='jpeggray',
+        raster_dpi=canvas_dpi,
+        pageno=page_context.pageinfo.pageno + 1,
+        page_dpi=page_dpi,
+        rotation=0,
+        filter_vector=False,
+    )
+    return output_file
+
+
+def describe_rotation(page_context: PageContext, orient_conf, correction: int):
+    """
+    Describe the page rotation we are going to perform.
+    """
+    direction = {0: '⇧', 90: '⇨', 180: '⇩', 270: '⇦'}
+    turns = {0: ' ', 90: '⬏', 180: '↻', 270: '⬑'}
+
+    existing_rotation = page_context.pageinfo.rotation
+    action = ''
+    if orient_conf.confidence >= page_context.options.rotate_pages_threshold:
+        if correction != 0:
+            action = 'will rotate ' + turns[correction]
+        else:
+            action = 'rotation appears correct'
+    else:
+        if correction != 0:
+            action = 'confidence too low to rotate'
+        else:
+            action = 'no change'
+
+    facing = ''
+
+    if existing_rotation != 0:
+        facing = f"with existing rotation {direction.get(existing_rotation, '?')}, "
+    facing += f"page is facing {direction.get(orient_conf.angle, '?')}"
+
+    return f"{facing}, confidence {orient_conf.confidence:.2f} - {action}"
+
+
+def get_orientation_correction(preview: Path, page_context: PageContext):
+    """Work out orientation correct for each page.
+
+    We ask Ghostscript to draw a preview page, which will rasterize with the
+    current /Rotate applied, and then ask OCR which way the page is
+    oriented. If the value of /Rotate is correct (e.g., a user already
+    manually fixed rotation), then OCR will say the page is pointing
+    up and the correction is zero. Otherwise, the orientation found by
+    OCR represents the clockwise rotation, or the counterclockwise
+    correction to rotation.
+
+    When we draw the real page for OCR, we rotate it by the CCW correction,
+    which points it (hopefully) upright. _graft.py takes care of the orienting
+    the image and text layers.
+    """
+
+    orient_conf = page_context.plugin_manager.hook.get_ocr_engine().get_orientation(
+        preview, page_context.options
+    )
+
+    correction = orient_conf.angle % 360
+    log.info(describe_rotation(page_context, orient_conf, correction))
+    if (
+        orient_conf.confidence >= page_context.options.rotate_pages_threshold
+        and correction != 0
+    ):
+        return correction
+
+    return 0
+
+
+def rasterize(
+    input_file: Path,
+    page_context: PageContext,
+    correction: int = 0,
+    output_tag: str = '',
+    remove_vectors=None,
+):
+    colorspaces = ['pngmono', 'pnggray', 'png256', 'png16m']
+    device_idx = 0
+
+    if remove_vectors is None:
+        remove_vectors = page_context.options.remove_vectors
+
+    output_file = page_context.get_path(f'rasterize{output_tag}.png')
+    pageinfo = page_context.pageinfo
+
+    def at_least(cs):
+        return max(device_idx, colorspaces.index(cs))
+
+    for image in pageinfo.images:
+        if image.type_ != 'image':
+            continue  # ignore masks
+        if image.bpc > 1:
+            if image.color == Colorspace.index:
+                device_idx = at_least('png256')
+            elif image.color == Colorspace.gray:
+                device_idx = at_least('pnggray')
+            else:
+                device_idx = at_least('png16m')
+
+    if pageinfo.has_vector:
+        device_idx = at_least('png16m')
+
+    device = colorspaces[device_idx]
+
+    log.debug(f"Rasterize with {device}, rotation {correction}")
+
+    # Produce the page image with square resolution or else deskew and OCR
+    # will not work properly.
+    canvas_dpi = get_canvas_square_dpi(pageinfo, page_context.options)
+    page_dpi = get_page_square_dpi(pageinfo, page_context.options)
+
+    page_context.plugin_manager.hook.rasterize_pdf_page(
+        input_file=input_file,
+        output_file=output_file,
+        raster_device=device,
+        raster_dpi=canvas_dpi,
+        page_dpi=page_dpi,
+        pageno=pageinfo.pageno + 1,
+        rotation=correction,
+        filter_vector=remove_vectors,
+    )
+    return output_file
+
+
+def preprocess_remove_background(input_file: Path, page_context: PageContext):
+    if any(image.bpc > 1 for image in page_context.pageinfo.images):
+        output_file = page_context.get_path('pp_rm_bg.png')
+        # leptonica.remove_background(input_file, output_file)
+        raise NotImplementedError("--remove-background is temporarily not implemented")
+        return output_file
+    else:
+        log.info("background removal skipped on mono page")
+        return input_file
+
+
+def preprocess_deskew(input_file: Path, page_context: PageContext):
+    output_file = page_context.get_path('pp_deskew.png')
+    dpi = get_page_square_dpi(page_context.pageinfo, page_context.options)
+
+    ocr_engine = page_context.plugin_manager.hook.get_ocr_engine()
+    deskew_angle_degrees = ocr_engine.get_deskew(input_file, page_context.options)
+
+    with Image.open(input_file) as im:
+        # According to Pillow docs, .rotate() will automatically use Image.NEAREST
+        # resampling if image is mode '1' or 'P'
+        deskewed = im.rotate(
+            deskew_angle_degrees, resample=Image.BICUBIC, fillcolor='white'
+        )
+        deskewed.save(output_file, dpi=dpi)
+
+    return output_file
+
+
+def preprocess_clean(input_file: Path, page_context: PageContext):
+    output_file = page_context.get_path('pp_clean.png')
+    dpi = get_page_square_dpi(page_context.pageinfo, page_context.options)
+    unpaper.clean(
+        input_file,
+        output_file,
+        dpi=dpi.x,
+        unpaper_args=page_context.options.unpaper_args,
+    )
+    return output_file
+
+
+def create_ocr_image(image: Path, page_context: PageContext):
+    """Create the image we send for OCR. May not be the same as the display
+    image depending on preprocessing. This image will never be shown to the
+    user."""
+
+    output_file = page_context.get_path('ocr.png')
+    options = page_context.options
+    with Image.open(image) as im:
+        white = ImageColor.getcolor('#ffffff', im.mode)
+        # pink = ImageColor.getcolor('#ff0080', im.mode)
+        draw = ImageDraw.ImageDraw(im)
+
+        log.debug('resolution %r', im.info['dpi'])
+
+        if not options.force_ocr:
+            # Do not mask text areas when forcing OCR, because we need to OCR
+            # all text areas
+            mask = None  # Exclude both visible and invisible text from OCR
+            if options.redo_ocr:
+                mask = True  # Mask visible text, but not invisible text
+
+            for textarea in page_context.pageinfo.get_textareas(
+                visible=mask, corrupt=None
+            ):
+                # Calculate resolution based on the image size and page dimensions
+                # without regard whatever resolution is in pageinfo (may differ or
+                # be None)
+                bbox = [float(v) for v in textarea]
+                xyscale = tuple(float(coord) / 72.0 for coord in im.info['dpi'])
+                pixcoords = (
+                    bbox[0] * xyscale[0],
+                    im.height - bbox[3] * xyscale[1],
+                    bbox[2] * xyscale[0],
+                    im.height - bbox[1] * xyscale[1],
+                )
+                log.debug('blanking %r', pixcoords)
+                draw.rectangle(pixcoords, fill=white)
+                # draw.rectangle(pixcoords, outline=pink)
+        del draw
+
+        filter_im = page_context.plugin_manager.hook.filter_ocr_image(
+            page=page_context, image=im
+        )
+        if filter_im is not None:
+            im = filter_im
+
+        # Pillow requires integer DPI
+        dpi = tuple(round(coord) for coord in im.info['dpi'])
+        im.save(output_file, dpi=dpi)
+    return output_file
+
+
+def ocr_engine_hocr(input_file: Path, page_context: PageContext):
+    hocr_out = page_context.get_path('ocr_hocr.hocr')
+    hocr_text_out = page_context.get_path('ocr_hocr.txt')
+    options = page_context.options
+
+    ocr_engine = page_context.plugin_manager.hook.get_ocr_engine()
+    ocr_engine.generate_hocr(
+        input_file=input_file,
+        output_hocr=hocr_out,
+        output_text=hocr_text_out,
+        options=options,
+    )
+    return (hocr_out, hocr_text_out)
+
+
+def should_visible_page_image_use_jpg(pageinfo):
+    # If all images were JPEGs originally, produce a JPEG as output
+    return pageinfo.images and all(im.enc == Encoding.jpeg for im in pageinfo.images)
+
+
+def create_visible_page_jpg(image: Path, page_context: PageContext) -> Path:
+    output_file = page_context.get_path('visible.jpg')
+    with Image.open(image) as im:
+        # At this point the image should be a .png, but deskew, unpaper
+        # might have removed the DPI information. In this case, fall back to
+        # square DPI used to rasterize. When the preview image was
+        # rasterized, it was also converted to square resolution, which is
+        # what we want to give to the OCR engine, so keep it square.
+        if 'dpi' in im.info:
+            dpi = Resolution(*im.info['dpi'])
+        else:
+            # Fallback to page-implied DPI
+            dpi = get_page_square_dpi(page_context.pageinfo, page_context.options)
+
+        # Pillow requires integer DPI
+        im.save(output_file, format='JPEG', dpi=dpi.to_int())
+    return output_file
+
+
+def create_pdf_page_from_image(
+    image: Path, page_context: PageContext, orientation_correction
+):
+    # We rasterize a square DPI version of each page because most image
+    # processing tools don't support rectangular DPI. Use the square DPI as it
+    # accurately describes the image. It would be possible to resample the image
+    # at this stage back to non-square DPI to more closely resemble the input,
+    # except that the hocr renderer does not understand non-square DPI. The
+    # sandwich renderer would be fine.
+    output_file = page_context.get_path('visible.pdf')
+
+    pageinfo = page_context.pageinfo
+    pagesize = 72.0 * float(pageinfo.width_inches), 72.0 * float(pageinfo.height_inches)
+    effective_rotation = (pageinfo.rotation - orientation_correction) % 360
+    if effective_rotation % 180 == 90:
+        pagesize = pagesize[1], pagesize[0]
+
+    # This create a single page PDF
+    with open(image, 'rb') as imfile, open(output_file, 'wb') as pdf:
+        log.debug('convert')
+
+        layout_fun = img2pdf.get_layout_fun(pagesize)
+        img2pdf.convert(
+            imfile, with_pdfrw=False, layout_fun=layout_fun, outputstream=pdf
+        )
+        log.debug('convert done')
+
+    output_file = page_context.plugin_manager.hook.filter_pdf_page(
+        page=page_context, image_filename=image, output_pdf=output_file
+    )
+
+    return output_file
+
+
+def render_hocr_page(hocr: Path, page_context: PageContext):
+    options = page_context.options
+    output_file = page_context.get_path('ocr_hocr.pdf')
+    dpi = get_page_square_dpi(page_context.pageinfo, options)
+    debug_mode = options.pdf_renderer == 'hocrdebug'
+
+    hocrtransform = HocrTransform(hocr_filename=hocr, dpi=dpi.x)  # square
+    hocrtransform.to_pdf(
+        out_filename=output_file,
+        image_filename=None,
+        show_bounding_boxes=False if not debug_mode else True,
+        invisible_text=True if not debug_mode else False,
+        interword_spaces=True,
+    )
+    return output_file
+
+
+def ocr_engine_textonly_pdf(input_image: Path, page_context: PageContext):
+    output_pdf = page_context.get_path('ocr_tess.pdf')
+    output_text = page_context.get_path('ocr_tess.txt')
+    options = page_context.options
+
+    ocr_engine = page_context.plugin_manager.hook.get_ocr_engine()
+    ocr_engine.generate_pdf(
+        input_file=input_image,
+        output_pdf=output_pdf,
+        output_text=output_text,
+        options=options,
+    )
+    return (output_pdf, output_text)
+
+
+def get_docinfo(base_pdf: pikepdf.Pdf, context: PdfContext) -> Dict[str, str]:
+    options = context.options
+
+    def from_document_info(key):
+        try:
+            s = base_pdf.docinfo[key]
+            return str(s)
+        except (KeyError, TypeError):
+            return ''
+
+    pdfmark = {
+        k: from_document_info(k)
+        for k in ('/Title', '/Author', '/Keywords', '/Subject', '/CreationDate')
+    }
+    if options is not None:
+        if options.title:
+            pdfmark['/Title'] = options.title
+        if options.author:
+            pdfmark['/Author'] = options.author
+        if options.keywords:
+            pdfmark['/Keywords'] = options.keywords
+        if options.subject:
+            pdfmark['/Subject'] = options.subject
+
+    creator_tag = context.plugin_manager.hook.get_ocr_engine().creator_tag(options)
+
+    pdfmark['/Creator'] = f'{PROGRAM_NAME} {VERSION} / {creator_tag}'
+    pdfmark['/Producer'] = f'pikepdf {pikepdf.__version__}'
+    pdfmark['/ModDate'] = encode_pdf_date(datetime.now(timezone.utc))
+    return pdfmark
+
+
+def generate_postscript_stub(context: PdfContext):
+    output_file = context.get_path('pdfa.ps')
+    generate_pdfa_ps(output_file)
+    return output_file
+
+
+def convert_to_pdfa(input_pdf: Path, input_ps_stub: Path, context: PdfContext):
+    options = context.options
+    input_pdfinfo = context.pdfinfo
+    fix_docinfo_file = context.get_path('fix_docinfo.pdf')
+    output_file = context.get_path('pdfa.pdf')
+
+    # If the DocumentInfo record contains NUL characters, Ghostscript will
+    # produce XMP metadata which contains invalid XML entities (&#0;).
+    # NULs in DocumentInfo seem to be common since older Acrobats included them.
+    # pikepdf can deal with this, but we make the world a better place by
+    # stamping them out as soon as possible.
+    modified = False
+    with pikepdf.open(input_pdf) as pdf_file:
+        try:
+            len(pdf_file.docinfo)
+        except TypeError:
+            log.error(
+                "File contains a malformed DocumentInfo block - continuing anyway"
+            )
+        else:
+            if pdf_file.docinfo:
+                for k, v in pdf_file.docinfo.items():
+                    if b'\x00' in bytes(v):
+                        pdf_file.docinfo[k] = bytes(v).replace(b'\x00', b'')
+                        modified = True
+        if modified:
+            pdf_file.save(fix_docinfo_file)
+        else:
+            safe_symlink(input_pdf, fix_docinfo_file)
+
+    context.plugin_manager.hook.generate_pdfa(
+        pdf_version=input_pdfinfo.min_version,
+        pdf_pages=[fix_docinfo_file],
+        pdfmark=input_ps_stub,
+        output_file=output_file,
+        compression=options.pdfa_image_compression,
+        pdfa_part=options.output_type[-1],  # is pdfa-1, pdfa-2, or pdfa-3
+        progressbar_class=(
+            context.plugin_manager.hook.get_progressbar_class()
+            if options.progress_bar
+            else None
+        ),
+    )
+
+    return output_file
+
+
+def should_linearize(working_file: Path, context: PdfContext):
+    filesize = os.stat(working_file).st_size
+    if filesize > (context.options.fast_web_view * 1_000_000):
+        return True
+    return False
+
+
+def get_pdf_save_settings(output_type: str):
+    if output_type == 'pdfa-1':
+        # Trigger recompression to ensure object streams are removed, because
+        # Acrobat complains about them in PDF/A-1b validation.
+        return dict(
+            preserve_pdfa=True,
+            compress_streams=True,
+            stream_decode_level=pikepdf.StreamDecodeLevel.generalized,
+            object_stream_mode=pikepdf.ObjectStreamMode.disable,
+        )
+    else:
+        return dict(
+            preserve_pdfa=True,
+            compress_streams=True,
+            object_stream_mode=(pikepdf.ObjectStreamMode.generate),
+        )
+
+
+def metadata_fixup(working_file: Path, context: PdfContext):
+    output_file = context.get_path('metafix.pdf')
+    options = context.options
+
+    def report_on_metadata(missing):
+        if not missing:
+            return
+        if options.output_type.startswith('pdfa'):
+            log.warning(
+                "Some input metadata could not be copied because it is not "
+                "permitted in PDF/A. You may wish to examine the output "
+                "PDF's XMP metadata."
+            )
+            log.debug("The following metadata fields were not copied: %r", missing)
+        else:
+            log.error(
+                "Some input metadata could not be copied."
+                "You may wish to examine the output PDF's XMP metadata."
+            )
+            log.info("The following metadata fields were not copied: %r", missing)
+
+    with pikepdf.open(context.origin) as original, pikepdf.open(working_file) as pdf:
+        docinfo = get_docinfo(original, context)
+        with pdf.open_metadata() as meta:
+            meta.load_from_docinfo(docinfo, delete_missing=False, raise_failure=False)
+            # If xmp:CreateDate is missing, set it to the modify date to
+            # match Ghostscript, for consistency
+            if 'xmp:CreateDate' not in meta:
+                meta['xmp:CreateDate'] = meta.get('xmp:ModifyDate', '')
+
+            with original.open_metadata(
+                set_pikepdf_as_editor=False, update_docinfo=False, strict=False
+            ) as meta_original:
+                if meta.get('dc:title') == 'Untitled':
+                    # Ghostscript likes to set title to Untitled if omitted from input.
+                    # Reverse this, because PDF/A TechNote 0003:Metadata in PDF/A-1
+                    # and the XMP Spec do not make this recommendation.
+                    if 'dc:title' not in meta_original:
+                        del meta['dc:title']
+                missing = set(meta_original.keys()) - set(meta.keys())
+                report_on_metadata(missing)
+
+        pdf.save(
+            output_file,
+            **get_pdf_save_settings(options.output_type),
+            linearize=(  # Don't linearize if optimize() will be linearizing too
+                should_linearize(working_file, context)
+                if options.optimize == 0
+                else False
+            ),
+        )
+
+    return output_file
+
+
+def optimize_pdf(input_file: Path, context: PdfContext, executor: Executor):
+    output_file = context.get_path('optimize.pdf')
+    save_settings = dict(
+        linearize=should_linearize(input_file, context),
+        **get_pdf_save_settings(context.options.output_type),
+    )
+    optimize(input_file, output_file, context, save_settings, executor)
+    return output_file
+
+
+def enumerate_compress_ranges(iterable):
+    skipped_from, index = None, None
+    for index, txt_file in enumerate(iterable):
+        index += 1
+        if txt_file:
+            if skipped_from is not None:
+                yield (skipped_from, index - 1), None
+                skipped_from = None
+            yield (index, index), txt_file
+        else:
+            if skipped_from is None:
+                skipped_from = index
+    if skipped_from is not None:
+        yield (skipped_from, index), None
+
+
+def merge_sidecars(txt_files: Iterable[Optional[Path]], context: PdfContext):
+    output_file = context.get_path('sidecar.txt')
+    with open(output_file, 'w', encoding="utf-8") as stream:
+        for (frm, to), txt_file in enumerate_compress_ranges(txt_files):
+            if frm != 1:
+                stream.write('\f')  # Form feed between pages
+            if txt_file:
+                with open(txt_file, encoding="utf-8") as in_:
+                    txt = in_.read()
+                    # Some OCR engines (e.g. Tesseract v4 alpha) add form feeds
+                    # between pages, and some do not. For consistency, we ignore
+                    # any added by the OCR engine and them on our own.
+                    if txt.endswith('\f'):
+                        stream.write(txt[:-1])
+                    else:
+                        stream.write(txt)
+            else:
+                if frm != to:
+                    pages = f'{frm}-{to}'
+                else:
+                    pages = f'{frm}'
+                stream.write(f'[OCR skipped on page(s) {pages}]')
+    return output_file
+
+
+def copy_final(input_file, output_file, _context: PdfContext):
+    log.debug('%s -> %s', input_file, output_file)
+    with open(input_file, 'rb') as input_stream:
+        if output_file == '-':
+            copyfileobj(input_stream, sys.stdout.buffer)
+            sys.stdout.flush()
+        elif hasattr(output_file, 'writable'):
+            output_stream = output_file
+            copyfileobj(input_stream, output_stream)
+            with suppress(AttributeError):
+                output_stream.flush()
+        else:
+            # At this point we overwrite the output_file specified by the user
+            # use copyfileobj because then we use open() to create the file and
+            # get the appropriate umask, ownership, etc.
+            with open(output_file, 'wb') as output_stream:
+                copyfileobj(input_stream, output_stream)

src/ocrmypdf/_plugin_manager.py

@@ -0,0 +1,122 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import argparse
+import importlib
+import importlib.util
+import pkgutil
+import sys
+from pathlib import Path
+from typing import List, Tuple, Union
+
+import pluggy
+
+import ocrmypdf.builtin_plugins
+from ocrmypdf import pluginspec
+from ocrmypdf.cli import get_parser, plugins_only_parser
+
+
+class OcrmypdfPluginManager(pluggy.PluginManager):
+    """pluggy.PluginManager that can fork.
+
+    Capable of reconstructing itself in child workers.
+
+    Arguments:
+        setup_func: callback that initializes the plugin manager with all
+            standard plugins
+    """
+
+    def __init__(
+        self,
+        *args,
+        plugins: List[Union[str, Path]],
+        builtins: bool = True,
+        **kwargs,
+    ):
+        self.__init_args = args
+        self.__init_kwargs = kwargs
+        self.__plugins = plugins
+        self.__builtins = builtins
+        super().__init__(*args, **kwargs)
+        self.setup_plugins()
+
+    def __getstate__(self):
+        state = dict(
+            init_args=self.__init_args,
+            plugins=self.__plugins,
+            builtins=self.__builtins,
+            init_kwargs=self.__init_kwargs,
+        )
+        return state
+
+    def __setstate__(self, state):
+        self.__init__(
+            *state['init_args'],
+            plugins=state['plugins'],
+            builtins=state['builtins'],
+            **state['init_kwargs'],
+        )
+
+    def setup_plugins(self):
+        self.add_hookspecs(pluginspec)
+
+        # 1. Register builtins
+        if self.__builtins:
+            for module in sorted(
+                pkgutil.iter_modules(ocrmypdf.builtin_plugins.__path__)
+            ):
+                name = f'ocrmypdf.builtin_plugins.{module.name}'
+                module = importlib.import_module(name)
+                self.register(module)
+
+        # 2. Install semfree if needed
+        try:
+            # pylint: disable=import-outside-toplevel
+            from multiprocessing.synchronize import SemLock
+
+            del SemLock
+        except ImportError:
+            self.register(importlib.import_module('ocrmypdf.extra_plugins.semfree'))
+
+        # 3. Register setuptools plugins
+        self.load_setuptools_entrypoints('ocrmypdf')
+
+        # 4. Register plugins specified on command line
+        for name in self.__plugins:
+            if isinstance(name, Path) or name.endswith('.py'):
+                # Import by filename
+                module_name = Path(name).stem
+                spec = importlib.util.spec_from_file_location(module_name, name)
+                module = importlib.util.module_from_spec(spec)
+                sys.modules[module_name] = module
+                spec.loader.exec_module(module)
+            else:
+                # Import by dotted module name
+                module = importlib.import_module(name)
+            self.register(module)
+
+
+def get_plugin_manager(plugins: List[Union[str, Path]], builtins=True):
+    pm = OcrmypdfPluginManager(
+        project_name='ocrmypdf',
+        plugins=plugins,
+        builtins=builtins,
+    )
+    return pm
+
+
+def get_parser_options_plugins(
+    args,
+) -> Tuple[argparse.ArgumentParser, argparse.Namespace, pluggy.PluginManager]:
+    pre_options, _unused = plugins_only_parser.parse_known_args(args=args)
+    plugin_manager = get_plugin_manager(pre_options.plugins)
+
+    parser = get_parser()
+    plugin_manager.hook.add_options(parser=parser)  # pylint: disable=no-member
+
+    options = parser.parse_args(args=args)
+    return parser, options, plugin_manager

src/ocrmypdf/_sync.py

@@ -0,0 +1,436 @@
+# © 2016 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import logging
+import logging.handlers
+import os
+import sys
+import threading
+from functools import partial
+from pathlib import Path
+from tempfile import mkdtemp
+from typing import List, NamedTuple, Optional, Tuple
+
+import PIL
+
+from ocrmypdf._concurrent import Executor, setup_executor
+from ocrmypdf._graft import OcrGrafter
+from ocrmypdf._jobcontext import PageContext, PdfContext, cleanup_working_files
+from ocrmypdf._logging import PageNumberFilter
+from ocrmypdf._pipeline import (
+    convert_to_pdfa,
+    copy_final,
+    create_ocr_image,
+    create_pdf_page_from_image,
+    create_visible_page_jpg,
+    generate_postscript_stub,
+    get_orientation_correction,
+    get_pdfinfo,
+    is_ocr_required,
+    merge_sidecars,
+    metadata_fixup,
+    ocr_engine_hocr,
+    ocr_engine_textonly_pdf,
+    optimize_pdf,
+    preprocess_clean,
+    preprocess_deskew,
+    preprocess_remove_background,
+    rasterize,
+    rasterize_preview,
+    render_hocr_page,
+    should_visible_page_image_use_jpg,
+    triage,
+    validate_pdfinfo_options,
+)
+from ocrmypdf._plugin_manager import get_plugin_manager
+from ocrmypdf._validation import (
+    check_requested_output_file,
+    create_input_file,
+    report_output_file_size,
+)
+from ocrmypdf.exceptions import ExitCode, ExitCodeException
+from ocrmypdf.helpers import (
+    NeverRaise,
+    available_cpu_count,
+    check_pdf,
+    pikepdf_enable_mmap,
+    samefile,
+)
+from ocrmypdf.pdfa import file_claims_pdfa
+
+log = logging.getLogger(__name__)
+
+
+class PageResult(NamedTuple):  # pylint: disable=inherit-non-class
+    pageno: int
+    pdf_page_from_image: Optional[Path]
+    ocr: Optional[Path]
+    text: Optional[Path]
+    orientation_correction: int
+
+
+tls = threading.local()
+tls.pageno = None
+
+
+old_factory = logging.getLogRecordFactory()
+
+
+def record_factory(*args, **kwargs):
+    record = old_factory(*args, **kwargs)
+    if hasattr(tls, 'pageno'):
+        record.pageno = tls.pageno
+    return record
+
+
+logging.setLogRecordFactory(record_factory)
+
+
+def preprocess(
+    page_context: PageContext,
+    image: Path,
+    remove_background: bool,
+    deskew: bool,
+    clean: bool,
+) -> Path:
+    if remove_background:
+        image = preprocess_remove_background(image, page_context)
+    if deskew:
+        image = preprocess_deskew(image, page_context)
+    if clean:
+        image = preprocess_clean(image, page_context)
+    return image
+
+
+def make_intermediate_images(
+    page_context: PageContext, orientation_correction: int
+) -> Tuple[Path, Optional[Path]]:
+    options = page_context.options
+
+    ocr_image = preprocess_out = None
+    rasterize_out = rasterize(
+        page_context.origin,
+        page_context,
+        correction=orientation_correction,
+        remove_vectors=False,
+    )
+
+    if not any([options.clean, options.clean_final, options.remove_vectors]):
+        ocr_image = preprocess_out = preprocess(
+            page_context,
+            rasterize_out,
+            options.remove_background,
+            options.deskew,
+            clean=False,
+        )
+    else:
+        if not options.lossless_reconstruction:
+            preprocess_out = preprocess(
+                page_context,
+                rasterize_out,
+                options.remove_background,
+                options.deskew,
+                clean=options.clean_final,
+            )
+        if options.remove_vectors:
+            rasterize_ocr_out = rasterize(
+                page_context.origin,
+                page_context,
+                correction=orientation_correction,
+                remove_vectors=True,
+                output_tag='_ocr',
+            )
+        else:
+            rasterize_ocr_out = rasterize_out
+
+        if (
+            preprocess_out
+            and rasterize_ocr_out == rasterize_out
+            and options.clean == options.clean_final
+        ):
+            # Optimization: image for OCR is identical to presentation image
+            ocr_image = preprocess_out
+        else:
+            ocr_image = preprocess(
+                page_context,
+                rasterize_ocr_out,
+                options.remove_background,
+                options.deskew,
+                clean=options.clean,
+            )
+    return ocr_image, preprocess_out
+
+
+def exec_page_sync(page_context: PageContext):
+    options = page_context.options
+    tls.pageno = page_context.pageno + 1
+
+    if not is_ocr_required(page_context):
+        return PageResult(
+            pageno=page_context.pageno,
+            pdf_page_from_image=None,
+            ocr=None,
+            text=None,
+            orientation_correction=0,
+        )
+
+    orientation_correction = 0
+    if options.rotate_pages:
+        # Rasterize
+        rasterize_preview_out = rasterize_preview(page_context.origin, page_context)
+        orientation_correction = get_orientation_correction(
+            rasterize_preview_out, page_context
+        )
+
+    ocr_image, preprocess_out = make_intermediate_images(
+        page_context, orientation_correction
+    )
+    ocr_image_out = create_ocr_image(ocr_image, page_context)
+
+    pdf_page_from_image_out = None
+    if not options.lossless_reconstruction:
+        assert preprocess_out
+        visible_image_out = preprocess_out
+        if should_visible_page_image_use_jpg(page_context.pageinfo):
+            visible_image_out = create_visible_page_jpg(visible_image_out, page_context)
+        filtered_image = page_context.plugin_manager.hook.filter_page_image(
+            page=page_context, image_filename=visible_image_out
+        )
+        if filtered_image:
+            visible_image_out = filtered_image
+        pdf_page_from_image_out = create_pdf_page_from_image(
+            visible_image_out, page_context, orientation_correction
+        )
+
+    if options.pdf_renderer.startswith('hocr'):
+        (hocr_out, text_out) = ocr_engine_hocr(ocr_image_out, page_context)
+        ocr_out = render_hocr_page(hocr_out, page_context)
+    elif options.pdf_renderer == 'sandwich':
+        (ocr_out, text_out) = ocr_engine_textonly_pdf(ocr_image_out, page_context)
+    else:
+        raise NotImplementedError(f"pdf_renderer {options.pdf_renderer}")
+
+    return PageResult(
+        pageno=page_context.pageno,
+        pdf_page_from_image=pdf_page_from_image_out,
+        ocr=ocr_out,
+        text=text_out,
+        orientation_correction=orientation_correction,
+    )
+
+
+def post_process(pdf_file, context: PdfContext, executor: Executor):
+    pdf_out = pdf_file
+    if context.options.output_type.startswith('pdfa'):
+        ps_stub_out = generate_postscript_stub(context)
+        pdf_out = convert_to_pdfa(pdf_out, ps_stub_out, context)
+
+    pdf_out = metadata_fixup(pdf_out, context)
+    return optimize_pdf(pdf_out, context, executor)
+
+
+def worker_init(max_pixels: int):
+    # In Windows, child process will not inherit our change to this value in
+    # the parent process, so ensure workers get it set. Not needed when running
+    # threaded, but harmless to set again.
+    PIL.Image.MAX_IMAGE_PIXELS = max_pixels
+    pikepdf_enable_mmap()
+
+
+def exec_concurrent(context: PdfContext, executor: Executor):
+    """Execute the pipeline concurrently"""
+
+    # Run exec_page_sync on every page context
+    options = context.options
+    max_workers = min(len(context.pdfinfo), options.jobs)
+    if max_workers > 1:
+        log.info("Start processing %d pages concurrently", max_workers)
+
+    sidecars: List[Optional[Path]] = [None] * len(context.pdfinfo)
+    ocrgraft = OcrGrafter(context)
+
+    def update_page(result: PageResult, pbar):
+        try:
+            tls.pageno = result.pageno + 1
+            sidecars[result.pageno] = result.text
+            pbar.update()
+            ocrgraft.graft_page(
+                pageno=result.pageno,
+                image=result.pdf_page_from_image,
+                textpdf=result.ocr,
+                autorotate_correction=result.orientation_correction,
+            )
+            pbar.update()
+        finally:
+            tls.pageno = None
+
+    executor(
+        use_threads=options.use_threads,
+        max_workers=max_workers,
+        tqdm_kwargs=dict(
+            total=(2 * len(context.pdfinfo)),
+            desc='OCR' if options.tesseract_timeout > 0 else 'Image processing',
+            unit='page',
+            unit_scale=0.5,
+            disable=not options.progress_bar,
+        ),
+        worker_initializer=partial(worker_init, PIL.Image.MAX_IMAGE_PIXELS),
+        task=exec_page_sync,
+        task_arguments=context.get_page_contexts(),
+        task_finished=update_page,
+    )
+
+    # Output sidecar text
+    if options.sidecar:
+        text = merge_sidecars(sidecars, context)
+        # Copy text file to destination
+        copy_final(text, options.sidecar, context)
+
+    # Merge layers to one single pdf
+    pdf = ocrgraft.finalize()
+
+    if options.output_type != 'none':
+        # PDF/A and metadata
+        log.info("Postprocessing...")
+        pdf = post_process(pdf, context, executor)
+
+        # Copy PDF file to destination
+        copy_final(pdf, options.output_file, context)
+
+
+def configure_debug_logging(log_filename: Path, prefix: str = ''):
+    """
+    Create a debug log file at a specified location.
+
+    Arguments:
+        log_filename: Where to the put the log file.
+        prefix: The logging domain prefix that should be sent to the log.
+    """
+    log_file_handler = logging.FileHandler(log_filename, delay=True)
+    log_file_handler.setLevel(logging.DEBUG)
+    formatter = logging.Formatter(
+        '[%(asctime)s] - %(name)s - %(levelname)7s -%(pageno)s %(message)s'
+    )
+    log_file_handler.setFormatter(formatter)
+    log_file_handler.addFilter(PageNumberFilter())
+    logging.getLogger(prefix).addHandler(log_file_handler)
+    return log_file_handler
+
+
+def run_pipeline(options, *, plugin_manager, api=False):
+    # Any changes to options will not take effect for options that are already
+    # bound to function parameters in the pipeline. (For example
+    # options.input_file, options.pdf_renderer are already bound.)
+    if not options.jobs:
+        options.jobs = available_cpu_count()
+    if not plugin_manager:
+        plugin_manager = get_plugin_manager(options.plugins)
+
+    work_folder = Path(mkdtemp(prefix="ocrmypdf.io."))
+    debug_log_handler = None
+    if (
+        (options.keep_temporary_files or options.verbose >= 1)
+        and not os.environ.get('PYTEST_CURRENT_TEST', '')
+        and not api
+    ):
+        # Debug log for command line interface only with verbose output
+        # See https://github.com/pytest-dev/pytest/issues/5502 for why we skip this
+        # when pytest is running
+        debug_log_handler = configure_debug_logging(
+            Path(work_folder) / "debug.log"
+        )  # pragma: no cover
+
+    pikepdf_enable_mmap()
+
+    executor = setup_executor(plugin_manager)
+    try:
+        check_requested_output_file(options)
+        start_input_file, original_filename = create_input_file(options, work_folder)
+
+        # Triage image or pdf
+        origin_pdf = triage(
+            original_filename, start_input_file, work_folder / 'origin.pdf', options
+        )
+
+        # Gather pdfinfo and create context
+        pdfinfo = get_pdfinfo(
+            origin_pdf,
+            executor=executor,
+            detailed_analysis=options.redo_ocr,
+            progbar=options.progress_bar,
+            max_workers=options.jobs if not options.use_threads else 1,  # To help debug
+            check_pages=options.pages,
+        )
+
+        context = PdfContext(options, work_folder, origin_pdf, pdfinfo, plugin_manager)
+
+        # Validate options are okay for this pdf
+        validate_pdfinfo_options(context)
+
+        # Execute the pipeline
+        exec_concurrent(context, executor)
+
+        if options.output_file == '-':
+            log.info("Output sent to stdout")
+        elif (
+            hasattr(options.output_file, 'writable') and options.output_file.writable()
+        ):
+            log.info("Output written to stream")
+        elif samefile(options.output_file, os.devnull):
+            pass  # Say nothing when sending to dev null
+        else:
+            if options.output_type.startswith('pdfa'):
+                pdfa_info = file_claims_pdfa(options.output_file)
+                if pdfa_info['pass']:
+                    log.info(
+                        "Output file is a %s (as expected)", pdfa_info['conformance']
+                    )
+                else:
+                    log.warning(
+                        "Output file is okay but is not PDF/A (seems to be %s)",
+                        pdfa_info['conformance'],
+                    )
+                    return ExitCode.pdfa_conversion_failed
+            if not check_pdf(options.output_file):
+                log.warning('Output file: The generated PDF is INVALID')
+                return ExitCode.invalid_output_pdf
+            report_output_file_size(options, start_input_file, options.output_file)
+
+    except (KeyboardInterrupt if not api else NeverRaise):
+        if options.verbose >= 1:
+            log.exception("KeyboardInterrupt")
+        else:
+            log.error("KeyboardInterrupt")
+        return ExitCode.ctrl_c
+    except (ExitCodeException if not api else NeverRaise) as e:
+        if options.verbose >= 1:
+            log.exception("ExitCodeException")
+        elif str(e):
+            log.error("%s: %s", type(e).__name__, str(e))
+        else:
+            log.error(type(e).__name__)
+        return e.exit_code
+    except (PIL.Image.DecompressionBombError if not api else NeverRaise) as e:
+        log.exception(
+            "A decompression bomb error was encountered while executing the "
+            "pipeline. Use the argument --max-image-mpixels to raise the maximum "
+            "image pixel limit."
+        )
+        return ExitCode.other_error
+    except (Exception if not api else NeverRaise):  # pylint: disable=broad-except
+        log.exception("An exception occurred while executing the pipeline")
+        return ExitCode.other_error
+    finally:
+        if debug_log_handler:
+            try:
+                debug_log_handler.close()
+                log.removeHandler(debug_log_handler)
+            except OSError as e:
+                print(e, file=sys.stderr)
+        cleanup_working_files(work_folder, options)
+
+    return ExitCode.ok

src/ocrmypdf/_validation.py

@@ -0,0 +1,384 @@
+#!/usr/bin/env python3
+# © 2015-17 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import locale
+import logging
+import os
+import sys
+import unicodedata
+from pathlib import Path
+from shutil import copyfileobj
+from typing import List, Set, Tuple
+
+import pikepdf
+import PIL
+
+from ocrmypdf._exec import jbig2enc, pngquant, unpaper
+from ocrmypdf.exceptions import (
+    BadArgsError,
+    InputFileError,
+    MissingDependencyError,
+    OutputFileAccessError,
+)
+from ocrmypdf.helpers import is_file_writable, monotonic, safe_symlink, samefile
+from ocrmypdf.hocrtransform import HOCR_OK_LANGS
+from ocrmypdf.subprocess import check_external_program
+
+# -------------
+# External dependencies
+
+DEFAULT_LANGUAGE = 'eng'  # Enforce English hegemony
+
+log = logging.getLogger(__name__)
+
+
+# --------
+
+
+def check_platform():
+    if os.name == 'nt' and sys.maxsize <= 2 ** 32:  # pragma: no cover
+        # 32-bit interpreter on Windows
+        log.error(
+            "You are running OCRmyPDF in a 32-bit (x86) Python interpreter."
+            "Please use a 64-bit (x86-64) version of Python."
+        )
+
+
+def check_options_languages(options, ocr_engine_languages):
+    if not options.languages:
+        options.languages = {DEFAULT_LANGUAGE}
+        system_lang = locale.getlocale()[0]
+        if system_lang and not system_lang.startswith('en'):
+            log.debug("No language specified; assuming --language %s", DEFAULT_LANGUAGE)
+    if not ocr_engine_languages:
+        return
+    missing_languages = options.languages - ocr_engine_languages
+    if missing_languages:
+        msg = (
+            "OCR engine does not have language data for the following "
+            "requested languages: \n"
+        )
+        msg += '\n'.join(lang for lang in missing_languages)
+        msg += '\nNote: most languages are identified by a 3-digit ISO 639-2 Code'
+        raise MissingDependencyError(msg)
+
+
+def check_options_output(options):
+    is_latin = options.languages.issubset(HOCR_OK_LANGS)
+
+    if options.pdf_renderer.startswith('hocr') and not is_latin:
+        log.warning(
+            "The 'hocr' PDF renderer is known to cause problems with one "
+            "or more of the languages in your document.  Use "
+            "`--pdf-renderer auto` (the default) to avoid this issue."
+        )
+
+    if options.output_type == 'none' and options.output_file != os.devnull:
+        raise BadArgsError(
+            "Since you specified `--pdf-renderer none`, the output file "
+            f"{options.output_file} cannot be produced. Set the output file to "
+            f"{os.devnull} to suppress this message."
+        )
+
+    lossless_reconstruction = False
+    if not any(
+        (
+            options.deskew,
+            options.clean_final,
+            options.force_ocr,
+            options.remove_background,
+        )
+    ):
+        lossless_reconstruction = True
+    options.lossless_reconstruction = lossless_reconstruction
+
+    if not options.lossless_reconstruction and options.redo_ocr:
+        raise BadArgsError(
+            "--redo-ocr is not currently compatible with --deskew, "
+            "--clean-final, and --remove-background"
+        )
+
+
+def check_options_sidecar(options):
+    if options.sidecar == '\0':
+        if options.output_file == '-':
+            raise BadArgsError(
+                "--sidecar filename must be specified when output file is stdout."
+            )
+        elif options.output_file == os.devnull:
+            raise BadArgsError(
+                "--sidecar filename must be specified when output file is /dev/null or NUL."
+            )
+        options.sidecar = options.output_file + '.txt'
+    if options.sidecar == options.input_file or options.sidecar == options.output_file:
+        raise BadArgsError(
+            "--sidecar file must be different from the input and output files"
+        )
+
+
+def check_options_preprocessing(options):
+    if options.clean_final:
+        options.clean = True
+    if options.unpaper_args and not options.clean:
+        raise BadArgsError("--clean is required for --unpaper-args")
+    if options.clean:
+        check_external_program(
+            program='unpaper',
+            package='unpaper',
+            version_checker=unpaper.version,
+            need_version='6.1',
+            required_for=['--clean, --clean-final'],
+        )
+        try:
+            if options.unpaper_args:
+                options.unpaper_args = unpaper.validate_custom_args(
+                    options.unpaper_args
+                )
+        except Exception as e:
+            raise BadArgsError("--unpaper-args: " + str(e)) from e
+
+
+def _pages_from_ranges(ranges: str) -> Set[int]:
+    pages: List[int] = []
+    page_groups = ranges.replace(' ', '').split(',')
+    for g in page_groups:
+        if not g:
+            continue
+        try:
+            start, end = g.split('-')
+        except ValueError:
+            pages.append(int(g) - 1)
+        else:
+            try:
+                new_pages = list(range(int(start) - 1, int(end)))
+                if not new_pages:
+                    raise BadArgsError(
+                        f"invalid page subrange '{start}-{end}'"
+                    ) from None
+                pages.extend(new_pages)
+            except ValueError:
+                raise BadArgsError(f"invalid page subrange '{g}'") from None
+
+    if not pages:
+        raise BadArgsError(
+            f"The string of page ranges '{ranges}' did not contain any recognizable "
+            f"page ranges."
+        )
+
+    if not monotonic(pages):
+        log.warning(
+            "List of pages to process contains duplicate pages, or pages that are "
+            "out of order"
+        )
+    if any(page < 0 for page in pages):
+        raise BadArgsError("pages refers to a page number less than 1")
+
+    log.debug("OCRing only these pages: %s", pages)
+    return set(pages)
+
+
+def check_options_ocr_behavior(options):
+    exclusive_options = sum(
+        (1 if opt else 0)
+        for opt in (options.force_ocr, options.skip_text, options.redo_ocr)
+    )
+    if exclusive_options >= 2:
+        raise BadArgsError("Choose only one of --force-ocr, --skip-text, --redo-ocr.")
+    if options.pages:
+        options.pages = _pages_from_ranges(options.pages)
+
+
+def check_options_optimizing(options):
+    if options.optimize >= 2:
+        check_external_program(
+            program='pngquant',
+            package='pngquant',
+            version_checker=pngquant.version,
+            need_version='2.0.1',
+            required_for='--optimize {2,3}',
+        )
+
+    if options.optimize >= 2:
+        # Although we use JBIG2 for optimize=1, don't nag about it unless the
+        # user is asking for more optimization
+        check_external_program(
+            program='jbig2',
+            package='jbig2enc',
+            version_checker=jbig2enc.version,
+            need_version='0.28',
+            required_for='--optimize {2,3} | --jbig2-lossy',
+            recommended=True if not options.jbig2_lossy else False,
+        )
+
+    if options.optimize == 0 and any(
+        [options.jbig2_lossy, options.png_quality, options.jpeg_quality]
+    ):
+        log.warning(
+            "The arguments --jbig2-lossy, --png-quality, and --jpeg-quality "
+            "will be ignored because --optimize=0."
+        )
+
+
+def check_options_advanced(options):
+    if options.pdfa_image_compression != 'auto' and not options.output_type.startswith(
+        'pdfa'
+    ):
+        log.warning(
+            "--pdfa-image-compression argument only applies when "
+            "--output-type is one of 'pdfa', 'pdfa-1', or 'pdfa-2'"
+        )
+
+
+def check_options_metadata(options):
+    docinfo = [options.title, options.author, options.keywords, options.subject]
+    for s in (m for m in docinfo if m):
+        for c in s:
+            if unicodedata.category(c) == 'Co' or ord(c) >= 0x10000:
+                raise ValueError(
+                    "One of the metadata strings contains "
+                    "an unsupported Unicode character: '{}' (U+{})".format(
+                        c, hex(ord(c))[2:].upper()
+                    )
+                )
+
+
+def check_options_pillow(options):
+    PIL.Image.MAX_IMAGE_PIXELS = int(options.max_image_mpixels * 1_000_000)
+    if PIL.Image.MAX_IMAGE_PIXELS == 0:
+        PIL.Image.MAX_IMAGE_PIXELS = None
+
+
+def _check_options(options, plugin_manager, ocr_engine_languages):
+    check_platform()
+    check_options_languages(options, ocr_engine_languages)
+    check_options_metadata(options)
+    check_options_output(options)
+    check_options_sidecar(options)
+    check_options_preprocessing(options)
+    check_options_ocr_behavior(options)
+    check_options_optimizing(options)
+    check_options_advanced(options)
+    check_options_pillow(options)
+    plugin_manager.hook.check_options(options=options)
+
+
+def check_options(options, plugin_manager):
+    ocr_engine_languages = plugin_manager.hook.get_ocr_engine().languages(options)
+    _check_options(options, plugin_manager, ocr_engine_languages)
+
+
+def create_input_file(options, work_folder: Path) -> Tuple[Path, str]:
+    if options.input_file == '-':
+        # stdin
+        log.info('reading file from standard input')
+        target = work_folder / 'stdin'
+        with open(target, 'wb') as stream_buffer:
+            copyfileobj(sys.stdin.buffer, stream_buffer)
+        return target, "stdin"
+    elif hasattr(options.input_file, 'readable'):
+        if not options.input_file.readable():
+            raise InputFileError("Input file stream is not readable")
+        log.info('reading file from input stream')
+        target = work_folder / 'stream'
+        with open(target, 'wb') as stream_buffer:
+            copyfileobj(options.input_file, stream_buffer)
+        return target, "stream"
+    else:
+        try:
+            target = work_folder / 'origin'
+            safe_symlink(options.input_file, target)
+            return target, os.fspath(options.input_file)
+        except FileNotFoundError:
+            msg = f"File not found - {options.input_file}"
+            if Path('/.dockerenv').exists():  # pragma: no cover
+                msg += (
+                    "\nDocker cannot your working directory unless you "
+                    "explicitly share it with the Docker container and set up"
+                    "permissions correctly.\n"
+                    "You may find it easier to use stdin/stdout:"
+                    "\n"
+                    "\tdocker run -i --rm jbarlow83/ocrmypdf - - <input.pdf >output.pdf\n"
+                )
+            raise InputFileError(msg)
+
+
+def check_requested_output_file(options):
+    if options.output_file == '-':
+        if sys.stdout.isatty():
+            raise BadArgsError(
+                "Output was set to stdout '-' but it looks like stdout "
+                "is connected to a terminal.  Please redirect stdout to a "
+                "file."
+            )
+    elif hasattr(options.output_file, 'writable'):
+        if not options.output_file.writable():
+            raise OutputFileAccessError("Output stream is not writable")
+    elif not is_file_writable(options.output_file):
+        raise OutputFileAccessError(
+            f"Output file location ({options.output_file}) is not a writable file."
+        )
+
+
+def report_output_file_size(options, input_file, output_file):
+    try:
+        output_size = Path(output_file).stat().st_size
+        input_size = Path(input_file).stat().st_size
+    except FileNotFoundError:
+        return  # Outputting to stream or something
+    with pikepdf.open(output_file) as p:
+        # Overhead constants obtained by estimating amount of data added by OCR
+        # PDF/A conversion, and possible XMP metadata addition, with compression
+        FILE_OVERHEAD = 4000
+        OCR_PER_PAGE_OVERHEAD = 3000
+        reasonable_overhead = FILE_OVERHEAD + OCR_PER_PAGE_OVERHEAD * len(p.pages)
+    ratio = output_size / input_size
+    reasonable_ratio = output_size / (input_size + reasonable_overhead)
+    if reasonable_ratio < 1.35 or input_size < 25000:
+        return  # Seems fine
+
+    reasons = []
+    image_preproc = {
+        'deskew',
+        'clean_final',
+        'remove_background',
+        'oversample',
+        'force_ocr',
+    }
+    for arg in image_preproc:
+        if getattr(options, arg, False):
+            reasons.append(
+                f"The argument --{arg.replace('_', '-')} was issued, causing transcoding."
+            )
+
+    if options.optimize == 0:
+        reasons.append("Optimization was disabled.")
+    else:
+        image_optimizers = {
+            'jbig2': jbig2enc.available(),
+            'pngquant': pngquant.available(),
+        }
+        for name, available in image_optimizers.items():
+            if not available:
+                reasons.append(
+                    f"The optional dependency '{name}' was not found, so some image "
+                    f"optimizations could not be attempted."
+                )
+    if options.output_type.startswith('pdfa'):
+        reasons.append("PDF/A conversion was enabled. (Try `--output-type pdf`.)")
+    if options.plugins:
+        reasons.append("Plugins were used.")
+
+    if reasons:
+        explanation = "Possible reasons for this include:\n" + '\n'.join(reasons) + "\n"
+    else:
+        explanation = "No reason for this increase is known.  Please report this issue."
+
+    log.warning(
+        f"The output file size is {ratio:.2f}× larger than the input file.\n"
+        f"{explanation}"
+    )

src/ocrmypdf/_version.py

@@ -0,0 +1,16 @@
+# © 2017 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+try:
+    from importlib_metadata import version as _package_version
+except ImportError:
+    from importlib.metadata import version as _package_version
+
+PROGRAM_NAME = 'ocrmypdf'
+
+# Official PEP 396
+__version__ = _package_version('ocrmypdf')

src/ocrmypdf/api.py

@@ -0,0 +1,350 @@
+# © 2019 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import logging
+import os
+import sys
+import threading
+from enum import IntEnum
+from io import IOBase
+from pathlib import Path
+from typing import AnyStr, BinaryIO, Iterable, Optional, Union
+from warnings import warn
+
+from ocrmypdf._logging import PageNumberFilter, TqdmConsole
+from ocrmypdf._plugin_manager import get_plugin_manager
+from ocrmypdf._sync import run_pipeline
+from ocrmypdf._validation import check_options
+from ocrmypdf.cli import ArgumentParser, get_parser
+from ocrmypdf.helpers import is_iterable_notstr
+
+try:
+    import coloredlogs
+except ModuleNotFoundError:
+    coloredlogs = None
+
+
+StrPath = Union[Path, AnyStr]
+PathOrIO = Union[BinaryIO, StrPath]
+
+_api_lock = threading.Lock()
+
+
+class Verbosity(IntEnum):
+    """Verbosity level for configure_logging."""
+
+    quiet = -1  #: Suppress most messages
+    default = 0  #: Default level of logging
+    debug = 1  #: Output ocrmypdf debug messages
+    debug_all = 2  #: More detailed debugging from ocrmypdf and dependent modules
+
+
+def configure_logging(
+    verbosity: Verbosity,
+    *,
+    progress_bar_friendly: bool = True,
+    manage_root_logger: bool = False,
+    plugin_manager=None,
+):
+    """Set up logging.
+
+    Before calling :func:`ocrmypdf.ocr()`, you can use this function to
+    configure logging if you want ocrmypdf's output to look like the ocrmypdf
+    command line interface. It will register log handlers, log filters, and
+    formatters, configure color logging to standard error, and adjust the log
+    levels of third party libraries. Details of this are fine-tuned and subject
+    to change. The ``verbosity`` argument is equivalent to the argument
+    ``--verbose`` and applies those settings. If you have a wrapper
+    script for ocrmypdf and you want it to be very similar to ocrmypdf, use this
+    function; if you are using ocrmypdf as part of an application that manages
+    its own logging, you probably do not want this function.
+
+    If this function is not called, ocrmypdf will not configure logging, and it
+    is up to the caller of ``ocrmypdf.ocr()`` to set up logging as it wishes using
+    the Python standard library's logging module. If this function is called,
+    the caller may of course make further adjustments to logging.
+
+    Regardless of whether this function is called, ocrmypdf will perform all of
+    its logging under the ``"ocrmypdf"`` logging namespace. In addition,
+    ocrmypdf imports pdfminer, which logs under ``"pdfminer"``. A library user
+    may wish to configure both; note that pdfminer is extremely chatty at the
+    log level ``logging.INFO``.
+
+    This function does not set up the ``debug.log`` log file that the command
+    line interface does at certain verbosity levels. Applications should configure
+    their own debug logging.
+
+    Args:
+        verbosity: Verbosity level.
+        progress_bar_friendly: If True (the default), install a custom log handler
+            that is compatible with progress bars and colored output.
+        manage_root_logger: Configure the process's root logger.
+        plugin_manager: The plugin manager, used for obtaining the custom log handler.
+
+    Returns:
+        The toplevel logger for ocrmypdf (or the root logger, if we are managing it).
+    """
+
+    prefix = '' if manage_root_logger else 'ocrmypdf'
+
+    log = logging.getLogger(prefix)
+    log.setLevel(logging.DEBUG)
+
+    console = None
+    if plugin_manager and progress_bar_friendly:
+        console = plugin_manager.hook.get_logging_console()
+
+    if not console:
+        console = logging.StreamHandler(stream=sys.stderr)
+
+    if verbosity < 0:
+        console.setLevel(logging.ERROR)
+    elif verbosity >= 1:
+        console.setLevel(logging.DEBUG)
+    else:
+        console.setLevel(logging.INFO)
+
+    console.addFilter(PageNumberFilter())
+
+    if verbosity >= 2:
+        fmt = '%(levelname)7s %(name)s -%(pageno)s %(message)s'
+    else:
+        fmt = '%(pageno)s%(message)s'
+
+    use_colors = progress_bar_friendly
+    if not coloredlogs:
+        use_colors = False
+    if use_colors:
+        if os.name == 'nt':
+            use_colors = coloredlogs.enable_ansi_support()
+        if use_colors:
+            use_colors = coloredlogs.terminal_supports_colors()
+    if use_colors:
+        formatter = coloredlogs.ColoredFormatter(fmt=fmt)
+    else:
+        formatter = logging.Formatter(fmt=fmt)
+
+    console.setFormatter(formatter)
+    log.addHandler(console)
+
+    if verbosity <= 1:
+        pdfminer_log = logging.getLogger('pdfminer')
+        pdfminer_log.setLevel(logging.ERROR)
+        pil_log = logging.getLogger('PIL')
+        pil_log.setLevel(logging.INFO)
+
+    if manage_root_logger:
+        logging.captureWarnings(True)
+
+    return log
+
+
+def create_options(
+    *, input_file: PathOrIO, output_file: PathOrIO, parser: ArgumentParser, **kwargs
+):
+    cmdline = []
+    deferred = []
+
+    for arg, val in kwargs.items():
+        if val is None:
+            continue
+
+        # These arguments with special handling for which we bypass
+        # argparse
+        if arg in {'progress_bar', 'plugins'}:
+            deferred.append((arg, val))
+            continue
+
+        cmd_style_arg = arg.replace('_', '-')
+
+        # Booleans are special: add only if True, omit for False
+        if isinstance(val, bool):
+            if val:
+                cmdline.append(f"--{cmd_style_arg}")
+            continue
+
+        if is_iterable_notstr(val):
+            for elem in val:
+                cmdline.append(f"--{cmd_style_arg}")
+                cmdline.append(elem)
+            continue
+
+        # We have a parameter
+        cmdline.append(f"--{cmd_style_arg}")
+        if isinstance(val, (int, float)):
+            cmdline.append(str(val))
+        elif isinstance(val, str):
+            cmdline.append(val)
+        elif isinstance(val, Path):
+            cmdline.append(str(val))
+        else:
+            raise TypeError(f"{arg}: {val} ({type(val)})")
+
+    if isinstance(input_file, (BinaryIO, IOBase)):
+        cmdline.append('stream://input_file')
+    else:
+        cmdline.append(os.fspath(input_file))
+    if isinstance(output_file, (BinaryIO, IOBase)):
+        cmdline.append('stream://output_file')
+    else:
+        cmdline.append(os.fspath(output_file))
+
+    parser._api_mode = True
+    options = parser.parse_args(cmdline)
+    for keyword, val in deferred:
+        setattr(options, keyword, val)
+
+    if options.input_file == 'stream://input_file':
+        options.input_file = input_file
+    if options.output_file == 'stream://output_file':
+        options.output_file = output_file
+
+    return options
+
+
+def ocr(  # pylint: disable=unused-argument
+    input_file: PathOrIO,
+    output_file: PathOrIO,
+    *,
+    language: Iterable[str] = None,
+    image_dpi: int = None,
+    output_type=None,
+    sidecar: Optional[StrPath] = None,
+    jobs: int = None,
+    use_threads: bool = None,
+    title: str = None,
+    author: str = None,
+    subject: str = None,
+    keywords: str = None,
+    rotate_pages: bool = None,
+    remove_background: bool = None,
+    deskew: bool = None,
+    clean: bool = None,
+    clean_final: bool = None,
+    unpaper_args: str = None,
+    oversample: int = None,
+    remove_vectors: bool = None,
+    force_ocr: bool = None,
+    skip_text: bool = None,
+    redo_ocr: bool = None,
+    skip_big: float = None,
+    optimize: int = None,
+    jpg_quality: int = None,
+    png_quality: int = None,
+    jbig2_lossy: bool = None,
+    jbig2_page_group_size: int = None,
+    pages: str = None,
+    max_image_mpixels: float = None,
+    tesseract_config: Iterable[str] = None,
+    tesseract_pagesegmode: int = None,
+    tesseract_oem: int = None,
+    pdf_renderer=None,
+    tesseract_timeout: float = None,
+    rotate_pages_threshold: float = None,
+    pdfa_image_compression=None,
+    user_words: os.PathLike = None,
+    user_patterns: os.PathLike = None,
+    fast_web_view: float = None,
+    plugins: Iterable[StrPath] = None,
+    plugin_manager=None,
+    keep_temporary_files: bool = None,
+    progress_bar: bool = None,
+    **kwargs,
+):
+    """Run OCRmyPDF on one PDF or image.
+
+    For most arguments, see documentation for the equivalent command line parameter.
+    A few specific arguments are discussed here:
+
+    Args:
+        use_threads: Use worker threads instead of processes. This reduces
+            performance but may make debugging easier since it is easier to set
+            breakpoints.
+        input_file: If a :class:`pathlib.Path`, ``str`` or ``bytes``, this is
+            interpreted as file system path to the input file. If the object
+            appears to be a readable stream (with methods such as ``.read()``
+            and ``.seek()``), the object will be read in its entirety and saved to
+            a temporary file. If ``input_file`` is  ``"-"``, standard input will be
+            read.
+        output_file: If a :class:`pathlib.Path`, ``str`` or ``bytes``, this is
+            interpreted as file system path to the output file. If the object
+            appears to be a writable stream (with methods such as ``.write()`` and
+            ``.seek()``), the output will be written to this stream. If
+            ``output_file`` is ``"-"``, the output will be written to ``sys.stdout``
+            (provided that standard output does not seem to be a terminal device).
+            When a stream is used as output, whether via a writable object or
+            ``"-"``, some final validation steps are not performed (we do not read
+            back the stream after it is written).
+    Raises:
+        ocrmypdf.PdfMergeFailedError: If the input PDF is malformed, preventing merging
+            with the OCR layer.
+        ocrmypdf.MissingDependencyError: If a required dependency program is missing or
+            was not found on PATH.
+        ocrmypdf.UnsupportedImageFormatError: If the input file type was an image that
+            could not be read, or some other file type that is not a PDF.
+        ocrmypdf.DpiError: If the input file is an image, but the resolution of the
+            image is not credible (allowing it to proceed would cause poor OCR).
+        ocrmypdf.OutputFileAccessError: If an attempt to write to the intended output
+            file failed.
+        ocrmypdf.PriorOcrFoundError: If the input PDF seems to have OCR or digital
+            text already, and settings did not tell us to proceed.
+        ocrmypdf.InputFileError: Any other problem with the input file.
+        ocrmypdf.SubprocessOutputError: Any error related to executing a subprocess.
+        ocrmypdf.EncryptedPdfERror: If the input PDF is encrypted (password protected).
+            OCRmyPDF does not remove passwords.
+        ocrmypdf.TesseractConfigError: If Tesseract reported its configuration was not
+            valid.
+
+    Returns:
+        :class:`ocrmypdf.ExitCode`
+    """
+    if plugins and plugin_manager:
+        raise ValueError("plugins= and plugin_manager are mutually exclusive")
+
+    if not plugins:
+        plugins = []
+    elif isinstance(plugins, (str, Path)):
+        plugins = [plugins]
+    else:
+        plugins = list(plugins)
+
+    # No new variable names should be assigned until these two steps are run
+    create_options_kwargs = {k: v for k, v in locals().items() if k != 'kwargs'}
+    create_options_kwargs.update(kwargs)
+
+    parser = get_parser()
+    create_options_kwargs['parser'] = parser
+
+    with _api_lock:
+        # We can't allow multiple ocrmypdf.ocr() threads to run in parallel, because
+        # they might install different plugins, and generally speaking we have areas
+        # of code that use global state.
+
+        if not plugin_manager:
+            plugin_manager = get_plugin_manager(plugins)
+        plugin_manager.hook.add_options(parser=parser)  # pylint: disable=no-member
+
+        if 'verbose' in kwargs:
+            warn("ocrmypdf.ocr(verbose=) is ignored. Use ocrmypdf.configure_logging().")
+
+        options = create_options(**create_options_kwargs)
+        check_options(options, plugin_manager)
+        return run_pipeline(options=options, plugin_manager=plugin_manager, api=True)
+
+
+__all__ = [
+    'PageNumberFilter',
+    'TqdmConsole',
+    'Verbosity',
+    'check_options',
+    'configure_logging',
+    'create_options',
+    'get_parser',
+    'get_plugin_manager',
+    'ocr',
+    'run_pipeline',
+]

src/ocrmypdf/builtin_plugins/__init__.py

@@ -0,0 +1,9 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# This file exists only mark builtin_plugins as a package.
+# The plugin manager will not load it, so anything defined here may not be
+# processed as a module.

src/ocrmypdf/builtin_plugins/concurrency.py

@@ -0,0 +1,174 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import logging
+import logging.handlers
+import multiprocessing
+import os
+import queue
+import signal
+import sys
+import threading
+from contextlib import suppress
+from multiprocessing.pool import Pool, ThreadPool
+from typing import Callable, Iterable, Type, Union
+
+from tqdm import tqdm
+
+from ocrmypdf import Executor, hookimpl
+from ocrmypdf._logging import TqdmConsole
+from ocrmypdf.exceptions import InputFileError
+from ocrmypdf.helpers import remove_all_log_handlers
+
+ProcessPool = Pool
+Queue = Union[multiprocessing.Queue, queue.Queue]
+UserInit = Callable[[], None]
+WorkerInit = Callable[[Queue, UserInit, int], None]
+
+
+def log_listener(q: Queue):
+    """Listen to the worker processes and forward the messages to logging
+
+    For simplicity this is a thread rather than a process. Only one process
+    should actually write to sys.stderr or whatever we're using, so if this is
+    made into a process the main application needs to be directed to it.
+
+    See https://docs.python.org/3/howto/logging-cookbook.html#logging-to-a-single-file-from-multiple-processes
+    """
+
+    while True:
+        try:
+            record = q.get()
+            if record is None:
+                break
+            logger = logging.getLogger(record.name)
+            logger.handle(record)
+        except Exception:  # pylint: disable=broad-except
+            import traceback  # pylint: disable=import-outside-toplevel
+
+            print("Logging problem", file=sys.stderr)
+            traceback.print_exc(file=sys.stderr)
+
+
+def process_sigbus(*args):
+    raise InputFileError("A worker process lost access to an input file")
+
+
+def process_init(q: Queue, user_init: UserInit, loglevel) -> None:
+    """Initialize a process pool worker"""
+
+    # Ignore SIGINT (our parent process will kill us gracefully)
+    signal.signal(signal.SIGINT, signal.SIG_IGN)
+
+    # Install SIGBUS handler (so our parent process can abort somewhat gracefully)
+    with suppress(AttributeError):  # Windows and Cygwin do not have SIGBUS
+        # Windows and Cygwin do not have pthread_sigmask or SIGBUS
+        signal.signal(signal.SIGBUS, process_sigbus)
+
+    # Remove any log handlers that belong to the parent process
+    root = logging.getLogger()
+    remove_all_log_handlers(root)
+
+    # Set up our single log handler to forward messages to the parent
+    root.setLevel(loglevel)
+    root.addHandler(logging.handlers.QueueHandler(q))
+
+    user_init()
+    return
+
+
+def thread_init(q: Queue, user_init: UserInit, loglevel) -> None:
+    # As a thread, block SIGBUS so the main thread deals with it...
+    with suppress(AttributeError):
+        signal.pthread_sigmask(signal.SIG_BLOCK, {signal.SIGBUS})
+
+    user_init()
+    return
+
+
+class StandardExecutor(Executor):
+    def _execute(
+        self,
+        *,
+        use_threads: bool,
+        max_workers: int,
+        tqdm_kwargs: dict,
+        worker_initializer: Callable,
+        task: Callable,
+        task_arguments: Iterable,
+        task_finished: Callable,
+    ):
+        if use_threads:
+            log_queue: Queue = queue.Queue(-1)
+            pool_class: Type[Pool] = ThreadPool
+            initializer: WorkerInit = thread_init
+        else:
+            log_queue = multiprocessing.Queue(-1)
+            pool_class = ProcessPool
+            initializer = process_init
+
+        # Regardless of whether we use_threads for worker processes, the log_listener
+        # must be a thread. Make sure we create the listener after the worker pool,
+        # so that it does not get forked into the workers.
+        listener = threading.Thread(target=log_listener, args=(log_queue,))
+        listener.start()
+
+        with self.pbar_class(**tqdm_kwargs) as pbar:
+            pool = pool_class(
+                processes=max_workers,
+                initializer=initializer,
+                initargs=(log_queue, worker_initializer, logging.getLogger("").level),
+            )
+            try:
+                results = pool.imap_unordered(task, task_arguments)
+                for result in results:
+                    if task_finished:
+                        task_finished(result, pbar)
+                    else:
+                        pbar.update()
+            except KeyboardInterrupt:
+                # Terminate pool so we exit instantly
+                pool.terminate()
+                # Don't try listener.join() here, will deadlock
+                raise
+            except Exception:
+                if not os.environ.get("PYTEST_CURRENT_TEST", ""):
+                    # Unless inside pytest, exit immediately because no one wants
+                    # to wait for child processes to finalize results that will be
+                    # thrown away. Inside pytest, we want child processes to exit
+                    # cleanly so that they output an error messages or coverage data
+                    # we need from them.
+                    pool.terminate()
+                raise
+            finally:
+                # Terminate log listener
+                log_queue.put_nowait(None)
+                pool.close()
+                pool.join()
+
+        listener.join()
+
+
+@hookimpl
+def get_executor(progressbar_class):
+    return StandardExecutor(pbar_class=progressbar_class)
+
+
+@hookimpl
+def get_progressbar_class():
+    return tqdm
+
+
+@hookimpl
+def get_logging_console():
+    return logging.StreamHandler(stream=TqdmConsole(sys.stderr))

src/ocrmypdf/builtin_plugins/default_filters.py

@@ -0,0 +1,14 @@
+# © 2021 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from ocrmypdf import hookimpl
+
+
+@hookimpl
+def filter_pdf_page(
+    page, image_filename, output_pdf
+):  # pylint: disable=unused-argument
+    return output_pdf

src/ocrmypdf/builtin_plugins/ghostscript.py

@@ -0,0 +1,99 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import logging
+
+from ocrmypdf import hookimpl
+from ocrmypdf._exec import ghostscript
+from ocrmypdf._validation import HOCR_OK_LANGS
+from ocrmypdf.exceptions import MissingDependencyError
+from ocrmypdf.subprocess import check_external_program
+
+log = logging.getLogger(__name__)
+
+
+@hookimpl
+def check_options(options):
+    gs_version = ghostscript.version()
+    check_external_program(
+        program='gs',
+        package='ghostscript',
+        version_checker=gs_version,
+        need_version='9.15',  # limited by Travis CI / Ubuntu 14.04 backports
+    )
+    if gs_version in ('9.24', '9.51'):
+        raise MissingDependencyError(
+            f"Ghostscript {gs_version} contains serious regressions and is not "
+            "supported. Please upgrade to a newer version, or downgrade to the "
+            "previous version."
+        )
+
+    # We have these constraints to check for.
+    # 1. Ghostscript < 9.20 mangles multibyte Unicode
+    # 2. hocr doesn't work on non-Latin languages (so don't select it)
+    is_latin = options.languages.issubset(HOCR_OK_LANGS)
+    if gs_version < '9.20' and options.output_type != 'pdf' and not is_latin:
+        # https://bugs.ghostscript.com/show_bug.cgi?id=696874
+        # Ghostscript < 9.20 fails to encode multibyte characters properly
+        log.warning(
+            f"The installed version of Ghostscript ({gs_version}) does not work "
+            "correctly with the OCR languages you specified. Use --output-type pdf or "
+            "upgrade to Ghostscript 9.20 or later to avoid this issue."
+        )
+
+    if options.output_type == 'pdfa':
+        options.output_type = 'pdfa-2'
+
+    if options.output_type == 'pdfa-3' and ghostscript.version() < '9.19':
+        raise MissingDependencyError(
+            "--output-type pdfa-3 requires Ghostscript 9.19 or later"
+        )
+
+
+@hookimpl
+def rasterize_pdf_page(
+    input_file,
+    output_file,
+    raster_device,
+    raster_dpi,
+    pageno,
+    page_dpi,
+    rotation,
+    filter_vector,
+):
+    ghostscript.rasterize_pdf(
+        input_file,
+        output_file,
+        raster_device=raster_device,
+        raster_dpi=raster_dpi,
+        pageno=pageno,
+        page_dpi=page_dpi,
+        rotation=rotation,
+        filter_vector=filter_vector,
+    )
+    return output_file
+
+
+@hookimpl
+def generate_pdfa(
+    pdf_pages,
+    pdfmark,
+    output_file,
+    compression,
+    pdf_version,
+    pdfa_part,
+    progressbar_class,
+):
+    ghostscript.generate_pdfa(
+        pdf_pages=[*pdf_pages, pdfmark],
+        output_file=output_file,
+        compression=compression,
+        pdf_version=pdf_version,
+        pdfa_part=pdfa_part,
+        progressbar_class=progressbar_class,
+    )
+    return output_file

src/ocrmypdf/builtin_plugins/tesseract_ocr.py

@@ -0,0 +1,187 @@
+# © 2020 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import logging
+import os
+
+from ocrmypdf import hookimpl
+from ocrmypdf._exec import tesseract
+from ocrmypdf.cli import numeric
+from ocrmypdf.helpers import clamp
+from ocrmypdf.pluginspec import OcrEngine
+from ocrmypdf.subprocess import check_external_program
+
+log = logging.getLogger(__name__)
+
+
+@hookimpl
+def add_options(parser):
+    tess = parser.add_argument_group("Tesseract", "Advanced control of Tesseract OCR")
+    tess.add_argument(
+        '--tesseract-config',
+        action='append',
+        metavar='CFG',
+        default=[],
+        help="Additional Tesseract configuration files -- see documentation",
+    )
+    tess.add_argument(
+        '--tesseract-pagesegmode',
+        action='store',
+        type=int,
+        metavar='PSM',
+        choices=range(0, 14),
+        help="Set Tesseract page segmentation mode (see tesseract --help)",
+    )
+    tess.add_argument(
+        '--tesseract-oem',
+        action='store',
+        type=int,
+        metavar='MODE',
+        choices=range(0, 4),
+        help=(
+            "Set Tesseract 4.0 OCR engine mode: "
+            "0 - original Tesseract only; "
+            "1 - neural nets LSTM only; "
+            "2 - Tesseract + LSTM; "
+            "3 - default."
+        ),
+    )
+    tess.add_argument(
+        '--tesseract-timeout',
+        default=180.0,
+        type=numeric(float, 0),
+        metavar='SECONDS',
+        help='Give up on OCR after the timeout, but copy the preprocessed page '
+        'into the final output',
+    )
+    tess.add_argument(
+        '--user-words',
+        metavar='FILE',
+        help="Specify the location of the Tesseract user words file. This is a "
+        "list of words Tesseract should consider while performing OCR in "
+        "addition to its standard language dictionaries. This can improve "
+        "OCR quality especially for specialized and technical documents.",
+    )
+    tess.add_argument(
+        '--user-patterns',
+        metavar='FILE',
+        help="Specify the location of the Tesseract user patterns file.",
+    )
+
+
+@hookimpl
+def check_options(options):
+    check_external_program(
+        program='tesseract',
+        package={'linux': 'tesseract-ocr'},
+        version_checker=tesseract.version,
+        need_version='4.0.0-beta.1',  # using backport for Travis CI
+        version_parser=tesseract.TesseractVersion,
+    )
+
+    # Decide on what renderer to use
+    if options.pdf_renderer == 'auto':
+        options.pdf_renderer = 'sandwich'
+
+    if not tesseract.has_user_words() and (options.user_words or options.user_patterns):
+        log.warning(
+            "Tesseract 4.0 ignores --user-words and --user-patterns, so these "
+            "arguments have no effect."
+        )
+    if options.tesseract_pagesegmode in (0, 2):
+        log.warning(
+            "The --tesseract-pagesegmode argument you select will disable OCR. "
+            "This may cause processing to fail."
+        )
+
+
+@hookimpl
+def validate(pdfinfo, options):
+    # Tesseract 4.x can be multithreaded, and we also run multiple workers. We want
+    # to manage how many threads it uses to avoid creating total threads than cores.
+    # Performance testing shows we're better off
+    # parallelizing ocrmypdf and forcing Tesseract to be single threaded, which we
+    # get by setting the envvar OMP_THREAD_LIMIT to 1. But if the page count of the
+    # input file is small, then we allow Tesseract to use threads, subject to the
+    # constraint: (ocrmypdf workers) * (tesseract threads) <= max_workers.
+    # As of Tesseract 4.1, 3 threads is the most effective on a 4 core/8 thread system.
+    if not os.environ.get('OMP_THREAD_LIMIT', '').isnumeric():
+        tess_threads = clamp(options.jobs // len(pdfinfo), 1, 3)
+        os.environ['OMP_THREAD_LIMIT'] = str(tess_threads)
+    else:
+        tess_threads = int(os.environ['OMP_THREAD_LIMIT'])
+    log.debug("Using Tesseract OpenMP thread limit %d", tess_threads)
+
+
+class TesseractOcrEngine(OcrEngine):
+    @staticmethod
+    def version():
+        return tesseract.version()
+
+    @staticmethod
+    def creator_tag(options):
+        tag = '-PDF' if options.pdf_renderer == 'sandwich' else ''
+        return f"Tesseract OCR{tag} {TesseractOcrEngine.version()}"
+
+    def __str__(self):
+        return f"Tesseract OCR {TesseractOcrEngine.version()}"
+
+    @staticmethod
+    def languages(options):
+        return tesseract.get_languages()
+
+    @staticmethod
+    def get_orientation(input_file, options):
+        return tesseract.get_orientation(
+            input_file,
+            engine_mode=options.tesseract_oem,
+            timeout=options.tesseract_timeout,
+        )
+
+    @staticmethod
+    def get_deskew(input_file, options) -> float:
+        return tesseract.get_deskew(
+            input_file,
+            languages=options.languages,
+            engine_mode=options.tesseract_oem,
+            timeout=options.tesseract_timeout,
+        )
+
+    @staticmethod
+    def generate_hocr(input_file, output_hocr, output_text, options):
+        tesseract.generate_hocr(
+            input_file=input_file,
+            output_hocr=output_hocr,
+            output_text=output_text,
+            languages=options.languages,
+            engine_mode=options.tesseract_oem,
+            tessconfig=options.tesseract_config,
+            timeout=options.tesseract_timeout,
+            pagesegmode=options.tesseract_pagesegmode,
+            user_words=options.user_words,
+            user_patterns=options.user_patterns,
+        )
+
+    @staticmethod
+    def generate_pdf(input_file, output_pdf, output_text, options):
+        tesseract.generate_pdf(
+            input_file=input_file,
+            output_pdf=output_pdf,
+            output_text=output_text,
+            languages=options.languages,
+            engine_mode=options.tesseract_oem,
+            tessconfig=options.tesseract_config,
+            timeout=options.tesseract_timeout,
+            pagesegmode=options.tesseract_pagesegmode,
+            user_words=options.user_words,
+            user_patterns=options.user_patterns,
+        )
+
+
+@hookimpl
+def get_ocr_engine():
+    return TesseractOcrEngine()

src/ocrmypdf/cli.py

@@ -0,0 +1,483 @@
+# © 2015-19 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import argparse
+from typing import Any, Callable, Optional, TypeVar
+
+from ocrmypdf._version import PROGRAM_NAME as _PROGRAM_NAME
+from ocrmypdf._version import __version__ as _VERSION
+
+T = TypeVar('T')
+
+
+def numeric(
+    basetype: Callable[[Any], T], min_: Optional[T] = None, max_: Optional[T] = None
+):
+    """Validator for numeric params"""
+    min_ = basetype(min_) if min_ is not None else None
+    max_ = basetype(max_) if max_ is not None else None
+
+    def _numeric(string):
+        value = basetype(string)
+        if (min_ is not None and value < min_) or (max_ is not None and value > max_):
+            msg = f"{string!r} not in valid range {(min_, max_)!r}"
+            raise argparse.ArgumentTypeError(msg)
+        return value
+
+    _numeric.__name__ = basetype.__name__
+    return _numeric
+
+
+class ArgumentParser(argparse.ArgumentParser):
+    """Override parser's default behavior of calling sys.exit()
+
+    https://stackoverflow.com/questions/5943249/python-argparse-and-controlling-overriding-the-exit-status-code
+    """
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._api_mode = False
+
+    def error(self, message):
+        if not self._api_mode:
+            super().error(message)
+            return
+        raise ValueError(message)
+
+
+class LanguageSetAction(argparse.Action):
+    def __init__(self, option_strings, dest, default=None, **kwargs):
+        if default is None:
+            default = set()
+        super().__init__(option_strings, dest, default=default, **kwargs)
+
+    def __call__(self, parser, namespace, values, option_string=None):
+        dest = getattr(namespace, self.dest)
+        if '+' in values:
+            dest.update(lang for lang in values.split('+'))
+        else:
+            dest.add(values)
+
+
+def get_parser():
+    parser = ArgumentParser(
+        prog=_PROGRAM_NAME,
+        allow_abbrev=True,
+        fromfile_prefix_chars='@',
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        description="""\
+Generates a searchable PDF or PDF/A from a regular PDF.
+
+OCRmyPDF rasterizes each page of the input PDF, optionally corrects page
+rotation and performs image processing, runs the Tesseract OCR engine on the
+image, and then creates a PDF from the OCR information.
+""",
+        epilog="""\
+OCRmyPDF attempts to keep the output file at about the same size.  If a file
+contains losslessly compressed images, and images in the output file will be
+losslessly compressed as well.
+
+PDF is a page description file that attempts to preserve a layout exactly.
+A PDF can contain vector objects (such as text or lines) and raster objects
+(images).  A page might have multiple images.  OCRmyPDF is prepared to deal
+with the wide variety of PDFs that exist in the wild.
+
+When a PDF page contains text, OCRmyPDF assumes that the page has already
+been OCRed or is a "born digital" page that should not be OCRed.  The default
+behavior is to exit in this case without producing a file.  You can use the
+option --skip-text to ignore pages with text, or --force-ocr to rasterize
+all objects on the page and produce an image-only PDF as output.
+
+    ocrmypdf --skip-text file_with_some_text_pages.pdf output.pdf
+
+    ocrmypdf --force-ocr word_document.pdf output.pdf
+
+If you are concerned about long-term archiving of PDFs, use the default option
+--output-type pdfa which converts the PDF to a standardized PDF/A-2b.  This
+removes some features from the PDF such as Javascript or forms. If you want to
+minimize the number of changes made to your PDF, use --output-type pdf.
+
+If OCRmyPDF is given an image file as input, it will attempt to convert the
+image to a PDF before processing.  For more control over the conversion of
+images to PDF, use the Python package img2pdf or other image to PDF software.
+
+For example, this command uses img2pdf to convert all .png files beginning
+with the 'page' prefix to a PDF, fitting each image on A4-sized paper, and
+sending the result to OCRmyPDF through a pipe.
+
+    img2pdf --pagesize A4 page*.png | ocrmypdf - myfile.pdf
+
+Online documentation is located at:
+    https://ocrmypdf.readthedocs.io/en/latest/introduction.html
+
+""",
+    )
+
+    parser.add_argument(
+        'input_file',
+        metavar="input_pdf_or_image",
+        help="PDF file containing the images to be OCRed (or '-' to read from "
+        "standard input)",
+    )
+    parser.add_argument(
+        'output_file',
+        metavar="output_pdf",
+        help="Output searchable PDF file (or '-' to write to standard output). "
+        "Existing files will be ovewritten. If same as input file, the "
+        "input file will be updated only if processing is successful.",
+    )
+    parser.add_argument(
+        '-l',
+        '--language',
+        dest='languages',
+        action=LanguageSetAction,
+        help="Language(s) of the file to be OCRed (see tesseract --list-langs for "
+        "all language packs installed in your system). Use -l eng+deu for "
+        "multiple languages.",
+    )
+    parser.add_argument(
+        '--image-dpi',
+        metavar='DPI',
+        type=int,
+        help="For input image instead of PDF, use this DPI instead of file's.",
+    )
+    parser.add_argument(
+        '--output-type',
+        choices=['pdfa', 'pdf', 'pdfa-1', 'pdfa-2', 'pdfa-3', 'none'],
+        default='pdfa',
+        help="Choose output type. 'pdfa' creates a PDF/A-2b compliant file for "
+        "long term archiving (default, recommended) but may not suitable "
+        "for users who want their file altered as little as possible. 'pdfa' "
+        "also has problems with full Unicode text. 'pdf' attempts to "
+        "preserve file contents as much as possible. 'pdf-a1' creates a "
+        "PDF/A1-b file. 'pdf-a2' is equivalent to 'pdfa'. 'pdf-a3' creates a "
+        "PDF/A3-b file. 'none' will produce no output, which may be helpful if "
+        "only the --sidecar is desired.",
+    )
+
+    # Use null string '\0' as sentinel to indicate the user supplied no argument,
+    # since that is the only invalid character for filepaths on all platforms
+    # bool('\0') is True in Python
+    parser.add_argument(
+        '--sidecar',
+        nargs='?',
+        const='\0',
+        default=None,
+        metavar='FILE',
+        help="Generate sidecar text files that contain the same text recognized "
+        "by Tesseract. This may be useful for building a OCR text database. "
+        "If FILE is omitted, the sidecar file be named {output_file}.txt; the next "
+        "argument must NOT be the name of the input PDF. "
+        "If FILE is set to '-', the sidecar is written to stdout (a "
+        "convenient way to preview OCR quality). The output file and sidecar "
+        "may not both use stdout at the same time.",
+    )
+
+    parser.add_argument(
+        '--version',
+        action='version',
+        version=_VERSION,
+        help="Print program version and exit",
+    )
+
+    jobcontrol = parser.add_argument_group("Job control options")
+    jobcontrol.add_argument(
+        '-j',
+        '--jobs',
+        metavar='N',
+        type=numeric(int, 0, 256),
+        help="Use up to N CPU cores simultaneously (default: use all).",
+    )
+    jobcontrol.add_argument(
+        '-q', '--quiet', action='store_true', help="Suppress INFO messages"
+    )
+    jobcontrol.add_argument(
+        '-v',
+        '--verbose',
+        type=numeric(int, 0, 2),
+        default=0,
+        const=1,
+        nargs='?',
+        help="Print more verbose messages for each additional verbose level. Use "
+        "`-v 1` typically for much more detailed logging. Higher numbers "
+        "are probably only useful in debugging.",
+    )
+    jobcontrol.add_argument(
+        '--no-progress-bar',
+        action='store_false',
+        dest='progress_bar',
+        help=argparse.SUPPRESS,
+    )
+    jobcontrol.add_argument(
+        '--use-threads', action='store_true', help=argparse.SUPPRESS
+    )
+
+    metadata = parser.add_argument_group(
+        "Metadata options",
+        "Set output PDF/A metadata (default: copy input document's metadata)",
+    )
+    metadata.add_argument(
+        '--title', type=str, help="Set document title (place multiple words in quotes)"
+    )
+    metadata.add_argument('--author', type=str, help="Set document author")
+    metadata.add_argument(
+        '--subject', type=str, help="Set document subject description"
+    )
+    metadata.add_argument('--keywords', type=str, help="Set document keywords")
+
+    preprocessing = parser.add_argument_group(
+        "Image preprocessing options",
+        "Options to improve the quality of the final PDF and OCR",
+    )
+    preprocessing.add_argument(
+        '-r',
+        '--rotate-pages',
+        action='store_true',
+        help="Automatically rotate pages based on detected text orientation",
+    )
+    preprocessing.add_argument(
+        '--remove-background',
+        action='store_true',
+        help="Attempt to remove background from gray or color pages, setting it "
+        "to white ",
+    )
+    preprocessing.add_argument(
+        '-d',
+        '--deskew',
+        action='store_true',
+        help="Deskew each page before performing OCR",
+    )
+    preprocessing.add_argument(
+        '-c',
+        '--clean',
+        action='store_true',
+        help="Clean pages from scanning artifacts before performing OCR, and send "
+        "the cleaned page to OCR, but do not include the cleaned page in "
+        "the output",
+    )
+    preprocessing.add_argument(
+        '-i',
+        '--clean-final',
+        action='store_true',
+        help="Clean page as above, and incorporate the cleaned image in the final "
+        "PDF.  Might remove desired content.",
+    )
+    preprocessing.add_argument(
+        '--unpaper-args',
+        type=str,
+        default=None,
+        help="A quoted string of arguments to pass to unpaper. Requires --clean. "
+        "Example: --unpaper-args '--layout double'.",
+    )
+    preprocessing.add_argument(
+        '--oversample',
+        metavar='DPI',
+        type=numeric(int, 0, 5000),
+        default=0,
+        help="Oversample images to at least the specified DPI, to improve OCR "
+        "results slightly",
+    )
+    preprocessing.add_argument(
+        '--remove-vectors',
+        action='store_true',
+        help="EXPERIMENTAL. Mask out any vector objects in the PDF so that they "
+        "will not be included in OCR. This can eliminate false characters.",
+    )
+
+    ocrsettings = parser.add_argument_group("OCR options", "Control how OCR is applied")
+    ocrsettings.add_argument(
+        '-f',
+        '--force-ocr',
+        action='store_true',
+        help="Rasterize any text or vector objects on each page, apply OCR, and "
+        "save the rastered output (this rewrites the PDF)",
+    )
+    ocrsettings.add_argument(
+        '-s',
+        '--skip-text',
+        action='store_true',
+        help="Skip OCR on any pages that already contain text, but include the "
+        "page in final output; useful for PDFs that contain a mix of "
+        "images, text pages, and/or previously OCRed pages",
+    )
+    ocrsettings.add_argument(
+        '--redo-ocr',
+        action='store_true',
+        help="Attempt to detect and remove the hidden OCR layer from files that "
+        "were previously OCRed with OCRmyPDF or another program. Apply OCR "
+        "to text found in raster images. Existing visible text objects will "
+        "not be changed. If there is no existing OCR, OCR will be added.",
+    )
+    ocrsettings.add_argument(
+        '--skip-big',
+        type=numeric(float, 0, 5000),
+        metavar='MPixels',
+        help="Skip OCR on pages larger than the specified amount of megapixels, "
+        "but include skipped pages in final output",
+    )
+
+    optimizing = parser.add_argument_group(
+        "Optimization options", "Control how the PDF is optimized after OCR"
+    )
+    optimizing.add_argument(
+        '-O',
+        '--optimize',
+        type=int,
+        choices=range(0, 4),
+        default=1,
+        help=(
+            "Control how PDF is optimized after processing:"
+            "0 - do not optimize; "
+            "1 - do safe, lossless optimizations (default); "
+            "2 - do lossy JPEG and JPEG2000 optimizations; "
+            "3 - do more aggressive lossy JPEG and JPEG2000 optimizations. "
+            "To enable lossy JBIG2, see --jbig2-lossy."
+        ),
+    )
+    optimizing.add_argument(
+        '--jpeg-quality',
+        type=numeric(int, 0, 100),
+        default=0,
+        metavar='Q',
+        help=(
+            "Adjust JPEG quality level for JPEG optimization. "
+            "100 is best quality and largest output size; "
+            "1 is lowest quality and smallest output; "
+            "0 uses the default."
+        ),
+    )
+    optimizing.add_argument(
+        '--jpg-quality',
+        type=numeric(int, 0, 100),
+        default=0,
+        metavar='Q',
+        dest='jpeg_quality',
+        help=argparse.SUPPRESS,  # Alias for --jpeg-quality
+    )
+    optimizing.add_argument(
+        '--png-quality',
+        type=numeric(int, 0, 100),
+        default=0,
+        metavar='Q',
+        help=(
+            "Adjust PNG quality level to use when quantizing PNGs. "
+            "Values have same meaning as with --jpeg-quality"
+        ),
+    )
+    optimizing.add_argument(
+        '--jbig2-lossy',
+        action='store_true',
+        help=(
+            "Enable JBIG2 lossy mode (better compression, not suitable for some "
+            "use cases - see documentation). Only takes effect if --optimize 1 or "
+            "higher is also enabled."
+        ),
+    )
+    optimizing.add_argument(
+        '--jbig2-page-group-size',
+        type=numeric(int, 1, 10000),
+        default=0,
+        metavar='N',
+        # Adjust number of pages to consider at once for JBIG2 compression
+        help=argparse.SUPPRESS,
+    )
+
+    advanced = parser.add_argument_group(
+        "Advanced", "Advanced options to control OCRmyPDF"
+    )
+    advanced.add_argument(
+        '--pages',
+        type=str,
+        help=(
+            "Limit OCR to the specified pages (ranges or comma separated), "
+            "skipping others"
+        ),
+    )
+    advanced.add_argument(
+        '--max-image-mpixels',
+        action='store',
+        type=numeric(float, 0),
+        metavar='MPixels',
+        help="Set maximum number of pixels to unpack before treating an image as a "
+        "decompression bomb",
+        default=128.0,
+    )
+    advanced.add_argument(
+        '--pdf-renderer',
+        choices=['auto', 'hocr', 'sandwich', 'hocrdebug'],
+        default='auto',
+        help="Choose OCR PDF renderer - the default option is to let OCRmyPDF "
+        "choose.  See documentation for discussion.",
+    )
+    advanced.add_argument(
+        '--rotate-pages-threshold',
+        default=14.0,
+        type=numeric(float, 0, 1000),
+        metavar='CONFIDENCE',
+        help="Only rotate pages when confidence is above this value (arbitrary "
+        "units reported by tesseract)",
+    )
+    advanced.add_argument(
+        '--pdfa-image-compression',
+        choices=['auto', 'jpeg', 'lossless'],
+        default='auto',
+        help="Specify how to compress images in the output PDF/A. 'auto' lets "
+        "OCRmyPDF decide.  'jpeg' changes all grayscale and color images to "
+        "JPEG compression.  'lossless' uses PNG-style lossless compression "
+        "for all images.  Monochrome images are always compressed using a "
+        "lossless codec.  Compression settings "
+        "are applied to all pages, including those for which OCR was "
+        "skipped.  Not supported for --output-type=pdf ; that setting "
+        "preserves the original compression of all images.",
+    )
+    advanced.add_argument(
+        '--fast-web-view',
+        type=numeric(float, 0),
+        default=1.0,
+        metavar="MEGABYTES",
+        help="If the size of file is more than this threshold (in MB), then "
+        "linearize the PDF for fast web viewing. This allows the PDF to be "
+        "displayed before it is fully downloaded in web browsers, but increases "
+        "the space required slightly. By default we skip this for small files "
+        "which do not benefit. If the threshold is 0 it will be apply to all files. "
+        "Set the threshold very high to disable.",
+    )
+    advanced.add_argument(
+        '--plugin',
+        dest='plugins',
+        action='append',
+        default=[],
+        help="Name of plugin to import. Argument may be issued multiple times to "
+        "import multiple plugins. Plugins may be specified as module names in "
+        "Python syntax, provided they are installed in the same Python (virtual) "
+        "environment as ocrmypdf; or you may give the path to the Python file that "
+        "contains the plugin. Plugins must conform to the specification in the "
+        "OCRmyPDF documentation.",
+    )
+
+    debugging = parser.add_argument_group(
+        "Debugging", "Arguments to help with troubleshooting and debugging"
+    )
+    debugging.add_argument(
+        '-k',
+        '--keep-temporary-files',
+        action='store_true',
+        help="Keep temporary files (helpful for debugging)",
+    )
+    return parser
+
+
+plugins_only_parser = ArgumentParser(
+    prog=_PROGRAM_NAME, fromfile_prefix_chars='@', add_help=False, allow_abbrev=False
+)
+plugins_only_parser.add_argument(
+    '--plugin',
+    dest='plugins',
+    action='append',
+    default=[],
+    help="Name of plugin to import.",
+)

src/ocrmypdf/data/__init__.py

@@ -0,0 +1,8 @@
+# © 2021 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+"""Data files used to generate certain PDFs."""

src/ocrmypdf/exceptions.py

@@ -0,0 +1,104 @@
+# © 2016 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+from enum import IntEnum
+from textwrap import dedent
+
+
+class ExitCode(IntEnum):
+    ok = 0
+    bad_args = 1
+    input_file = 2
+    missing_dependency = 3
+    invalid_output_pdf = 4
+    file_access_error = 5
+    already_done_ocr = 6
+    child_process_error = 7
+    encrypted_pdf = 8
+    invalid_config = 9
+    pdfa_conversion_failed = 10
+    other_error = 15
+    ctrl_c = 130
+
+
+class ExitCodeException(Exception):
+    exit_code = ExitCode.other_error
+    message = ""
+
+    def __str__(self):
+        super_msg = super().__str__()  # Don't do str(super())
+        if self.message:
+            return self.message.format(super_msg)
+        return super_msg
+
+
+class BadArgsError(ExitCodeException):
+    exit_code = ExitCode.bad_args
+
+
+class PdfMergeFailedError(ExitCodeException):
+    exit_code = ExitCode.input_file
+    message = dedent(
+        '''\
+        Failed to merge PDF image layer with OCR layer
+
+        Usually this happens because the input PDF file is malformed and
+        ocrmypdf cannot automatically correct the problem on its own.
+
+        Try using
+            ocrmypdf --pdf-renderer sandwich  [..other args..]
+        '''
+    )
+
+
+class MissingDependencyError(ExitCodeException):
+    exit_code = ExitCode.missing_dependency
+
+
+class UnsupportedImageFormatError(ExitCodeException):
+    exit_code = ExitCode.input_file
+
+
+class DpiError(ExitCodeException):
+    exit_code = ExitCode.input_file
+
+
+class OutputFileAccessError(ExitCodeException):
+    exit_code = ExitCode.file_access_error
+
+
+class PriorOcrFoundError(ExitCodeException):
+    exit_code = ExitCode.already_done_ocr
+
+
+class InputFileError(ExitCodeException):
+    exit_code = ExitCode.input_file
+
+
+class SubprocessOutputError(ExitCodeException):
+    exit_code = ExitCode.child_process_error
+
+
+class EncryptedPdfError(ExitCodeException):
+    exit_code = ExitCode.encrypted_pdf
+    message = dedent(
+        '''\
+        Input PDF is encrypted. The encryption must be removed to
+        perform OCR.
+
+        For information about this PDF's security use
+            qpdf --show-encryption infilename
+
+        You can remove the encryption using
+            qpdf --decrypt [--password=[password]] infilename
+        '''
+    )
+
+
+class TesseractConfigError(ExitCodeException):
+    exit_code = ExitCode.invalid_config
+    message = "Error occurred while parsing a Tesseract configuration file"

src/ocrmypdf/extra_plugins/semfree.py

@@ -0,0 +1,195 @@
+# © 2021 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+"""Semaphore-free alternate executor.
+
+There are two popular environments that do not fully support the standard Python
+multiprocessing module: AWS Lambda, and Termux (a terminal emulator for Android).
+
+This alternate executor divvies up work among worker processes before processing,
+rather than having each worker consume work from a shared queue when they finish
+their task. This means workers have no need to coordinate with each other. Each
+worker communicates only with the main process.
+
+This is not without drawbacks. If the tasks are not "even" in size, which cannot
+be guaranteed, some workers may end up with too much work while others are idle.
+It is less efficient than the standard implementation, so not th edefault.
+"""
+
+import logging
+import logging.handlers
+import signal
+from contextlib import suppress
+from enum import Enum, auto
+from itertools import islice, repeat, takewhile, zip_longest
+from multiprocessing import Pipe, Process
+from multiprocessing.connection import Connection, wait
+from typing import Callable, Iterable, Iterator, List
+
+from ocrmypdf import Executor, hookimpl
+from ocrmypdf._concurrent import NullProgressBar
+from ocrmypdf.exceptions import InputFileError
+from ocrmypdf.helpers import remove_all_log_handlers
+
+
+class MessageType(Enum):
+    exception = auto()
+    result = auto()
+    complete = auto()
+
+
+def split_every(n: int, iterable: Iterable) -> Iterator:
+    """Split iterable into groups of n.
+
+    >>> list(split_every(4, range(10)))
+    [[0, 1, 2], [3, 4, 5], [6, 7, 8], [9]]
+
+    https://stackoverflow.com/a/22919323
+    """
+    iterator = iter(iterable)
+    return takewhile(bool, (list(islice(iterator, n)) for _ in repeat(None)))
+
+
+def process_sigbus(*args):
+    raise InputFileError("A worker process lost access to an input file")
+
+
+class ConnectionLogHandler(logging.handlers.QueueHandler):
+    def __init__(self, conn: Connection) -> None:
+        # sets the parent's queue to None - parent only touches queue
+        # in enqueue() which we override
+        super().__init__(None)  # type: ignore
+        self.conn = conn
+
+    def enqueue(self, record):
+        self.conn.send(('log', record))
+
+
+def process_loop(
+    conn: Connection, user_init: Callable[[], None], loglevel, task, task_args
+):
+    """Initialize a process pool worker"""
+
+    # Install SIGBUS handler (so our parent process can abort somewhat gracefully)
+    with suppress(AttributeError):  # Windows and Cygwin do not have SIGBUS
+        # Windows and Cygwin do not have pthread_sigmask or SIGBUS
+        signal.signal(signal.SIGBUS, process_sigbus)
+
+    # Reconfigure the root logger for this process to send all messages to a queue
+    h = ConnectionLogHandler(conn)
+    root = logging.getLogger()
+    remove_all_log_handlers(root)
+    root.setLevel(loglevel)
+    root.addHandler(h)
+
+    user_init()
+
+    for args in task_args:
+        try:
+            result = task(args)
+        except Exception as e:
+            conn.send((MessageType.exception, e))
+            break
+        else:
+            conn.send((MessageType.result, result))
+
+    conn.send((MessageType.complete, None))
+    conn.close()
+    return
+
+
+class LambdaExecutor(Executor):
+    def _execute(
+        self,
+        *,
+        use_threads: bool,
+        max_workers: int,
+        tqdm_kwargs: dict,
+        worker_initializer: Callable,
+        task: Callable,
+        task_arguments: Iterable,
+        task_finished: Callable,
+    ):
+        if use_threads and max_workers == 1:
+            with self.pbar_class(**tqdm_kwargs) as pbar:
+                for args in task_arguments:
+                    result = task(args)
+                    task_finished(result, pbar)
+            return
+
+        task_arguments = list(task_arguments)
+        grouped_args = list(
+            zip_longest(*list(split_every(max_workers, task_arguments)))
+        )
+        if not grouped_args:
+            return
+
+        processes: List[Process] = []
+        connections: List[Connection] = []
+        for chunk in grouped_args:
+            parent_conn, child_conn = Pipe()
+
+            worker_args = [args for args in chunk if args is not None]
+            process = Process(
+                target=process_loop,
+                args=(
+                    child_conn,
+                    worker_initializer,
+                    logging.getLogger("").level,
+                    task,
+                    worker_args,
+                ),
+            )
+            process.daemon = True
+            processes.append(process)
+            connections.append(parent_conn)
+
+        for process in processes:
+            process.start()
+
+        with self.pbar_class(**tqdm_kwargs) as pbar:
+            while connections:
+                for r in wait(connections):
+                    if not isinstance(r, Connection):
+                        raise NotImplementedError("We only support Connection()")
+                    try:
+                        msg_type, msg = r.recv()
+                    except EOFError:
+                        connections.remove(r)
+                        continue
+
+                    if msg_type == MessageType.result:
+                        if task_finished:
+                            task_finished(msg, pbar)
+                    elif msg_type == 'log':
+                        record = msg
+                        logger = logging.getLogger(record.name)
+                        logger.handle(record)
+                    elif msg_type == MessageType.complete:
+                        connections.remove(r)
+                    elif msg_type == MessageType.exception:
+                        for process in processes:
+                            process.terminate()
+                        raise msg
+
+        for process in processes:
+            process.join()
+
+
+@hookimpl
+def get_executor(progressbar_class):
+    return LambdaExecutor(pbar_class=progressbar_class)
+
+
+@hookimpl
+def get_logging_console():
+    return logging.StreamHandler()
+
+
+@hookimpl
+def get_progressbar_class():
+    return NullProgressBar

src/ocrmypdf/helpers.py

@@ -0,0 +1,275 @@
+# © 2016 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import logging
+import multiprocessing
+import os
+import shutil
+import warnings
+from collections import namedtuple
+from collections.abc import Iterable
+from contextlib import suppress
+from functools import wraps
+from io import StringIO
+from math import isclose, isfinite
+from pathlib import Path
+from typing import Any, Sequence
+
+import pikepdf
+
+log = logging.getLogger(__name__)
+
+
+class Resolution(namedtuple('Resolution', ('x', 'y'))):
+    """The number of pixels per inch in each 2D direction.
+
+    Resolution objects are considered "equal" for == purposes if they are
+    equal to a reasonable tolerance.
+    """
+
+    __slots__ = ()
+
+    # rel_tol after converting from dpi to pixels per meter and saving
+    # as integer with rounding, as many file formats
+    CONVERSION_ERROR = 0.002
+
+    def round(self, ndigits: int):
+        return Resolution(round(self.x, ndigits), round(self.y, ndigits))
+
+    def to_int(self):
+        return Resolution(int(round(self.x)), int(round(self.y)))
+
+    @classmethod
+    def _isclose(cls, a, b):
+        return isclose(a, b, rel_tol=cls.CONVERSION_ERROR)
+
+    @property
+    def is_square(self) -> bool:
+        return self._isclose(self.x, self.y)
+
+    @property
+    def is_finite(self) -> bool:
+        return isfinite(self.x) and isfinite(self.y)
+
+    def take_max(self, vals, yvals=None):
+        if yvals is not None:
+            return Resolution(max(self.x, *vals), max(self.y, *yvals))
+        max_x, max_y = self.x, self.y
+        for x, y in vals:
+            max_x = max(x, max_x)
+            max_y = max(y, max_y)
+        return Resolution(max_x, max_y)
+
+    def flip_axis(self):
+        return Resolution(self.y, self.x)
+
+    def __str__(self):
+        return f"{self.x:f}x{self.y:f}"
+
+    def __repr__(self):  # pragma: no cover
+        return f"Resolution({self.x}x{self.y} dpi)"
+
+    def __eq__(self, other):
+        if isinstance(other, tuple) and len(other) == 2:
+            other = Resolution(*other)
+        if not isinstance(other, Resolution):
+            return NotImplemented
+        return self._isclose(self.x, other.x) and self._isclose(self.y, other.y)
+
+
+class NeverRaise(Exception):
+    """An exception that is never raised"""
+
+
+def safe_symlink(input_file: os.PathLike, soft_link_name: os.PathLike):
+    """Create a symbolic link at ``soft_link_name``, which references ``input_file``.
+
+    Think of this as copying ``input_file`` to ``soft_link_name`` with less overhead.
+
+    Use symlinks safely. Self-linking loops are prevented. On Windows, file copy is
+    used since symlinks may require administrator privileges. An existing link at the
+    destination is removed.
+    """
+    input_file = os.fspath(input_file)
+    soft_link_name = os.fspath(soft_link_name)
+
+    # Guard against soft linking to oneself
+    if input_file == soft_link_name:
+        log.warning(
+            "No symbolic link created. You are using  the original data directory "
+            "as the working directory."
+        )
+        return
+
+    # Soft link already exists: delete for relink?
+    if os.path.lexists(soft_link_name):
+        # do not delete or overwrite real (non-soft link) file
+        if not os.path.islink(soft_link_name):
+            raise FileExistsError(f"{soft_link_name} exists and is not a link")
+        os.unlink(soft_link_name)
+
+    if not os.path.exists(input_file):
+        raise FileNotFoundError(f"trying to create a broken symlink to {input_file}")
+
+    if os.name == 'nt':
+        # Don't actually use symlinks on Windows due to permission issues
+        shutil.copyfile(input_file, soft_link_name)
+        return
+
+    log.debug("os.symlink(%s, %s)", input_file, soft_link_name)
+
+    # Create symbolic link using absolute path
+    os.symlink(os.path.abspath(input_file), soft_link_name)
+
+
+def samefile(f1: os.PathLike, f2: os.PathLike):
+    if os.name == 'nt':
+        return f1 == f2
+    else:
+        return os.path.samefile(f1, f2)
+
+
+def is_iterable_notstr(thing: Any) -> bool:
+    """Is this is an iterable type, other than a string?"""
+    return isinstance(thing, Iterable) and not isinstance(thing, str)
+
+
+def monotonic(L: Sequence) -> bool:
+    """Does this sequence increase monotonically?"""
+    return all(b > a for a, b in zip(L, L[1:]))
+
+
+def page_number(input_file: os.PathLike) -> int:
+    """Get one-based page number implied by filename (000002.pdf -> 2)"""
+    return int(os.path.basename(os.fspath(input_file))[0:6])
+
+
+def available_cpu_count() -> int:
+    """Returns number of CPUs in the system."""
+    try:
+        return multiprocessing.cpu_count()
+    except NotImplementedError:
+        pass
+    warnings.warn(
+        "Could not get CPU count.  Assuming one (1) CPU." "Use -j N to set manually."
+    )
+    return 1
+
+
+def is_file_writable(test_file: os.PathLike) -> bool:
+    """Intentionally racy test if target is writable.
+
+    We intend to write to the output file if and only if we succeed and
+    can replace it atomically. Before doing the OCR work, make sure
+    the location is writable.
+    """
+    try:
+        p = Path(test_file)
+        if p.is_symlink():
+            p = p.resolve(strict=False)
+
+        # p.is_file() throws an exception in some cases
+        if p.exists() and p.is_file():
+            return os.access(
+                os.fspath(p),
+                os.W_OK,
+                effective_ids=(os.access in os.supports_effective_ids),
+            )
+        else:
+            try:
+                fp = p.open('wb')
+            except OSError:
+                return False
+            else:
+                fp.close()
+                with suppress(OSError):
+                    p.unlink()
+            return True
+    except (OSError, RuntimeError) as e:
+        log.debug(e)
+        log.error(str(e))
+        return False
+
+
+def check_pdf(input_file: Path) -> bool:
+    """Check if a PDF complies with the PDF specification.
+
+    Checks for proper formatting and proper linearization. Uses pikepdf (which in
+    turn, uses QPDF) to perform the checks.
+    """
+    try:
+        pdf = pikepdf.open(input_file)
+    except pikepdf.PdfError as e:
+        log.error(e)
+        return False
+    else:
+        with pdf:
+            messages = pdf.check()
+            for msg in messages:
+                if 'error' in msg.lower():
+                    log.error(msg)
+                else:
+                    log.warning(msg)
+
+            sio = StringIO()
+            linearize_msgs = ''
+            try:
+                # If linearization is missing entirely, we do not complain. We do
+                # complain if linearization is present but incorrect.
+                pdf.check_linearization(sio)
+            except (RuntimeError, pikepdf.ForeignObjectError):
+                pass
+            else:
+                linearize_msgs = sio.getvalue()
+                if linearize_msgs:
+                    log.warning(linearize_msgs)
+
+            if not messages and not linearize_msgs:
+                return True
+            return False
+
+
+def clamp(n, smallest, largest):  # mypy doesn't understand types for this
+    """Clamps the value of ``n`` to between ``smallest`` and ``largest``."""
+    return max(smallest, min(n, largest))
+
+
+def remove_all_log_handlers(logger):
+    "Remove all log handlers, usually used in a child process."
+    for handler in logger.handlers[:]:
+        logger.removeHandler(handler)
+        handler.close()  # To ensure handlers with opened resources are released
+
+
+def pikepdf_enable_mmap():
+    # try:
+    #     if pikepdf._qpdf.set_access_default_mmap(True):
+    #         log.debug("pikepdf mmap enabled")
+    # except AttributeError:
+    #     log.debug("pikepdf mmap not available")
+    # We found a race condition probably related to pybind issue #2252 that can
+    # cause a crash. For now, disable pikepdf mmap to be on the safe side.
+    # Fix is not in pybind11 2.6.0
+    # log.debug("pikepdf mmap disabled")
+    return
+
+
+def deprecated(func):
+    """Warn that function is deprecated."""
+
+    @wraps(func)
+    def new_func(*args, **kwargs):
+        warnings.simplefilter('always', DeprecationWarning)  # turn off filter
+        warnings.warn(
+            f"Call to deprecated function {func.__name__}.",
+            category=DeprecationWarning,
+            stacklevel=2,
+        )
+        warnings.simplefilter('default', DeprecationWarning)  # reset filter
+        return func(*args, **kwargs)
+
+    return new_func

src/ocrmypdf/hocrtransform.py

@@ -0,0 +1,496 @@
+#!/usr/bin/env python3
+#
+# Copyright (c) 2010, Jonathan Brinley
+#   Original version from: https://github.com/jbrinley/HocrConverter
+#
+# Copyright (c) 2013-14, Julien Pfefferkorn
+#   Modifications
+#
+# Copyright (c) 2015-16, James R. Barlow
+#   Set text to transparent
+#
+# Permission is hereby granted, free of charge, to any person obtaining a
+# copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be included
+# in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+import argparse
+import os
+import re
+from math import atan, cos, sin
+from pathlib import Path
+from typing import Any, NamedTuple, Optional, Tuple, Union
+from xml.etree import ElementTree
+
+from reportlab.lib.colors import black, cyan, magenta, red
+from reportlab.lib.units import inch
+from reportlab.pdfgen.canvas import Canvas
+
+# According to Wikipedia these languages are supported in the ISO-8859-1 character
+# set, meaning reportlab can generate them and they are compatible with hocr,
+# assuming Tesseract has the necessary languages installed. Note that there may
+# not be language packs for them.
+HOCR_OK_LANGS = frozenset(
+    [
+        # Languages fully covered by Latin-1:
+        'afr',  # Afrikaans
+        'alb',  # Albanian
+        'ast',  # Leonese
+        'baq',  # Basque
+        'bre',  # Breton
+        'cos',  # Corsican
+        'eng',  # English
+        'eus',  # Basque
+        'fao',  # Faoese
+        'gla',  # Scottish Gaelic
+        'glg',  # Galician
+        'glv',  # Manx
+        'ice',  # Icelandic
+        'ind',  # Indonesian
+        'isl',  # Icelandic
+        'ita',  # Italian
+        'ltz',  # Luxembourgish
+        'mal',  # Malay Rumi
+        'mga',  # Irish
+        'nor',  # Norwegian
+        'oci',  # Occitan
+        'por',  # Portugeuse
+        'roh',  # Romansh
+        'sco',  # Scots
+        'sma',  # Sami
+        'spa',  # Spanish
+        'sqi',  # Albanian
+        'swa',  # Swahili
+        'swe',  # Swedish
+        'tgl',  # Tagalog
+        'wln',  # Walloon
+        # Languages supported by Latin-1 except for a few rare characters that OCR
+        # is probably not trained to recognize anyway:
+        'cat',  # Catalan
+        'cym',  # Welsh
+        'dan',  # Danish
+        'deu',  # German
+        'dut',  # Dutch
+        'est',  # Estonian
+        'fin',  # Finnish
+        'fra',  # French
+        'hun',  # Hungarian
+        'kur',  # Kurdish
+        'nld',  # Dutch
+        'wel',  # Welsh
+    ]
+)
+
+
+Element = ElementTree.Element
+
+
+class Rect(NamedTuple):  # pylint: disable=inherit-non-class
+    """A rectangle for managing PDF coordinates."""
+
+    x1: Any
+    y1: Any
+    x2: Any
+    y2: Any
+
+
+class HocrTransformError(Exception):
+    pass
+
+
+class HocrTransform:
+
+    """
+    A class for converting documents from the hOCR format.
+    For details of the hOCR format, see:
+    http://kba.cloud/hocr-spec/
+    """
+
+    box_pattern = re.compile(r'bbox((\s+\d+){4})')
+    baseline_pattern = re.compile(
+        r'''
+        baseline \s+
+        ([\-\+]?\d*\.?\d*) \s+  # +/- decimal float
+        ([\-\+]?\d+)            # +/- int''',
+        re.VERBOSE,
+    )
+    ligatures = str.maketrans(
+        {'ff': 'ff', 'ffi': 'f‌f‌i', 'ffl': 'f‌f‌l', 'fi': 'fi', 'fl': 'fl'}
+    )
+
+    def __init__(self, *, hocr_filename: Union[str, Path], dpi: float):
+        self.dpi = dpi
+        self.hocr = ElementTree.parse(os.fspath(hocr_filename))
+
+        # if the hOCR file has a namespace, ElementTree requires its use to
+        # find elements
+        matches = re.match(r'({.*})html', self.hocr.getroot().tag)
+        self.xmlns = ''
+        if matches:
+            self.xmlns = matches.group(1)
+
+        # get dimension in pt (not pixel!!!!) of the OCRed image
+        self.width, self.height = None, None
+        for div in self.hocr.findall(self._child_xpath('div', 'ocr_page')):
+            coords = self.element_coordinates(div)
+            pt_coords = self.pt_from_pixel(coords)
+            self.width = pt_coords.x2 - pt_coords.x1
+            self.height = pt_coords.y2 - pt_coords.y1
+            # there shouldn't be more than one, and if there is, we don't want
+            # it
+            break
+        if self.width is None or self.height is None:
+            raise HocrTransformError("hocr file is missing page dimensions")
+
+    def __str__(self):  # pragma: no cover
+        """
+        Return the textual content of the HTML body
+        """
+        if self.hocr is None:
+            return ''
+        body = self.hocr.find(self._child_xpath('body'))
+        if body:
+            return self._get_element_text(body)
+        else:
+            return ''
+
+    def _get_element_text(self, element: Element):
+        """
+        Return the textual content of the element and its children
+        """
+        text = ''
+        if element.text is not None:
+            text += element.text
+        for child in element:
+            text += self._get_element_text(child)
+        if element.tail is not None:
+            text += element.tail
+        return text
+
+    @classmethod
+    def element_coordinates(cls, element: Element) -> Rect:
+        """
+        Returns a tuple containing the coordinates of the bounding box around
+        an element
+        """
+        out = Rect._make(0 for _ in range(4))
+        if 'title' in element.attrib:
+            matches = cls.box_pattern.search(element.attrib['title'])
+            if matches:
+                coords = matches.group(1).split()
+                out = Rect._make(int(coords[n]) for n in range(4))
+        return out
+
+    @classmethod
+    def baseline(cls, element: Element) -> Tuple[float, float]:
+        """
+        Returns a tuple containing the baseline slope and intercept.
+        """
+        if 'title' in element.attrib:
+            matches = cls.baseline_pattern.search(element.attrib['title'])
+            if matches:
+                return float(matches.group(1)), int(matches.group(2))
+        return (0.0, 0.0)
+
+    def pt_from_pixel(self, pxl) -> Rect:
+        """
+        Returns the quantity in PDF units (pt) given quantity in pixels
+        """
+        return Rect._make((c / self.dpi * inch) for c in pxl)
+
+    def _child_xpath(self, html_tag: str, html_class: Optional[str] = None) -> str:
+        xpath = f".//{self.xmlns}{html_tag}"
+        if html_class:
+            xpath += f"[@class='{html_class}']"
+        return xpath
+
+    @classmethod
+    def replace_unsupported_chars(cls, s: str) -> str:
+        """
+        Given an input string, returns the corresponding string that:
+        * is available in the Helvetica facetype
+        * does not contain any ligature (to allow easy search in the PDF file)
+        """
+        return s.translate(cls.ligatures)
+
+    def topdown_position(self, element):
+        pxl_line_coords = self.element_coordinates(element)
+        line_box = self.pt_from_pixel(pxl_line_coords)
+        # Coordinates here are still in the hocr coordinate system, so 0 on the y axis
+        # is the top of the page and increasing values of y will move towards the
+        # bottom of the page.
+        return line_box.y2
+
+    def to_pdf(
+        self,
+        *,
+        out_filename: Path,
+        image_filename: Optional[Path] = None,
+        show_bounding_boxes: bool = False,
+        fontname: str = "Helvetica",
+        invisible_text: bool = False,
+        interword_spaces: bool = False,
+    ) -> None:
+        """
+        Creates a PDF file with an image superimposed on top of the text.
+        Text is positioned according to the bounding box of the lines in
+        the hOCR file.
+        The image need not be identical to the image used to create the hOCR
+        file.
+        It can have a lower resolution, different color mode, etc.
+
+        Arguments:
+            out_filename: Path of PDF to write.
+            image_filename: Image to use for this file. If omitted, the OCR text
+                is shown.
+            show_bounding_boxes: Show bounding boxes around various text regions,
+                for debugging.
+            fontname: Name of font to use.
+            invisible_text: If True, text is rendered invisible so that is
+                selectable but never drawn. If False, text is visible and may
+                be seen if the image is skipped or deleted in Acrobat.
+            interword_spaces: If True, insert spaces between words rather than
+                drawing each word without spaces. Generally this improves text
+                extraction.
+        """
+        # create the PDF file
+        # page size in points (1/72 in.)
+        pdf = Canvas(
+            os.fspath(out_filename),
+            pagesize=(self.width, self.height),
+            pageCompression=1,
+        )
+
+        # draw bounding box for each paragraph
+        # light blue for bounding box of paragraph
+        pdf.setStrokeColor(cyan)
+        # light blue for bounding box of paragraph
+        pdf.setFillColor(cyan)
+        pdf.setLineWidth(0)  # no line for bounding box
+        for elem in self.hocr.iterfind(self._child_xpath('p', 'ocr_par')):
+            elemtxt = self._get_element_text(elem).rstrip()
+            if len(elemtxt) == 0:
+                continue
+
+            pxl_coords = self.element_coordinates(elem)
+            pt = self.pt_from_pixel(pxl_coords)
+
+            # draw the bbox border
+            if show_bounding_boxes:  # pragma: no cover
+                pdf.rect(
+                    pt.x1, self.height - pt.y2, pt.x2 - pt.x1, pt.y2 - pt.y1, fill=1
+                )
+
+        found_lines = False
+        for line in (
+            element
+            for element in self.hocr.iterfind(self._child_xpath('span'))
+            if 'class' in element.attrib
+            and element.attrib['class'] in {'ocr_header', 'ocr_line', 'ocr_textfloat'}
+        ):
+            found_lines = True
+            self._do_line(
+                pdf,
+                line,
+                "ocrx_word",
+                fontname,
+                invisible_text,
+                interword_spaces,
+                show_bounding_boxes,
+            )
+
+        if not found_lines:
+            # Tesseract did not report any lines (just words)
+            root = self.hocr.find(self._child_xpath('div', 'ocr_page'))
+            self._do_line(
+                pdf,
+                root,
+                "ocrx_word",
+                fontname,
+                invisible_text,
+                interword_spaces,
+                show_bounding_boxes,
+            )
+        # put the image on the page, scaled to fill the page
+        if image_filename is not None:
+            pdf.drawImage(
+                os.fspath(image_filename), 0, 0, width=self.width, height=self.height
+            )
+
+        # finish up the page and save it
+        pdf.showPage()
+        pdf.save()
+
+    @classmethod
+    def polyval(cls, poly, x):  # pragma: no cover
+        return x * poly[0] + poly[1]
+
+    def _do_line(
+        self,
+        pdf: Canvas,
+        line: Optional[Element],
+        elemclass: str,
+        fontname: str,
+        invisible_text: bool,
+        interword_spaces: bool,
+        show_bounding_boxes: bool,
+    ):
+        if line is None:
+            return
+        pxl_line_coords = self.element_coordinates(line)
+        line_box = self.pt_from_pixel(pxl_line_coords)
+        line_height = line_box.y2 - line_box.y1
+
+        slope, pxl_intercept = self.baseline(line)
+        if abs(slope) < 0.005:
+            slope = 0.0
+        angle = atan(slope)
+        cos_a, sin_a = cos(angle), sin(angle)
+
+        text = pdf.beginText()
+        intercept = pxl_intercept / self.dpi * inch
+
+        # Don't allow the font to break out of the bounding box. Division by
+        # cos_a accounts for extra clearance between the glyph's vertical axis
+        # on a sloped baseline and the edge of the bounding box.
+        fontsize = (line_height - abs(intercept)) / cos_a
+        text.setFont(fontname, fontsize)
+        if invisible_text:
+            text.setTextRenderMode(3)  # Invisible (indicates OCR text)
+
+        # Intercept is normally negative, so this places it above the bottom
+        # of the line box
+        baseline_y2 = self.height - (line_box.y2 + intercept)
+
+        if show_bounding_boxes:  # pragma: no cover
+            # draw the baseline in magenta, dashed
+            pdf.setDash()
+            pdf.setStrokeColor(magenta)
+            pdf.setLineWidth(0.5)
+            # negate slope because it is defined as a rise/run in pixel
+            # coordinates and page coordinates have the y axis flipped
+            pdf.line(
+                line_box.x1,
+                baseline_y2,
+                line_box.x2,
+                self.polyval((-slope, baseline_y2), line_box.x2 - line_box.x1),
+            )
+            # light green for bounding box of word/line
+            pdf.setDash(6, 3)
+            pdf.setStrokeColor(red)
+
+        text.setTextTransform(cos_a, -sin_a, sin_a, cos_a, line_box.x1, baseline_y2)
+        pdf.setFillColor(black)  # text in black
+
+        elements = line.findall(self._child_xpath('span', elemclass))
+        for elem in elements:
+            elemtxt = self._get_element_text(elem).strip()
+            elemtxt = self.replace_unsupported_chars(elemtxt)
+            if elemtxt == '':
+                continue
+
+            pxl_coords = self.element_coordinates(elem)
+            box = self.pt_from_pixel(pxl_coords)
+            if interword_spaces:
+                # if  `--interword-spaces` is true, append a space
+                # to the end of each text element to allow simpler PDF viewers
+                # such as PDF.js to better recognize words in search and copy
+                # and paste. Do not remove space from last word in line, even
+                # though it would look better, because it will interfere with
+                # naive text extraction. \n does not work either.
+                elemtxt += ' '
+                box = Rect._make(
+                    (
+                        box.x1,
+                        line_box.y1,
+                        box.x2 + pdf.stringWidth(' ', fontname, line_height),
+                        line_box.y2,
+                    )
+                )
+            box_width = box.x2 - box.x1
+            font_width = pdf.stringWidth(elemtxt, fontname, fontsize)
+
+            # draw the bbox border
+            if show_bounding_boxes:  # pragma: no cover
+                pdf.rect(
+                    box.x1, self.height - line_box.y2, box_width, line_height, fill=0
+                )
+
+            # Adjust relative position of cursor
+            # This is equivalent to:
+            #   text.setTextOrigin(pt.x1, self.height - line_box.y2)
+            # but the former generates a full text reposition matrix (Tm) in the
+            # content stream while this issues a "offset" (Td) command.
+            # .moveCursor() is relative to start of the text line, where the
+            # "text line" means whatever reportlab defines it as. Do not use
+            # use .getCursor(), since moveCursor() rather unintuitively plans
+            # its moves relative to .getStartOfLine().
+            # For skewed lines, in the text transform we set up a rotated
+            # coordinate system, so we don't have to account for the
+            # incremental offset. Surprisingly most PDF viewers can handle this.
+            cursor = text.getStartOfLine()
+            dx = box.x1 - cursor[0]
+            dy = baseline_y2 - cursor[1]
+            text.moveCursor(dx, dy)
+
+            # If reportlab tells us this word is 0 units wide, our best seems
+            # to be to suppress this text
+            if font_width > 0:
+                text.setHorizScale(100 * box_width / font_width)
+                text.textOut(elemtxt)
+        pdf.drawText(text)
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description='Convert hocr file to PDF')
+    parser.add_argument(
+        '-b',
+        '--boundingboxes',
+        action="store_true",
+        default=False,
+        help='Show bounding boxes borders',
+    )
+    parser.add_argument(
+        '-r',
+        '--resolution',
+        type=int,
+        default=300,
+        help='Resolution of the image that was OCRed',
+    )
+    parser.add_argument(
+        '-i',
+        '--image',
+        default=None,
+        help='Path to the image to be placed above the text',
+    )
+    parser.add_argument(
+        '--interword-spaces',
+        action='store_true',
+        default=False,
+        help='Add spaces between words',
+    )
+    parser.add_argument('hocrfile', help='Path to the hocr file to be parsed')
+    parser.add_argument('outputfile', help='Path to the PDF file to be generated')
+    args = parser.parse_args()
+
+    hocr = HocrTransform(hocr_filename=args.hocrfile, dpi=args.resolution)
+    hocr.to_pdf(
+        out_filename=args.outputfile,
+        image_filename=args.image,
+        show_bounding_boxes=args.boundingboxes,
+        interword_spaces=args.interword_spaces,
+    )

src/ocrmypdf/optimize.py

@@ -0,0 +1,646 @@
+# © 2018 James R. Barlow: github.com/jbarlow83
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+
+import logging
+import sys
+import tempfile
+from collections import defaultdict
+from os import fspath
+from pathlib import Path
+from typing import (
+    Callable,
+    Dict,
+    Iterator,
+    List,
+    MutableSet,
+    NamedTuple,
+    NewType,
+    Optional,
+    Sequence,
+    Tuple,
+)
+
+import img2pdf
+from pikepdf import (
+    Dictionary,
+    Name,
+    Object,
+    ObjectStreamMode,
+    Pdf,
+    PdfImage,
+    Stream,
+    UnsupportedImageTypeError,
+)
+from PIL import Image
+
+from ocrmypdf._concurrent import Executor, SerialExecutor
+from ocrmypdf._exec import jbig2enc, pngquant
+from ocrmypdf._jobcontext import PdfContext
+from ocrmypdf.exceptions import OutputFileAccessError
+from ocrmypdf.helpers import safe_symlink
+
+log = logging.getLogger(__name__)
+
+DEFAULT_JPEG_QUALITY = 75
+DEFAULT_PNG_QUALITY = 70
+
+
+Xref = NewType('Xref', int)
+
+
+class XrefExt(NamedTuple):  # pylint: disable=inherit-non-class
+    xref: Xref
+    ext: str
+
+
+def img_name(root: Path, xref: Xref, ext: str) -> Path:
+    return root / f'{xref:08d}{ext}'
+
+
+def png_name(root: Path, xref: Xref) -> Path:
+    return img_name(root, xref, '.png')
+
+
+def jpg_name(root: Path, xref: Xref) -> Path:
+    return img_name(root, xref, '.jpg')
+
+
+def extract_image_filter(
+    pike: Pdf, root: Path, image: Stream, xref: Xref
+) -> Optional[Tuple[PdfImage, Tuple[Name, Object]]]:
+    del pike  # unused args
+    del root
+
+    if image.Subtype != Name.Image:
+        return None
+    if image.Length < 100:
+        log.debug(f"Skipping small image, xref {xref}")
+        return None
+    if image.Width < 8 or image.Height < 8:  # Issue 732
+        log.debug(f"Skipping oddly sized image, xref {xref}")
+        return None
+
+    pim = PdfImage(image)
+
+    if len(pim.filter_decodeparms) > 1:
+        log.debug(f"Skipping multiply filtered image, xref {xref}")
+        return None
+    filtdp = pim.filter_decodeparms[0]
+
+    if pim.bits_per_component > 8:
+        log.debug(f"Skipping wide gamut image, xref {xref}")
+        return None  # Don't mess with wide gamut images
+
+    if filtdp[0] == Name.JPXDecode:
+        log.debug(f"Skipping JPEG2000 image, xref {xref}")
+        return None  # Don't do JPEG2000
+
+    if filtdp[0] == Name.CCITTFaxDecode and filtdp[1].get('/K', 0) >= 0:
+        log.debug(f"Skipping CCITT Group 3 image, xref {xref}")
+        return None  # pikepdf doesn't support Group 3 yet
+
+    if Name.Decode in image:
+        log.debug(f"Skipping image with Decode table, xref {xref}")
+        return None  # Don't mess with custom Decode tables
+
+    return pim, filtdp
+
+
+def extract_image_jbig2(
+    *, pike: Pdf, root: Path, image: Stream, xref: Xref, options
+) -> Optional[XrefExt]:
+    del options  # unused arg
+
+    result = extract_image_filter(pike, root, image, xref)
+    if result is None:
+        return None
+    pim, filtdp = result
+
+    if (
+        pim.bits_per_component == 1
+        and filtdp[0] != Name.JBIG2Decode
+        and jbig2enc.available()
+    ):
+        # Save any colorspace associated with the image, so that we
+        # will export a pure 1-bit PNG with no palette or ICC profile.
+        # Showing the palette or ICC to jbig2enc will cause it to perform
+        # colorspace transform to 1bpp, which will conflict the palette or
+        # ICC if it exists.
+        colorspace = pim.obj.get(Name.ColorSpace, None)
+        if colorspace is not None or pim.image_mask:
+            try:
+                # Set to DeviceGray temporarily; we already in 1 bpc.
+                pim.obj.ColorSpace = Name.DeviceGray
+                imgname = root / f'{xref:08d}'
+                with imgname.open('wb') as f:
+                    ext = pim.extract_to(stream=f)
+                imgname.rename(imgname.with_suffix(ext))
+            except UnsupportedImageTypeError:
+                return None
+            finally:
+                # Restore image colorspace after temporarily setting it to DeviceGray
+                if colorspace is not None:
+                    pim.obj.ColorSpace = colorspace
+                else:
+                    del pim.obj.ColorSpace
+            return XrefExt(xref, ext)
+    return None
+
+
+def extract_image_generic(
+    *, pike: Pdf, root: Path, image: Stream, xref: Xref, options
+) -> Optional[XrefExt]:
+    result = extract_image_filter(pike, root, image, xref)
+    if result is None:
+        return None
+    pim, filtdp = result
+
+    # Don't try to PNG-optimize 1bpp images, since JBIG2 does it better.
+    if pim.bits_per_component == 1:
+        return None
+
+    if filtdp[0] == Name.DCTDecode and options.optimize >= 2:
+        # This is a simple heuristic derived from some training data, that has
+        # about a 70% chance of guessing whether the JPEG is high quality,
+        # and possibly recompressible, or not. The number itself doesn't mean
+        # anything.
+        # bytes_per_pixel = int(raw_jpeg.Length) / (w * h)
+        # jpeg_quality_estimate = 117.0 * (bytes_per_pixel ** 0.213)
+        # if jpeg_quality_estimate < 65:
+        #     return None
+
+        # We could get the ICC profile here, but there's no need to look at it
+        # for quality transcoding
+        # if icc:
+        #     stream = BytesIO(raw_jpeg.read_raw_bytes())
+        #     iccbytes = icc.read_bytes()
+        #     with Image.open(stream) as im:
+        #         im.save(jpg_name(root, xref), icc_profile=iccbytes)
+        try:
+            imgname = root / f'{xref:08d}'
+            with imgname.open('wb') as f:
+                ext = pim.extract_to(stream=f)
+            imgname.rename(imgname.with_suffix(ext))
+        except UnsupportedImageTypeError:
+            return None
+        return XrefExt(xref, ext)
+    elif (
+        pim.indexed
+        and pim.colorspace in pim.SIMPLE_COLORSPACES
+        and options.optimize >= 3
+    ):
+        # Try to improve on indexed images - these are far from low hanging
+        # fruit in most cases
+        pim.as_pil_image().save(png_name(root, xref))
+        return XrefExt(xref, '.png')
+    elif not pim.indexed and pim.colorspace in pim.SIMPLE_COLORSPACES:
+        # An optimization opportunity here, not currently taken, is directly
+        # generating a PNG from compressed data
+        pim.as_pil_image().save(png_name(root, xref))
+        return XrefExt(xref, '.png')
+    elif (
+        not pim.indexed
+        and pim.colorspace == Name.ICCBased
+        and pim.bits_per_component == 1
+        and not options.jbig2_lossy
+    ):
+        # We can losslessly optimize 1-bit images to CCITT or JBIG2 without
+        # paying any attention to the ICC profile, provided we're not doing
+        # lossy JBIG2
+        pim.as_pil_image().save(png_name(root, xref))
+        return XrefExt(xref, '.png')
+
+    return None
+
+
+def extract_images(
+    pike: Pdf,
+    root: Path,
+    options,
+    extract_fn: Callable[..., Optional[XrefExt]],
+) -> Iterator[Tuple[int, XrefExt]]:
+    """Extract image using extract_fn
+
+    Enumerate images on each page, lookup their xref/ID number in the PDF.
+    Exclude images that are soft masks (i.e. alpha transparency related).
+    Record the page number on which an image is first used, since images may be
+    used on multiple pages (or multiple times on the same page).
+
+    Current we do not check Form XObjects or other objects that may contain
+    images, and we don't evaluate alternate images or thumbnails.
+
+    extract_fn must decide if wants to extract the image in this context. If
+    it does a tuple should be returned: (xref, ext) where .ext is the file
+    extension. extract_fn must also extract the file it finds interesting.
+    """
+
+    include_xrefs: MutableSet[Xref] = set()
+    exclude_xrefs: MutableSet[Xref] = set()
+    pageno_for_xref = {}
+    errors = 0
+    for pageno, page in enumerate(pike.pages):
+        try:
+            xobjs = page.Resources.XObject
+        except AttributeError:
+            continue
+        for _imname, image in dict(xobjs).items():
+            if image.objgen[1] != 0:
+                continue  # Ignore images in an incremental PDF
+            xref = Xref(image.objgen[0])
+            if hasattr(image, 'SMask'):
+                # Ignore soft masks
+                smask_xref = Xref(image.SMask.objgen[0])
+                exclude_xrefs.add(smask_xref)
+                log.debug(f"Skipping image {smask_xref} because it is an SMask")
+            include_xrefs.add(xref)
+            log.debug(f"Treating {xref} as an optimization candidate")
+            if xref not in pageno_for_xref:
+                pageno_for_xref[xref] = pageno
+
+    working_xrefs = include_xrefs - exclude_xrefs
+    for xref in working_xrefs:
+        image = pike.get_object((xref, 0))
+        try:
+            result = extract_fn(
+                pike=pike, root=root, image=image, xref=xref, options=options
+            )
+        except Exception:  # pylint: disable=broad-except
+            log.exception(f"While extracting image xref {xref}, an error occurred")
+            errors += 1
+        else:
+            if result:
+                _, ext = result
+                yield pageno_for_xref[xref], XrefExt(xref, ext)
+
+
+def extract_images_generic(
+    pike: Pdf, root: Path, options
+) -> Tuple[List[Xref], List[Xref]]:
+    """Extract any >=2bpp image we think we can improve"""
+
+    jpegs = []
+    pngs = []
+    for _, xref_ext in extract_images(pike, root, options, extract_image_generic):
+        log.debug('%s', xref_ext)
+        if xref_ext.ext == '.png':
+            pngs.append(xref_ext.xref)
+        elif xref_ext.ext == '.jpg':
+            jpegs.append(xref_ext.xref)
+    log.debug("Optimizable images: JPEGs: %s PNGs: %s", len(jpegs), len(pngs))
+    return jpegs, pngs
+
+
+def extract_images_jbig2(pike: Pdf, root: Path, options) -> Dict[int, List[XrefExt]]:
+    """Extract any bitonal image that we think we can improve as JBIG2"""
+
+    jbig2_groups = defaultdict(list)
+    for pageno, xref_ext in extract_images(pike, root, options, extract_image_jbig2):
+        group = pageno // options.jbig2_page_group_size
+        jbig2_groups[group].append(xref_ext)
+
+    log.debug("Optimizable images: JBIG2 groups: %s", (len(jbig2_groups),))
+    return jbig2_groups
+
+
+def _produce_jbig2_images(
+    jbig2_groups: Dict[int, List[XrefExt]], root: Path, options, executor: Executor
+) -> None:
+    """Produce JBIG2 images from their groups"""
+
+    def jbig2_group_args(root: Path, groups: Dict[int, List[XrefExt]]):
+        for group, xref_exts in groups.items():
+            prefix = f'group{group:08d}'
+            yield (
+                fspath(root),  # =cwd
+                (img_name(root, xref, ext) for xref, ext in xref_exts),  # =infiles
+                prefix,  # =out_prefix
+            )
+
+    def jbig2_single_args(root, groups: Dict[int, List[XrefExt]]):
+        for group, xref_exts in groups.items():
+            prefix = f'group{group:08d}'
+            # Second loop is to ensure multiple images per page are unpacked
+            for n, xref_ext in enumerate(xref_exts):
+                xref, ext = xref_ext
+                yield (
+                    fspath(root),
+                    img_name(root, xref, ext),
+                    root / f'{prefix}.{n:04d}',
+                )
+
+    if options.jbig2_page_group_size > 1:
+        jbig2_args = jbig2_group_args
+        jbig2_convert = jbig2enc.convert_group_mp
+    else:
+        jbig2_args = jbig2_single_args
+        jbig2_convert = jbig2enc.convert_single_mp
+
+    executor(
+        use_threads=True,
+        max_workers=options.jobs,
+        tqdm_kwargs=dict(
+            total=len(jbig2_groups),
+            desc="JBIG2",
+            unit='item',
+            disable=not options.progress_bar,
+        ),
+        task=jbig2_convert,
+        task_arguments=jbig2_args(root, jbig2_groups),
+    )
+
+
+def convert_to_jbig2(
+    pike: Pdf,
+    jbig2_groups: Dict[int, List[XrefExt]],
+    root: Path,
+    options,
+    executor: Executor,
+) -> None:
+    """Convert images to JBIG2 and insert into PDF.
+
+    When the JBIG2 page group size is > 1 we do several JBIG2 images at once
+    and build a symbol dictionary that will span several pages. Each JBIG2
+    image must reference to its symbol dictionary. If too many pages shared the
+    same dictionary JBIG2 encoding becomes more expensive and less efficient.
+    The default value of 10 was determined through testing. Currently this
+    must be lossy encoding since jbig2enc does not support refinement coding.
+
+    When the JBIG2 symbolic coder is not used, each JBIG2 stands on its own
+    and needs no dictionary. Currently this must be lossless JBIG2.
+    """
+    jbig2_globals_dict: Optional[Dictionary]
+
+    _produce_jbig2_images(jbig2_groups, root, options, executor)
+
+    for group, xref_exts in jbig2_groups.items():
+        prefix = f'group{group:08d}'
+        jbig2_symfile = root / (prefix + '.sym')
+        if jbig2_symfile.exists():
+            jbig2_globals_data = jbig2_symfile.read_bytes()
+            jbig2_globals = Stream(pike, jbig2_globals_data)
+            jbig2_globals_dict = Dictionary(JBIG2Globals=jbig2_globals)
+        elif options.jbig2_page_group_size == 1:
+            jbig2_globals_dict = None
+        else:
+            raise FileNotFoundError(jbig2_symfile)
+
+        for n, xref_ext in enumerate(xref_exts):
+            xref, _ = xref_ext
+            jbig2_im_file = root / (prefix + f'.{n:04d}')
+            jbig2_im_data = jbig2_im_file.read_bytes()
+            im_obj = pike.get_object(xref, 0)
+            im_obj.write(
+                jbig2_im_data, filter=Name.JBIG2Decode, decode_parms=jbig2_globals_dict
+            )
+
+
+def _optimize_jpeg(args: Tuple[Xref, Path, Path, int]) -> Tuple[Xref, Optional[Path]]:
+    xref, in_jpg, opt_jpg, jpeg_quality = args
+
+    # This may produce a debug warning from PIL
+    # DEBUG:PIL.Image:Error closing: 'NoneType' object has no attribute
+    # 'close'.  Seems to be mostly harmless
+    # https://github.com/python-pillow/Pillow/issues/1144
+    with Image.open(in_jpg) as im:
+        im.save(opt_jpg, optimize=True, quality=jpeg_quality)
+
+    if opt_jpg.stat().st_size > in_jpg.stat().st_size:
+        log.debug("xref %s, jpeg, made larger - skip", xref)
+        opt_jpg.unlink()
+        opt_jpg = None
+    return xref, opt_jpg
+
+
+def transcode_jpegs(
+    pike: Pdf, jpegs: Sequence[Xref], root: Path, options, executor: Executor
+) -> None:
+    def jpeg_args() -> Iterator[Tuple[Xref, Path, Path, int]]:
+        for xref in jpegs:
+            in_jpg = jpg_name(root, xref)
+            opt_jpg = in_jpg.with_suffix('.opt.jpg')
+            yield xref, in_jpg, opt_jpg, options.jpeg_quality
+
+    def finish_jpeg(result: Tuple[Xref, Optional[Path]], pbar):
+        xref, opt_jpg = result
+        if opt_jpg:
+            compdata = opt_jpg.read_bytes()  # JPEG can inserted into PDF as is
+            im_obj = pike.get_object(xref, 0)
+            im_obj.write(compdata, filter=Name.DCTDecode)
+        pbar.update()
+
+    executor(
+        use_threads=True,  # Processes are significantly slower at this task
+        max_workers=options.jobs,
+        tqdm_kwargs=dict(
+            desc="JPEGs",
+            total=len(jpegs),
+            unit='image',
+            disable=not options.progress_bar,
+        ),
+        task=_optimize_jpeg,
+        task_arguments=jpeg_args(),
+        task_finished=finish_jpeg,
+    )
+
+
+def _transcode_png(pike: Pdf, filename: Path, xref: Xref) -> bool:
+    output = filename.with_suffix('.png.pdf')
+    with output.open('wb') as f:
+        img2pdf.convert(fspath(filename), outputstream=f)
+
+    with Pdf.open(output) as pdf_image:
+        foreign_image = next(iter(pdf_image.pages[0].images.values()))
+        local_image = pike.copy_foreign(foreign_image)
+
+        im_obj = pike.get_object(xref, 0)
+        im_obj.write(
+            local_image.read_raw_bytes(),
+            filter=local_image.Filter,
+            decode_parms=local_image.DecodeParms,
+        )
+
+        # Don't copy keys from the new image...
+        del_keys = set(im_obj.keys()) - set(local_image.keys())
+        # ...except for the keep_fields, which are essential to displaying
+        # the image correctly and preserving its metadata. (/Decode arrays
+        # and /SMaskInData are implicitly discarded prior to this point.)
+        keep_fields = {
+            '/ID',
+            '/Intent',
+            '/Interpolate',
+            '/Mask',
+            '/Metadata',
+            '/OC',
+            '/OPI',
+            '/SMask',
+            '/StructParent',
+        }
+        del_keys -= keep_fields
+        for key in local_image.keys():
+            if key != Name.Length and str(key) not in keep_fields:
+                im_obj[key] = local_image[key]
+        for key in del_keys:
+            del im_obj[key]
+    return True
+
+
+def transcode_pngs(
+    pike: Pdf,
+    images: Sequence[Xref],
+    image_name_fn: Callable[[Path, Xref], Path],
+    root: Path,
+    options,
+    executor,
+) -> None:
+    modified: MutableSet[Xref] = set()
+    if options.optimize >= 2:
+        png_quality = (
+            max(10, options.png_quality - 10),
+            min(100, options.png_quality + 10),
+        )
+
+        def pngquant_args():
+            for xref in images:
+                log.debug(image_name_fn(root, xref))
+                yield (
+                    image_name_fn(root, xref),
+                    png_name(root, xref),
+                    png_quality[0],
+                    png_quality[1],
+                )
+                modified.add(xref)
+
+        executor(
+            use_threads=True,
+            max_workers=options.jobs,
+            tqdm_kwargs=dict(
+                desc="PNGs",
+                total=len(images),
+                unit='image',
+                disable=not options.progress_bar,
+            ),
+            task=pngquant.quantize_mp,
+            task_arguments=pngquant_args(),
+        )
+
+    for xref in modified:
+        filename = png_name(root, xref)
+        _transcode_png(pike, filename, xref)
+
+
+DEFAULT_EXECUTOR = SerialExecutor()
+
+
+def optimize(
+    input_file: Path,
+    output_file: Path,
+    context,
+    save_settings,
+    executor: Executor = DEFAULT_EXECUTOR,
+) -> None:
+    options = context.options
+    if options.optimize == 0:
+        safe_symlink(input_file, output_file)
+        return
+
+    if options.jpeg_quality == 0:
+        options.jpeg_quality = DEFAULT_JPEG_QUALITY if options.optimize < 3 else 40
+    if options.png_quality == 0:
+        options.png_quality = DEFAULT_PNG_QUALITY if options.optimize < 3 else 30
+    if options.jbig2_page_group_size == 0:
+        options.jbig2_page_group_size = 10 if options.jbig2_lossy else 1
+
+    with Pdf.open(input_file) as pike:
+        root = output_file.parent / 'images'
+        root.mkdir(exist_ok=True)
+
+        jpegs, pngs = extract_images_generic(pike, root, options)
+        transcode_jpegs(pike, jpegs, root, options, executor)
+        # if options.optimize >= 2:
+        # Try pngifying the jpegs
+        #    transcode_pngs(pike, jpegs, jpg_name, root, options)
+        transcode_pngs(pike, pngs, png_name, root, options, executor)
+
+        jbig2_groups = extract_images_jbig2(pike, root, options)
+        convert_to_jbig2(pike, jbig2_groups, root, options, executor)
+
+        target_file = output_file.with_suffix('.opt.pdf')
+        pike.remove_unreferenced_resources()
+        pike.save(target_file, **save_settings)
+
+    input_size = input_file.stat().st_size
+    output_size = target_file.stat().st_size
+    if output_size == 0:
+        raise OutputFileAccessError(
+            f"Output file not created after optimizing. We probably ran "
+            f"out of disk space in the temporary folder: {tempfile.gettempdir()}."
+        )
+    ratio = input_size / output_size
+    savings = 1 - output_size / input_size
+    log.info(f"Optimize ratio: {ratio:.2f} savings: {(savings):.1%}")
+
+    if savings < 0:
+        log.info(
+            "Image optimization did not improve the file - "
+            "optimizations will not be used"
+        )
+        # We still need to save the file
+        with Pdf.open(input_file) as pike:
+            pike.remove_unreferenced_resources()
+            pike.save(output_file, **save_settings)
+    else:
+        safe_symlink(target_file, output_file)
+
+
+def main(infile, outfile, level, jobs=1):
+    from shutil import copy  # pylint: disable=import-outside-toplevel
+    from tempfile import TemporaryDirectory  # pylint: disable=import-outside-toplevel
+
+    class OptimizeOptions:
+        """Emulate ocrmypdf's options"""
+
+        def __init__(
+            self, input_file, jobs, optimize_, jpeg_quality, png_quality, jb2lossy
+        ):
+            self.input_file = input_file
+            self.jobs = jobs
+            self.optimize = optimize_
+            self.jpeg_quality = jpeg_quality
+            self.png_quality = png_quality
+            self.jbig2_page_group_size = 0
+            self.jbig2_lossy = jb2lossy
+            self.quiet = True
+            self.progress_bar = False
+
+    infile = Path(infile)
+    options = OptimizeOptions(
+        input_file=infile,
+        jobs=jobs,
+        optimize_=int(level),
+        jpeg_quality=0,  # Use default
+        png_quality=0,
+        jb2lossy=False,
+    )
+
+    with TemporaryDirectory() as td:
+        context = PdfContext(options, td, infile, None, None)
+        tmpout = Path(td) / 'out.pdf'
+        optimize(
+            infile,
+            tmpout,
+            context,
+            dict(
+                compress_streams=True,
+                preserve_pdfa=True,
+                object_stream_mode=ObjectStreamMode.generate,
+            ),
+        )
+        copy(fspath(tmpout), fspath(outfile))
+
+
+if __name__ == '__main__':
+    main(sys.argv[1], sys.argv[2], sys.argv[3])