Merge api (without plugins)
This commit is contained in:
James R. Barlow
+162
-65
@@ -1,16 +1,34 @@
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=================
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Advanced features
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=================
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Control of unpaper
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------------------
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==================
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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.
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OCRmyPDF uses ``unpaper`` to provide the implementation of the
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``--clean`` and ``--clean-final`` arguments.
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`unpaper <https://github.com/Flameeyes/unpaper/blob/master/doc/basic-concepts.md>`__
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provides a variety of image processing filters to improve images.
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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.
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By default, OCRmyPDF uses only ``unpaper`` arguments that were found to
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be safe to use on almost all files without having to inspect every page
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of the file afterwards. This is particularly true when only ``--clean``
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is used, since that instructs OCRmyPDF to only clean the image before
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OCR and not the final image.
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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.
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However, if you wish to use the more aggressive options in ``unpaper``,
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you may use ``--unpaper-args '...'`` to override the OCRmyPDF's defaults
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and forward other arguments to unpaper. This option will forward
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arguments to ``unpaper`` without any knowledge of what that program
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considers to be valid arguments. The string of arguments must be quoted
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as shown in the examples below. No filename arguments may be included.
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OCRmyPDF will assume it can append input and output filename of
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intermediate images to the ``--unpaper-args`` string.
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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.
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In this example, we tell ``unpaper`` to expect two pages of text on a
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sheet (image), such as occurs when two facing pages of a book are
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scanned. ``unpaper`` uses this information to deskew each independently
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and clean up the margins of both.
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.. code-block:: bash
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@@ -19,40 +37,71 @@ In this example, we tell ``unpaper`` to expect two pages of text on a sheet (ima
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.. warning::
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Some ``unpaper`` features will reposition text within the image. ``--clean-final`` is recommended to avoid this issue.
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Some ``unpaper`` features will reposition text within the image.
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``--clean-final`` is recommended to avoid this issue.
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.. warning::
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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.
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Some ``unpaper`` features cause multiple input or output files to be
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consumed or produced. OCRmyPDF requires ``unpaper`` to consume one
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file and produce one file. An deviation from that condition will
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result in errors.
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.. note::
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``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.
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``unpaper`` uses uncompressed PBM/PGM/PPM files for its intermediate
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files. For large images or documents, it can take a lot of temporary
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disk space.
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Control of OCR options
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----------------------
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======================
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OCRmyPDF provides many features to control the behavior of the OCR engine, Tesseract.
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OCRmyPDF provides many features to control the behavior of the OCR
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engine, Tesseract.
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When OCR is skipped
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"""""""""""""""""""
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-------------------
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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.
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If a page in a PDF seems to have text, by default OCRmyPDF will exit
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without modifying the PDF. This is to ensure that PDFs that were
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previously OCRed or were "born digital" rather than scanned are not
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processed.
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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.
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If ``--skip-text`` is issued, then no OCR will be performed on pages
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that already have text. The page will be copied to the output. This may
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be useful for documents that contain both "born digital" and scanned
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content, or to use OCRmyPDF to normalize and convert to PDF/A regardless
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of their contents.
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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.
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If ``--redo-ocr`` is issued, then a detailed text analysis is performed.
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Text is categorized as either visible or invisible. Invisible text (OCR)
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is stripped out. Then an image of each page is created with visible text
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masked out. The page image is sent for OCR, and any additional text is
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inserted as OCR. If a file contains a mix of text and bitmap images that
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contain text, OCRmyPDF will locate the additional text in images without
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disrupting the existing text.
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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.
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If ``--force-ocr`` is issued, then all pages will be rasterized to
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images, discarding any hidden OCR text, and rasterizing any printable
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text. This is useful for redoing OCR, for fixing OCR text with a damaged
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character map (text is selectable but not searchable), and destroying
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redacted information. Any forms and vector graphics will be rasterized
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as well.
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Time and image size limits
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""""""""""""""""""""""""""
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--------------------------
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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.
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By default, OCRmyPDF permits tesseract to run for three minutes (180
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seconds) per page. This is usually more than enough time to find all
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text on a reasonably sized page with modern hardware.
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If a page is skipped, it will be inserted without OCR. If preprocessing was requested, the preprocessed image layer will be inserted.
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If a page is skipped, it will be inserted without OCR. If preprocessing
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was requested, the preprocessed image layer will be inserted.
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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.)
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If you want to adjust the amount of time spent on OCR, change
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``--tesseract-timeout``. You can also automatically skip images that
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exceed a certain number of megapixels with ``--skip-big``. (A 300 DPI,
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8.5×11" page is 8.4 megapixels.)
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.. code-block:: bash
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@@ -60,21 +109,27 @@ If you want to adjust the amount of time spent on OCR, change ``--tesseract-time
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ocrmypdf --tesseract-timeout 300 --skip-big 50 bigfile.pdf output.pdf
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Overriding default tesseract
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""""""""""""""""""""""""""""
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----------------------------
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OCRmyPDF checks the system ``PATH`` for the ``tesseract`` binary.
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Some relevant environment variables that influence Tesseract's behavior include:
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Some relevant environment variables that influence Tesseract's behavior
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include:
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.. envvar:: TESSDATA_PREFIX
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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.
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Overrides the path to Tesseract's data files. This can allow
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simultaneous installation of the "best" and "fast" training data
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sets. OCRmyPDF does not manage this environment variable.
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.. envvar:: OMP_THREAD_LIMIT
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Controls the number of threads Tesseract will use. OCRmyPDF will manage this environment if it is not already set. (Currently, it will set it to 1 because this gives the best results in testing.)
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Controls the number of threads Tesseract will use. OCRmyPDF will
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manage this environment if it is not already set. (Currently, it will
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set it to 1 because this gives the best results in testing.)
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For example, if you have a development build of Tesseract don't wish to use the system installation, you can launch OCRmyPDF as follows:
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For example, if you have a development build of Tesseract don't wish to
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use the system installation, you can launch OCRmyPDF as follows:
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.. code-block:: bash
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@@ -83,26 +138,33 @@ For example, if you have a development build of Tesseract don't wish to use the
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TESSDATA_PREFIX=/home/user/src/tesseract \
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ocrmypdf input.pdf output.pdf
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In this example ``TESSDATA_PREFIX`` is required to redirect Tesseract to an alternate folder for its "tessdata" files.
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In this example ``TESSDATA_PREFIX`` is required to redirect Tesseract to
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an alternate folder for its "tessdata" files.
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Overriding other support programs
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"""""""""""""""""""""""""""""""""
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---------------------------------
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In addition to tesseract, OCRmyPDF uses the following external binaries:
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* ``gs`` (Ghostscript)
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* ``unpaper``
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* ``qpdf``
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In each case OCRmyPDF will search the ``PATH`` environment variable to locate the binaries.
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- ``gs`` (Ghostscript)
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- ``unpaper``
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- ``qpdf``
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In each case OCRmyPDF will search the ``PATH`` environment variable to
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locate the binaries.
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Changing tesseract configuration variables
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""""""""""""""""""""""""""""""""""""""""""
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------------------------------------------
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You can override tesseract's default `control parameters <https://github.com/tesseract-ocr/tesseract/wiki/ControlParams>`_ with a configuration file.
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You can override tesseract's default `control
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parameters <https://github.com/tesseract-ocr/tesseract/wiki/ControlParams>`__
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with a configuration file.
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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).
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As an example, this configuration will disable Tesseract's dictionary
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for current language. Normally the dictionary is helpful for
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interpolating words that are unclear, but it may interfere with OCR if
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the document does not contain many words (for example, a list of part
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numbers).
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Create a file named "no-dict.cfg" with these contents:
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@@ -120,11 +182,11 @@ then run ocrmypdf as follows (along with any other desired arguments):
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.. warning::
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Some combinations of control parameters will break Tesseract or break assumptions that OCRmyPDF makes about Tesseract's output.
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Some combinations of control parameters will break Tesseract or break
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assumptions that OCRmyPDF makes about Tesseract's output.
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Changing the PDF renderer
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-------------------------
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=========================
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rasterizing
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Converting a PDF to an image for display.
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@@ -132,42 +194,63 @@ rasterizing
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rendering
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Creating a new PDF from other data (such as an existing PDF).
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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``.
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OCRmyPDF has these PDF renderers: ``sandwich`` and ``hocr``. The
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renderer may be selected using ``--pdf-renderer``. The default is
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``auto`` which lets OCRmyPDF select the renderer to use. Currently,
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``auto`` always selects ``sandwich``.
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The ``sandwich`` renderer
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"""""""""""""""""""""""""
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-------------------------
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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.
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The ``sandwich`` renderer uses Tesseract's new text-only PDF feature,
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which produces a PDF page that lays out the OCR in invisible text. This
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page is then "sandwiched" onto the original PDF page, allowing lossless
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application of OCR even to PDF pages that contain other vector objects.
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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.
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Currently this is the best renderer for most uses, however it is
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implemented in Tesseract so OCRmyPDF cannot influence it. Currently some
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problematic PDF viewers like Mozilla PDF.js and macOS Preview have
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problems with segmenting its text output, and
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mightrunseveralwordstogether.
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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.
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When image preprocessing features like ``--deskew`` are used, the
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original PDF will be rendered as a full page and the OCR layer will be
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placed on top.
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The ``hocr`` renderer
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"""""""""""""""""""""
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---------------------
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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.
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The ``hocr`` renderer works with older versions of Tesseract. The image
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layer is copied from the original PDF page if possible, avoiding
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potentially lossy transcoding or loss of other PDF information. If
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preprocessing is specified, then the image layer is a new PDF.
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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. Pull requests to improve the situation are welcome.
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Unlike ``sandwich`` this renderer is implemented within OCRmyPDF; anyone
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looking to customize how OCR is presented should look here. A major
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disadvantage of this renderer is it not capable of correctly handling
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text outside the Latin alphabet. Pull requests to improve the situation
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are welcome.
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Currently, this renderer has the best compatibility with Mozilla's PDF.js viewer.
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Currently, this renderer has the best compatibility with Mozilla's
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PDF.js viewer.
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This works in all versions of Tesseract.
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The ``tesseract`` renderer
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""""""""""""""""""""""""""
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--------------------------
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The ``tesseract`` renderer was removed. OCRmyPDF's new approach to text layer grafting makes it functionally equivalent to ``sandwich``.
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The ``tesseract`` renderer was removed. OCRmyPDF's new approach to text
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layer grafting makes it functionally equivalent to ``sandwich``.
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Return code policy
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------------------
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==================
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OCRmyPDF writes all messages to ``stderr``. ``stdout`` is reserved for piping
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output files. ``stdin`` is reserved for piping input files.
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OCRmyPDF writes all messages to ``stderr``. ``stdout`` is reserved for
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piping output files. ``stdin`` is reserved for piping input files.
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The return codes generated by the OCRmyPDF are considered part of the stable
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user interface. They may be imported from ``ocrmypdf.exceptions``.
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The return codes generated by the OCRmyPDF are considered part of the
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stable user interface. They may be imported from
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``ocrmypdf.exceptions``.
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.. list-table:: Return codes
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:widths: 5 35 60
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@@ -218,22 +301,36 @@ user interface. They may be imported from ``ocrmypdf.exceptions``.
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Debugging the intermediate files
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--------------------------------
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================================
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OCRmyPDF normally saves its intermediate results to a temporary folder and deletes this folder when it exits, whether it succeeded or failed.
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OCRmyPDF normally saves its intermediate results to a temporary folder
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and deletes this folder when it exits, whether it succeeded or failed.
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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:
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If the ``-k`` argument is issued on the command line, OCRmyPDF will keep
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the temporary folder and print the location, whether it succeeded or
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failed (provided the Python interpreter did not crash). An example
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message is:
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.. code-block:: none
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Temporary working files saved at:
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Temporary working files retained at:
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/tmp/com.github.ocrmypdf.u20wpz07
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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:
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The organization of this folder is an implementation detail and subject
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to change between releases. However the general organization is that
|
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working files on a per page basis have the page number as a prefix
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(starting with page 1), an infix indicates the processing stage, and a
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suffix indicates the file type. Some important files include:
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* ``.page.png`` - what the input page looks like
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* ``.image`` - the image we will show the user if we are in a mode that changes the final appearance; may be in one of several image formats
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* ``.text.pdf`` - the OCR file; this will load as a blank page but should have visible text if checked with a tool like pdftotext or pdfminder.six
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* ``.ocr.png`` - the file that is sent to Tesseract for OCR; depending on arguments this may differ from the presentation image
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* ``layers.rendered.pdf`` - the composite PDF, before metadata repair and optimization
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* ``images/*`` - images extracted during the optimization process; here the prefix indicates a PDF object ID not a page number
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- ``.page.png`` - what the input page looks like
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- ``.image`` - the image we will show the user if we are in a mode that
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changes the final appearance; may be in one of several image formats
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- ``.text.pdf`` - the OCR file; this will load as a blank page but
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should have visible text if checked with a tool like pdftotext or
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pdfminder.six
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- ``.ocr.png`` - the file that is sent to Tesseract for OCR; depending
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on arguments this may differ from the presentation image
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- ``layers.rendered.pdf`` - the composite PDF, before metadata repair
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and optimization
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- ``images/*`` - images extracted during the optimization process; here
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the prefix indicates a PDF object ID not a page number
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+101
@@ -0,0 +1,101 @@
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======================
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||||
Using the OCRmyPDF API
|
||||
======================
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OCRmyPDF originated as a command line program and continues to have this
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legacy, but parts of it can be imported and used in other Python
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applications.
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Some applications may want to consider running ocrmypdf from a
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subprocess call anyway, as this provides isolation of its activities.
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Example
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||||
=======
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||||
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||||
OCRmyPDF one high-level function to run its main engine from an
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application. The parameters are symmetric to the command line arguments
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||||
and largely have the same functions.
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||||
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.. code-block:: python
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||||
import ocrmypdf
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ocrmypdf.ocr('input.pdf', 'output.pdf', deskew=True)
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With a few exceptions, all of the command line arguments are available
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and may be passed as equivalent keywords.
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A few differences are that ``verbose`` and ``quiet`` are not available.
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Instead, output should be managed by configuring logging.
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||||
Parent process requirements
|
||||
---------------------------
|
||||
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||||
The :func:`ocrmypdf.run` function runs OCRmyPDF similar to command line
|
||||
execution. To do this, it will: - create a monitoring thread - create
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||||
worker processes (forking itself) - manage the signal flags of worker
|
||||
processes 0 execute other subprocesses (forking and executing other
|
||||
programs)
|
||||
|
||||
The Python process that calls ``ocrmypdf.ocr()`` must be sufficiently
|
||||
privileged to perform these actions. If it is not, ``ocrmypdf()`` will
|
||||
fail.
|
||||
|
||||
There is no currently no option to manage how jobs are scheduled other
|
||||
than the argument ``jobs=`` which will limit the number of worker
|
||||
processes.
|
||||
|
||||
Forking a child process to call ``ocrmypdf.ocr()`` is suggested. That
|
||||
way your application will survive and remain interactive even if
|
||||
OCRmyPDF does not.
|
||||
|
||||
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.
|
||||
|
||||
Exceptions
|
||||
----------
|
||||
|
||||
OCRmyPDF may throw standard Python exceptions, ``ocrmypdf.exceptions.*``
|
||||
exceptions, some exceptions related to multiprocessing, and
|
||||
``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.run
|
||||
|
||||
.. autoclass:: ocrmypdf.Verbosity
|
||||
:members:
|
||||
:undoc-members:
|
||||
|
||||
.. autoclass:: ocrmypdf.ExitCode
|
||||
:members:
|
||||
:undoc-members:
|
||||
|
||||
.. autofunction:: ocrmypdf.configure_logging
|
||||
+206
-168
@@ -1,225 +1,263 @@
|
||||
================
|
||||
Batch processing
|
||||
================
|
||||
|
||||
This article provides information about running OCRmyPDF on multiple files or configuring it as a service triggered by file system events.
|
||||
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.
|
||||
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.
|
||||
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.
|
||||
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.
|
||||
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
|
||||
parallel --tag -j 2 ocrmypdf '{}' 'output/{}' ::: *.pdf
|
||||
|
||||
OCRmyPDF automatically repairs PDFs before parsing and gathering information from them.
|
||||
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
|
||||
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):
|
||||
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-alpine '<container dir>/{}' '<container dir>/{}' \;
|
||||
find . -printf '%p' -name '*.pdf' -exec docker run --rm -v <host dir>:<container dir> jbarlow83/ocrmypdf-alpine '<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.
|
||||
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 '{}' '{}'
|
||||
|
||||
find . -name '*.pdf' | parallel --tag -j 2 ocrmypdf '{}' '{}'
|
||||
|
||||
Sample script
|
||||
"""""""""""""
|
||||
-------------
|
||||
|
||||
This user contributed script also provides an example of batch processing.
|
||||
This user contributed script also provides an example of batch
|
||||
processing.
|
||||
|
||||
.. code-block:: python
|
||||
|
||||
#!/usr/bin/env python3
|
||||
# Walk through directory tree, replacing all files with OCR'd version
|
||||
# Contributed by DeliciousPickle@github
|
||||
#!/usr/bin/env python3
|
||||
# Walk through directory tree, replacing all files with OCR'd version
|
||||
# Contributed by DeliciousPickle@github
|
||||
|
||||
import logging
|
||||
import os
|
||||
import subprocess
|
||||
import sys
|
||||
import logging
|
||||
import os
|
||||
import subprocess
|
||||
import sys
|
||||
|
||||
script_dir = os.path.dirname(os.path.realpath(__file__))
|
||||
print(script_dir + '/ocr-tree.py: Start')
|
||||
script_dir = os.path.dirname(os.path.realpath(__file__))
|
||||
print(script_dir + '/ocr-tree.py: Start')
|
||||
|
||||
if len(sys.argv) > 1:
|
||||
start_dir = sys.argv[1]
|
||||
else:
|
||||
start_dir = '.'
|
||||
if len(sys.argv) > 1:
|
||||
start_dir = sys.argv[1]
|
||||
else:
|
||||
start_dir = '.'
|
||||
|
||||
if len(sys.argv) > 2:
|
||||
log_file = sys.argv[2]
|
||||
else:
|
||||
log_file = script_dir + '/ocr-tree.log'
|
||||
if len(sys.argv) > 2:
|
||||
log_file = sys.argv[2]
|
||||
else:
|
||||
log_file = script_dir + '/ocr-tree.log'
|
||||
|
||||
logging.basicConfig(
|
||||
level=logging.INFO, format='%(asctime)s %(message)s',
|
||||
filename=log_file, filemode='w')
|
||||
|
||||
for dir_name, subdirs, file_list in os.walk(start_dir):
|
||||
logging.info('\n')
|
||||
logging.info(dir_name + '\n')
|
||||
os.chdir(dir_name)
|
||||
for filename in file_list:
|
||||
file_ext = os.path.splitext(filename)[1]
|
||||
if file_ext == '.pdf':
|
||||
full_path = dir_name + '/' + filename
|
||||
print(full_path)
|
||||
cmd = ["ocrmypdf", "--deskew", filename, filename]
|
||||
logging.info(cmd)
|
||||
proc = subprocess.run(
|
||||
cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
|
||||
result = proc.stdout
|
||||
if proc.returncode == 6:
|
||||
print("Skipped document because it already contained text")
|
||||
elif proc.returncode == 0:
|
||||
print("OCR complete")
|
||||
logging.info(result)
|
||||
|
||||
API
|
||||
"""
|
||||
|
||||
OCRmyPDF is currently supported as a command line interface. This means that even if you are using OCRmyPDF in a Python script, you should run it in a subprocess rather importing the ocrmypdf package.
|
||||
|
||||
The reason for this limitation is that the `ruffus <https://github.com/bunbun/ruffus/>`_ library that OCRmyPDF depends on is unfortunately not reentrant. OCRmyPDF works by defining each operation it does as a ruffus task that takes one or more files as input and generates one or more files as output. As such ruffus is fairly fundamental.
|
||||
|
||||
(If you find individual functions implemented in OCRmyPDF useful (such as ``ocrmypdf.pdfinfo``), you can use these if you wish to.)
|
||||
logging.basicConfig(
|
||||
level=logging.INFO, format='%(asctime)s %(message)s',
|
||||
filename=log_file, filemode='w')
|
||||
|
||||
for dir_name, subdirs, file_list in os.walk(start_dir):
|
||||
logging.info('\n')
|
||||
logging.info(dir_name + '\n')
|
||||
os.chdir(dir_name)
|
||||
for filename in file_list:
|
||||
file_ext = os.path.splitext(filename)[1]
|
||||
if file_ext == '.pdf':
|
||||
full_path = dir_name + '/' + filename
|
||||
print(full_path)
|
||||
cmd = ["ocrmypdf", "--deskew", filename, filename]
|
||||
logging.info(cmd)
|
||||
proc = subprocess.run(
|
||||
cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
|
||||
result = proc.stdout
|
||||
if proc.returncode == 6:
|
||||
print("Skipped document because it already contained text")
|
||||
elif proc.returncode == 0:
|
||||
print("OCR complete")
|
||||
logging.info(result)
|
||||
|
||||
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.
|
||||
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.
|
||||
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.
|
||||
|
||||
.. code-block:: python
|
||||
|
||||
#!/bin/env python3
|
||||
# Contributed by github.com/Enantiomerie
|
||||
#!/bin/env python3
|
||||
# Contributed by github.com/Enantiomerie
|
||||
|
||||
# script needs 2 arguments
|
||||
# 1. source dir with *.pdf - default is location of script
|
||||
# 2. move dir where *.pdf and *_OCR.pdf are moved to
|
||||
# script needs 2 arguments
|
||||
# 1. source dir with *.pdf - default is location of script
|
||||
# 2. move dir where *.pdf and *_OCR.pdf are moved to
|
||||
|
||||
import logging
|
||||
import os
|
||||
import subprocess
|
||||
import sys
|
||||
import time
|
||||
import shutil
|
||||
import logging
|
||||
import os
|
||||
import subprocess
|
||||
import sys
|
||||
import time
|
||||
import shutil
|
||||
|
||||
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')
|
||||
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 = '.'
|
||||
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('\n')
|
||||
logging.info(dir_name + '\n')
|
||||
os.chdir(dir_name)
|
||||
for filename in file_list:
|
||||
file_ext = os.path.splitext(filename)[1]
|
||||
if file_ext == '.pdf':
|
||||
full_path = dir_name + '/' + filename
|
||||
file_noext = os.path.splitext(filename)[0]
|
||||
timestamp_OCR = time.strftime("%Y-%m-%d-%H%M_OCR_")
|
||||
filename_OCR = timestamp_OCR + file_noext + '.pdf'
|
||||
docker_mount = dir_name + ':/home/docker'
|
||||
# create string for pdf processing
|
||||
# diskstation needs a user:group docker:docker. find uid:gid of your diskstation docker:docker with id docker.
|
||||
# use this uid:gid in -u flag
|
||||
# rw rights for docker:docker at source dir are also necessary
|
||||
# the script is processed as root user via chron
|
||||
cmd = ['docker', 'run', '--rm', '-v', docker_mount, '-u=1030:65538', 'jbarlow83/ocrmypdf', , '--deskew' , filename, filename_OCR]
|
||||
logging.info(cmd)
|
||||
proc = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
|
||||
result = proc.stdout.read()
|
||||
logging.info(result)
|
||||
full_path_OCR = dir_name + '/' + filename_OCR
|
||||
os.chmod(full_path_OCR, 0o666)
|
||||
os.chmod(full_path, 0o666)
|
||||
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')
|
||||
for dir_name, subdirs, file_list in os.walk(start_dir):
|
||||
logging.info('\n')
|
||||
logging.info(dir_name + '\n')
|
||||
os.chdir(dir_name)
|
||||
for filename in file_list:
|
||||
file_ext = os.path.splitext(filename)[1]
|
||||
if file_ext == '.pdf':
|
||||
full_path = dir_name + '/' + filename
|
||||
file_noext = os.path.splitext(filename)[0]
|
||||
timestamp_OCR = time.strftime("%Y-%m-%d-%H%M_OCR_")
|
||||
filename_OCR = timestamp_OCR + file_noext + '.pdf'
|
||||
docker_mount = dir_name + ':/home/docker'
|
||||
# create string for pdf processing
|
||||
# diskstation needs a user:group docker:docker. find uid:gid of your diskstation docker:docker with id docker.
|
||||
# use this uid:gid in -u flag
|
||||
# rw rights for docker:docker at source dir are also necessary
|
||||
# the script is processed as root user via chron
|
||||
cmd = ['docker', 'run', '--rm', '-v', docker_mount, '-u=1030:65538', 'jbarlow83/ocrmypdf', , '--deskew' , filename, filename_OCR]
|
||||
logging.info(cmd)
|
||||
proc = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
|
||||
result = proc.stdout.read()
|
||||
logging.info(result)
|
||||
full_path_OCR = dir_name + '/' + filename_OCR
|
||||
os.chmod(full_path_OCR, 0o666)
|
||||
os.chmod(full_path, 0o666)
|
||||
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')
|
||||
|
||||
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
|
||||
---------------------
|
||||
|
||||
To set up a "hot folder" that will trigger OCR for every file inserted, use a program like Python `watchdog <https://pypi.python.org/pypi/watchdog>`_ (supports all major OS).
|
||||
|
||||
One could then configure a scanner to automatically place scanned files in a hot folder, so that they will be queued for OCR and copied to the destination.
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
pip install watchdog
|
||||
|
||||
watchdog installs the command line program ``watchmedo``, which can be told to run ``ocrmypdf`` on any .pdf added to the current directory (``.``) and place the result in the previously created ``out/`` folder.
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
cd hot-folder
|
||||
mkdir out
|
||||
watchmedo shell-command \
|
||||
--patterns="*.pdf" \
|
||||
--ignore-directories \
|
||||
--command='ocrmypdf "${watch_src_path}" "out/${watch_src_path}" ' \
|
||||
. # don't forget the final dot
|
||||
|
||||
For more complex behavior you can write a Python script around to use the watchdog API.
|
||||
|
||||
On file servers, you could configure watchmedo as a system service so it will run all the time.
|
||||
|
||||
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
|
||||
""""""""""""
|
||||
|
||||
* `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:
|
||||
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.
|
||||
|
||||
.. image:: images/macos-workflow.png
|
||||
:alt: Example macOS Automator script
|
||||
Hot (watched) folders
|
||||
=====================
|
||||
|
||||
To set up a "hot folder" that will trigger OCR for every file inserted,
|
||||
use a program like Python
|
||||
`watchdog <https://pypi.python.org/pypi/watchdog>`__ (supports all major
|
||||
OS).
|
||||
|
||||
One could then configure a scanner to automatically place scanned files
|
||||
in a hot folder, so that they will be queued for OCR and copied to the
|
||||
destination.
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
pip install watchdog
|
||||
|
||||
watchdog installs the command line program ``watchmedo``, which can be
|
||||
told to run ``ocrmypdf`` on any .pdf added to the current directory
|
||||
(``.``) and place the result in the previously created ``out/`` folder.
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
cd hot-folder
|
||||
mkdir out
|
||||
watchmedo shell-command \
|
||||
--patterns="*.pdf" \
|
||||
--ignore-directories \
|
||||
--command='ocrmypdf "${watch_src_path}" "out/${watch_src_path}" ' \
|
||||
. # don't forget the final dot
|
||||
|
||||
For more complex behavior you can write a Python script around to use
|
||||
the watchdog API.
|
||||
|
||||
On file servers, you could configure watchmedo as a system service so it
|
||||
will run all the time.
|
||||
|
||||
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
|
||||
------------
|
||||
|
||||
- `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:
|
||||
|
||||
|Example macOS Automator script|
|
||||
|
||||
You may customize the command sent to ocrmypdf.
|
||||
|
||||
.. |Example macOS Automator script| image:: images/macos-workflow.png
|
||||
|
||||
+1
-3
@@ -30,9 +30,7 @@
|
||||
# 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.mathjax',
|
||||
]
|
||||
extensions = ['sphinx.ext.napoleon']
|
||||
|
||||
# Add any paths that contain templates here, relative to this directory.
|
||||
templates_path = ['_templates']
|
||||
|
||||
+135
-65
@@ -1,11 +1,12 @@
|
||||
========
|
||||
Cookbook
|
||||
========
|
||||
|
||||
Basic examples
|
||||
--------------
|
||||
==============
|
||||
|
||||
Help!
|
||||
^^^^^
|
||||
-----
|
||||
|
||||
ocrmypdf has built-in help.
|
||||
|
||||
@@ -13,30 +14,29 @@ ocrmypdf has built-in help.
|
||||
|
||||
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.
|
||||
|
||||
@@ -45,48 +45,58 @@ The file will only be overwritten if OCRmyPDF is successful.
|
||||
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.
|
||||
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.
|
||||
You can increase (decrease) the parameter ``--rotate-pages-threshold``
|
||||
to make page rotation more (less) aggressive.
|
||||
|
||||
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.
|
||||
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.
|
||||
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>`.
|
||||
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.
|
||||
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".
|
||||
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
|
||||
|
||||
OCR images, not PDFs
|
||||
^^^^^^^^^^^^^^^^^^^^
|
||||
--------------------
|
||||
|
||||
Option: use Tesseract
|
||||
"""""""""""""""""""""
|
||||
~~~~~~~~~~~~~~~~~~~~~
|
||||
|
||||
If you are starting with images, you can just use Tesseract directly to convert images to PDFs:
|
||||
If you are starting with images, you can just use Tesseract directly to
|
||||
convert images to PDFs:
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
@@ -97,62 +107,88 @@ If you are starting with images, you can just use Tesseract directly to convert
|
||||
# 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.
|
||||
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.
|
||||
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.
|
||||
``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).
|
||||
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.
|
||||
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.
|
||||
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.
|
||||
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. Skew determination and correction is performed using `Postl's variance of line sums <http://www.leptonica.com/skew-measurement.html>`_ algorithm as implemented in `Leptonica <http://www.leptonica.com/index.html>`_.
|
||||
|
||||
* ``--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.
|
||||
|
||||
* ``--mask-barcodes`` will suppress any barcodes detected in a page image. Barcodes are known to confuse Tesseract OCR and interfere with the recognition of text on the same baseline as a barcode. The output file will contain the unaltered image of the barcode.
|
||||
- ``--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. Skew determination and correction is
|
||||
performed using `Postl's variance of line
|
||||
sums <http://www.leptonica.com/skew-measurement.html>`__ algorithm as
|
||||
implemented in `Leptonica <http://www.leptonica.com/index.html>`__.
|
||||
- ``--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.
|
||||
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.
|
||||
``--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:
|
||||
|
||||
@@ -160,55 +196,83 @@ Deskew:
|
||||
|
||||
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).
|
||||
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.
|
||||
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
|
||||
|
||||
|
||||
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.)
|
||||
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.
|
||||
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.
|
||||
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.
|
||||
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.
|
||||
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`_ features can improve 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.
|
||||
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).
|
||||
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.
|
||||
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.
|
||||
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
|
||||
@@ -227,9 +291,15 @@ The ``--optimize N`` (short form ``-O``) argument controls optimization, where `
|
||||
* - ``--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.
|
||||
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.
|
||||
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
|
||||
|
||||
|
||||
+104
-84
@@ -1,155 +1,175 @@
|
||||
=====================
|
||||
OCRmyPDF Docker image
|
||||
=====================
|
||||
|
||||
OCRmyPDF is also available in a Docker image that packages recent versions of all dependencies.
|
||||
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.
|
||||
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, and temporary storage space.
|
||||
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 have `Docker <https://docs.docker.com/>`__ installed on your
|
||||
system, you can install a Docker image of the latest release.
|
||||
|
||||
The recommended OCRmyPDF Docker image is currently named ``ocrmypdf-alpine``:
|
||||
The recommended OCRmyPDF Docker image is currently named
|
||||
``ocrmypdf-alpine``:
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
docker pull jbarlow83/ocrmypdf-alpine
|
||||
docker pull jbarlow83/ocrmypdf-alpine
|
||||
|
||||
Follow the Docker installation instructions for your platform. If you can run this command successfully, your system is ready to download and execute the image:
|
||||
Follow the Docker installation instructions for your platform. If you
|
||||
can run this command successfully, your system is ready to download and
|
||||
execute the image:
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
docker run hello-world
|
||||
docker run hello-world
|
||||
|
||||
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:
|
||||
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")
|
||||
# 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 $(docker-machine env "yourVM")
|
||||
|
||||
Using the Docker image on the command line
|
||||
------------------------------------------
|
||||
==========================================
|
||||
|
||||
**Unlike typical Docker containers**, in this mode we are using the OCRmyPDF Docker container is intended to be emphemeral – it runs for one OCR job and then terminates, just like a command line program. We are using Docker as a way of delivering an application, not a server.
|
||||
**Unlike typical Docker containers**, in this mode we are using the
|
||||
OCRmyPDF Docker container is intended to be emphemeral – it runs for one
|
||||
OCR job and then terminates, just like a command line program. We are
|
||||
using Docker as a way of delivering an application, not a server.
|
||||
|
||||
To start a Docker container (instance of the image):
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
docker tag jbarlow83/ocrmypdf-alpine ocrmypdf
|
||||
docker run --rm ocrmypdf (... all other arguments here...)
|
||||
docker tag jbarlow83/ocrmypdf-alpine ocrmypdf
|
||||
docker run --rm -i ocrmypdf (... all other arguments here...)
|
||||
|
||||
For convenience, create a shell alias to hide the Docker command:
|
||||
For convenience, create a shell alias to hide the Docker command. It is
|
||||
easier to send the input file to file stdin and read the output from
|
||||
stdout – this avoids the occasionally messy permission issues with
|
||||
Docker entirely.
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
alias ocrmypdf='docker run --rm -v "$(pwd):/home/docker" ocrmypdf'
|
||||
ocrmypdf --version # runs docker version
|
||||
alias ocrmypdf='docker run --rm -i ocrmypdf'
|
||||
ocrmypdf --version # runs docker version
|
||||
ocrmypdf <input.pdf >output.pdf
|
||||
|
||||
Or in the wonderful `fish shell <https://fishshell.com/>`_:
|
||||
Or in the wonderful `fish shell <https://fishshell.com/>`__:
|
||||
|
||||
.. code-block:: fish
|
||||
|
||||
alias ocrmypdf 'docker run --rm ocrmypdf'
|
||||
funcsave ocrmypdf
|
||||
alias ocrmypdf 'docker run --rm ocrmypdf'
|
||||
funcsave ocrmypdf
|
||||
|
||||
Alternately, you could mount the local current working directory as a
|
||||
Docker volume:
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
docker run --rm -v $(pwd):/data ocrmypdf /data/input.pdf /data/output.pdf
|
||||
|
||||
.. _docker-lang-packs:
|
||||
|
||||
Adding languages to the Docker image
|
||||
------------------------------------
|
||||
====================================
|
||||
|
||||
By default the Docker image includes English, German and Simplified Chinese, 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:
|
||||
By default the Docker image includes English, German and Simplified
|
||||
Chinese, 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-alpine
|
||||
FROM jbarlow83/ocrmypdf-alpine
|
||||
|
||||
# Add French
|
||||
RUN apk add tesseract-ocr-data-fra
|
||||
# Add French
|
||||
RUN apk add tesseract-ocr-data-fra
|
||||
|
||||
You can also copy training data to ``/usr/share/tessdata``.
|
||||
|
||||
Executing the test suite
|
||||
------------------------
|
||||
========================
|
||||
|
||||
The OCRmyPDF test suite is installed with image. To run it:
|
||||
The OCRmyPDF test suite is installed with image. To run it:
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
docker run --entrypoint python3 jbarlow83/ocrmypdf-alpine setup.py test
|
||||
docker run --entrypoint python3 jbarlow83/ocrmypdf-alpine setup.py test
|
||||
|
||||
Accessing the shell
|
||||
===================
|
||||
|
||||
``bash`` is not installed in the image. To use the busybox shell in the
|
||||
Docker image:
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
docker run -it --entrypoint busybox jbarlow83/ocrmypdf-alpine sh
|
||||
|
||||
Using the OCRmyPDF web service wrapper
|
||||
--------------------------------------
|
||||
======================================
|
||||
|
||||
The OCRmyPDF Docker image includes an example, barebones HTTP web service. The webservice may be launched as follows:
|
||||
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-alpine webservice.py
|
||||
docker run --entrypoint python3 -p 5000:5000 jbarlow83/ocrmypdf-alpine webservice.py
|
||||
|
||||
Unlike command line usage this program will open a socket and wait for connections.
|
||||
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. It cannot respond to clients while busy with OCR.
|
||||
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.
|
||||
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, a dependency of OCRmyPDF, is also licensed in this way.
|
||||
Unlike the rest of OCRmyPDF, this web service is licensed under the
|
||||
Affero GPLv3 (AGPLv3) since Ghostscript, a dependency of OCRmyPDF, 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>`.
|
||||
In addition to the above, please read our
|
||||
:ref:`general remarks on using OCRmyPDF as a service <ocr-service>`.
|
||||
|
||||
Legacy Ubuntu Docker images
|
||||
---------------------------
|
||||
Ubuntu-based Docker image
|
||||
=========================
|
||||
|
||||
Previously OCRmyPDF was delivered in several Docker images for different purposes, based on Ubuntu.
|
||||
|
||||
The Ubuntu-based images will be maintained for some time but should not be used for new deployments. They are as follows:
|
||||
|
||||
.. list-table::
|
||||
:widths: auto
|
||||
:header-rows: 1
|
||||
|
||||
* - Image name
|
||||
- Download command
|
||||
- Notes
|
||||
* - ocrmypdf
|
||||
- ``docker pull jbarlow83/ocrmypdf``
|
||||
- Latest ocrmypdf with Tesseract 4.0.0-beta1 on Ubuntu 18.04. Includes English, French, German, Spanish, Portugeuse and Simplified Chinese.
|
||||
* - ocrmypdf-polyglot
|
||||
- ``docker pull jbarlow83/ocrmypdf-polyglot``
|
||||
- As above, with all available language packs.
|
||||
* - ocrmypdf-webservice
|
||||
- ``docker pull jbarlow83/ocrmypdf-webservice``
|
||||
- All language packs, and a simple HTTP wrapper allowing OCRmyPDF to be used as a web service. Note that this component is licensed under AGPLv3.
|
||||
|
||||
To execute the Ubuntu-based OCRmyPDF on a local file, you must `provide a writable volume to the Docker image <https://docs.docker.com/userguide/dockervolumes/>`_, and both the input and output file must be inside the writable volume. This limitation applies only to the legacy images.
|
||||
|
||||
This example command uses the current working directory as the writable volume:
|
||||
A Ubuntu-based OCRmyPDF image is also available. The main advantage this
|
||||
image offers is that it supports manylinux Python wheels (which are not
|
||||
supported on Alpine Linux). This may be useful for plugins.
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
docker run --rm -v "$(pwd):/home/docker" <other docker arguments> ocrmypdf <your arguments to ocrmypdf>
|
||||
|
||||
In this worked example, the current working directory contains an input file called ``test.pdf`` and the output will go to ``output.pdf``:
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
docker run --rm -v "$(pwd):/home/docker" ocrmypdf --skip-text test.pdf output.pdf
|
||||
|
||||
.. note:: The working directory should be a writable local volume or Docker may not have permission to access it.
|
||||
|
||||
Note that ``ocrmypdf`` has its own separate ``-v VERBOSITYLEVEL`` argument to control debug verbosity. All Docker arguments should before the ``ocrmypdf`` image name and all arguments to ``ocrmypdf`` should be listed after.
|
||||
|
||||
In some environments the permissions associated with Docker can be complex to configure. The process that executes Docker may end up not having the permissions to write the specified file system. In that case one can stream the file into and out of the Docker process and avoid all permission hassles, using ``-`` as the input and output filename:
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
docker run --rm -i ocrmypdf <other arguments to ocrmypdf> - - <input.pdf >output.pdf
|
||||
docker pull jbarlow83/ocrmypdf
|
||||
|
||||
+29
-15
@@ -1,33 +1,47 @@
|
||||
=====================
|
||||
Common error messages
|
||||
=====================
|
||||
|
||||
Page already has text
|
||||
---------------------
|
||||
=====================
|
||||
|
||||
.. code::
|
||||
.. code-block::
|
||||
|
||||
ERROR - 1: page already has text! – aborting (use --force-ocr to force OCR)
|
||||
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.
|
||||
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 --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.
|
||||
|
||||
Input file 'filename' is not a valid PDF
|
||||
----------------------------------------
|
||||
========================================
|
||||
|
||||
OCRmyPDF passes files through qpdf, a program that 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.
|
||||
OCRmyPDF passes files through qpdf, a program that 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 or pdftk:
|
||||
You can try rewriting the file with Ghostscript:
|
||||
|
||||
- ``gs -o output.pdf -dSAFER -sDEVICE=pdfwrite input.pdf``
|
||||
.. code-block:: bash
|
||||
|
||||
- ``pdftk input.pdf cat output output.pdf``
|
||||
gs -o output.pdf -dSAFER -sDEVICE=pdfwrite input.pdf
|
||||
|
||||
Sometimes Acrobat can repair PDFs with its `Preflight tool <https://helpx.adobe.com/acrobat/using/correcting-problem-areas-preflight-tool.html>`_.
|
||||
``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>`__.
|
||||
|
||||
Binary file not shown.
|
After Width: | Height: | Size: 31 KiB |
@@ -0,0 +1,75 @@
|
||||
<?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">
|
||||
<svg width="100%" height="100%" viewBox="0 0 503 227" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" xml:space="preserve" xmlns:serif="http://www.serif.com/" style="fill-rule:evenodd;clip-rule:evenodd;stroke-linecap:round;stroke-linejoin:round;stroke-miterlimit:1.5;">
|
||||
<g id="svg" transform="matrix(0.965977,0,0,0.807602,0,0)">
|
||||
<rect x="0" y="0" width="520" height="280" style="fill:white;"/>
|
||||
<g transform="matrix(1.03522,0,0,1.23823,-69.7528,-83.422)">
|
||||
<g transform="matrix(1,0,0,1,243.977,20.0703)">
|
||||
<g id="Page">
|
||||
<g transform="matrix(0.961773,0,0,1.05962,6.19811,-3.01071)">
|
||||
<path d="M328.5,97.682C328.5,96.465 327.983,95.296 327.056,94.418C320.026,87.758 289.442,58.78 282.228,51.944C281.251,51.019 279.901,50.496 278.49,50.496C264.493,50.496 188.083,50.496 167.339,50.496C164.468,50.496 162.141,52.609 162.141,55.214C162.141,83.051 162.141,225.565 162.141,253.4C162.141,256.005 164.468,258.117 167.338,258.117C192.242,258.117 299.159,258.117 323.538,258.117C326.278,258.117 328.5,256.101 328.5,253.613C328.5,229.268 328.5,113.896 328.5,97.682Z" style="fill:rgb(253,253,253);stroke:rgb(51,51,51);stroke-width:3.95px;"/>
|
||||
</g>
|
||||
<g id="Dog-ear" serif:id="Dog ear" transform="matrix(1,0,0,1,-4,2)">
|
||||
<path d="M277.072,48.496L277.072,93.848C277.072,95.172 277.598,96.441 278.534,97.377C279.47,98.313 280.739,98.839 282.063,98.839C294.548,98.839 326.141,98.839 326.141,98.839" style="fill:rgb(245,245,245);stroke:rgb(51,51,51);stroke-width:4px;"/>
|
||||
</g>
|
||||
</g>
|
||||
<g transform="matrix(1,0,0,1,-29.6816,-0.395178)">
|
||||
<g transform="matrix(1.00243,0,0,1.11818,-144.72,-8.80181)">
|
||||
<path d="M465.73,119.654C465.73,117.605 463.874,115.941 461.588,115.941L310.259,115.941C307.973,115.941 306.117,117.605 306.117,119.654L306.117,183.108C306.117,185.157 307.973,186.821 310.259,186.821L461.588,186.821C463.874,186.821 465.73,185.157 465.73,183.108L465.73,119.654Z" style="fill:rgb(248,0,0);stroke:white;stroke-width:3.77px;"/>
|
||||
</g>
|
||||
<g transform="matrix(1.24571,0,0,1.35864,116.812,84.3924)">
|
||||
<g transform="matrix(64,0,0,64,42.1437,77.6203)">
|
||||
<path d="M0.084,0L0.084,-0.68L0.297,-0.68C0.371,-0.68 0.434,-0.663 0.487,-0.63C0.54,-0.596 0.566,-0.54 0.566,-0.462C0.566,-0.385 0.538,-0.328 0.481,-0.292C0.424,-0.255 0.36,-0.237 0.288,-0.237L0.213,-0.237L0.213,0L0.084,0ZM0.293,-0.572L0.213,-0.572L0.213,-0.344L0.295,-0.344C0.334,-0.344 0.365,-0.353 0.389,-0.371C0.413,-0.388 0.426,-0.416 0.429,-0.454C0.429,-0.498 0.417,-0.529 0.393,-0.546C0.369,-0.563 0.336,-0.572 0.293,-0.572Z" style="fill:white;fill-rule:nonzero;"/>
|
||||
</g>
|
||||
<g transform="matrix(64,0,0,64,79.7117,77.6203)">
|
||||
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</svg>
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||||
|
After Width: | Height: | Size: 9.3 KiB |
+1
-5
@@ -1,8 +1,3 @@
|
||||
.. ocrmypdf documentation master file, created by
|
||||
sphinx-quickstart on Sun Sep 4 14:29:43 2016.
|
||||
You can adapt this file completely to your liking, but it should at least
|
||||
contain the root `toctree` directive.
|
||||
|
||||
OCRmyPDF documentation
|
||||
======================
|
||||
|
||||
@@ -27,6 +22,7 @@ PDF is the best format for storing and exchanging scanned documents. Unfortunat
|
||||
cookbook
|
||||
docker
|
||||
advanced
|
||||
api
|
||||
batch
|
||||
security
|
||||
errors
|
||||
|
||||
+186
-112
@@ -1,3 +1,4 @@
|
||||
===================
|
||||
Installing OCRmyPDF
|
||||
===================
|
||||
|
||||
@@ -18,10 +19,10 @@ installing the Python binary wheels.
|
||||
:local:
|
||||
|
||||
Installing on Linux
|
||||
-------------------
|
||||
===================
|
||||
|
||||
Debian and Ubuntu 16.10 or newer
|
||||
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
--------------------------------
|
||||
|
||||
.. |deb-stable| image:: https://repology.org/badge/version-for-repo/debian_stable/ocrmypdf.svg
|
||||
:alt: Debian 9 stable ("stretch")
|
||||
@@ -52,22 +53,33 @@ Debian and Ubuntu 16.10 or newer
|
||||
| |ubu-1710| |ubu-1804| |ubu-1810| |
|
||||
+-------------------------------------------+
|
||||
|
||||
Users of Debian 9 ("stretch") or later or Ubuntu 16.10 or later may simply
|
||||
Users of Debian 9 ("stretch") or later or Ubuntu 16.10 or later 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`_.
|
||||
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>`__.
|
||||
|
||||
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>`_.
|
||||
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`.
|
||||
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 29 or newer
|
||||
^^^^^^^^^^^^^^^^^^
|
||||
------------------
|
||||
|
||||
.. |fedora-29| image:: https://repology.org/badge/version-for-repo/fedora29/ocrmypdf.svg
|
||||
:alt: Fedora 29
|
||||
@@ -90,28 +102,28 @@ Users of Fedora 29 later may simply
|
||||
|
||||
dnf install ocrmypdf
|
||||
|
||||
For full details on version availability, check the `Fedora Package Tracker
|
||||
<https://apps.fedoraproject.org/packages/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`_.
|
||||
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>`_.
|
||||
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 18.04 LTS
|
||||
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
||||
-------------------------------------------------
|
||||
|
||||
Ubuntu 18.04 includes ocrmypdf 6.1.2. To install a more recent version, first
|
||||
install the system version to get most of the dependencies:
|
||||
Ubuntu 18.04 includes ocrmypdf 6.1.2. To install a more recent version,
|
||||
first install the system version to get most of the dependencies:
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
@@ -120,16 +132,17 @@ install the system version to get most of the dependencies:
|
||||
ocrmypdf \
|
||||
python3-pip
|
||||
|
||||
There are a few dependency changes between ocrmypdf 6.1.2 and 7.x. Let's get
|
||||
these, too.
|
||||
There are a few system dependency changes since ocrmypdf 6.1.2. Let's
|
||||
get these, too.
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
sudo apt-get install \
|
||||
libexempi3 \
|
||||
libxml2 \
|
||||
pngquant
|
||||
|
||||
Then install the most recent ocrmypdf for the local user and set the user's ``PATH`` to check for the user's Python packages.
|
||||
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
|
||||
|
||||
@@ -139,13 +152,13 @@ Then install the most recent ocrmypdf for the local user and set the user's ``PA
|
||||
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
|
||||
3.6. Ubuntu 16.04 ships Python 3.5, but you can install Python 3.6 on it. Or,
|
||||
you can skip Python 3.6 and install OCRmyPDF 7.x or older - for that procedure,
|
||||
please see the installation documentation for the version of OCRmyPDF you plan
|
||||
to use.
|
||||
No package is available for Ubuntu 16.04. OCRmyPDF 8.0 and newer require
|
||||
Python 3.6. Ubuntu 16.04 ships Python 3.5, but you can install Python
|
||||
3.6 on it. Or, you can skip Python 3.6 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**
|
||||
|
||||
@@ -167,13 +180,13 @@ to use.
|
||||
tesseract-ocr \
|
||||
unpaper
|
||||
|
||||
This will install a Python 3.6 binary at ``/usr/bin/python3.6`` 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.
|
||||
This will install a Python 3.6 binary at ``/usr/bin/python3.6``
|
||||
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 3.6. This will install the Python 3.6 version of
|
||||
``pip`` at ``/usr/local/bin/pip``.
|
||||
Now install pip for Python 3.6. This will install the Python 3.6 version
|
||||
of ``pip`` at ``/usr/local/bin/pip``.
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
@@ -181,8 +194,8 @@ Now install pip for Python 3.6. This will install the Python 3.6 version of
|
||||
|
||||
**Install OCRmyPDF**
|
||||
|
||||
OCRmyPDF requires the locale to be set for UTF-8. **On some minimal Ubuntu
|
||||
installations systems**, it may be necessary to set the locale.
|
||||
OCRmyPDF requires the locale to be set for UTF-8. **On some minimal
|
||||
Ubuntu installations systems**, it may be necessary to set the locale.
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
@@ -201,11 +214,12 @@ environment variable contains ``$HOME/.local/bin``.
|
||||
To add JBIG2 encoding, see :ref:`jbig2`.
|
||||
|
||||
Ubuntu 14.04 LTS
|
||||
^^^^^^^^^^^^^^^^
|
||||
----------------
|
||||
|
||||
Installing on Ubuntu 14.04 LTS (trusty) is more difficult than some other
|
||||
options, because of its age. Several backports are required. For explanations of
|
||||
some steps of this procedure, see the similar steps for Ubuntu 16.04.
|
||||
Installing on Ubuntu 14.04 LTS (trusty) is more difficult than some
|
||||
other options, because of its age. Several backports are required. For
|
||||
explanations of some steps of this procedure, see the similar steps for
|
||||
Ubuntu 16.04.
|
||||
|
||||
Install system dependencies:
|
||||
|
||||
@@ -222,12 +236,12 @@ Install system dependencies:
|
||||
qpdf
|
||||
|
||||
We will need backports of Ghostscript 9.16, libav-11 (for unpaper 6.1),
|
||||
Tesseract 4.00 (alpha), and Python 3.6. This will replace Ghostscript and
|
||||
Tesseract 3.x on your system. Python 3.6 will be installed alongside the system
|
||||
Python 3.4.
|
||||
Tesseract 4.00 (alpha), and Python 3.6. This will replace Ghostscript
|
||||
and Tesseract 3.x on your system. Python 3.6 will be installed alongside
|
||||
the system Python 3.4.
|
||||
|
||||
If you prefer to not modify your system in this matter, consider using a Docker
|
||||
container.
|
||||
If you prefer to not modify your system in this matter, consider using a
|
||||
Docker container.
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
@@ -253,7 +267,10 @@ Now we need to install ``pip`` and let it install ocrmypdf:
|
||||
curl https://bootstrap.pypa.io/ez_setup.py -o - | python3.6 && python3.6 -m easy_install pip
|
||||
pip3.6 install ocrmypdf
|
||||
|
||||
These installation instructions omit the optional dependency ``unpaper``, which is only available at version 0.4.2 in Ubuntu 14.04. The author could not find a backport of ``unpaper``, and created a .deb package to do the job of installing unpaper 6.1 (for x86 64-bit only):
|
||||
These installation instructions omit the optional dependency
|
||||
``unpaper``, which is only available at version 0.4.2 in Ubuntu 14.04.
|
||||
The author could not find a backport of ``unpaper``, and created a .deb
|
||||
package to do the job of installing unpaper 6.1 (for x86 64-bit only):
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
@@ -263,44 +280,52 @@ These installation instructions omit the optional dependency ``unpaper``, which
|
||||
To add JBIG2 encoding, see :ref:`jbig2`.
|
||||
|
||||
ArchLinux (AUR)
|
||||
^^^^^^^^^^^^^^^
|
||||
---------------
|
||||
|
||||
.. image:: https://repology.org/badge/version-for-repo/aur/ocrmypdf.svg
|
||||
:alt: ArchLinux
|
||||
:target: https://repology.org/metapackage/ocrmypdf
|
||||
|
||||
There is an `ArchLinux User Repository package for ocrmypdf <https://aur.archlinux.org/packages/ocrmypdf/>`_. You can use the following command.
|
||||
There is an `ArchLinux User Repository package for
|
||||
ocrmypdf <https://aur.archlinux.org/packages/ocrmypdf/>`__. You can use
|
||||
the following command.
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
yaourt -S ocrmypdf
|
||||
|
||||
If you have any difficulties with installation, check the repository package page.
|
||||
If you have any difficulties with installation, check the repository
|
||||
package page.
|
||||
|
||||
Other Linux packages
|
||||
^^^^^^^^^^^^^^^^^^^^
|
||||
--------------------
|
||||
|
||||
See the `Repology <https://repology.org/metapackage/ocrmypdf/versions>`_ page.
|
||||
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`_ to install a more recent version.
|
||||
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:
|
||||
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:
|
||||
This will include only the English language pack. If you need other
|
||||
languages you can optionally install them all:
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
@@ -308,18 +333,23 @@ This will include only the English language pack. If you need other languages yo
|
||||
|
||||
.. 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.
|
||||
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.
|
||||
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.
|
||||
|
||||
If it's not already present, `install Homebrew <http://brew.sh/>`_.
|
||||
If it's not already present, `install Homebrew <http://brew.sh/>`__.
|
||||
|
||||
Update Homebrew:
|
||||
|
||||
@@ -327,18 +357,22 @@ Update Homebrew:
|
||||
|
||||
brew update
|
||||
|
||||
Install or upgrade the required Homebrew packages, if any are missing. To do this, download the ``Brewfile`` that lists all of the dependencies to the current directory, and run ``brew bundle`` to process them (installing or upgrading as needed). ``Brewfile`` is a plain text file.
|
||||
Install or upgrade the required Homebrew packages, if any are missing.
|
||||
To do this, download the ``Brewfile`` that lists all of the dependencies
|
||||
to the current directory, and run ``brew bundle`` to process them
|
||||
(installing or upgrading as needed). ``Brewfile`` is a plain text file.
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
wget https://github.com/jbarlow83/OCRmyPDF/raw/master/.travis/Brewfile
|
||||
brew bundle
|
||||
|
||||
This will include the English, French, German and Spanish language packs. If you need other languages you can optionally install them all:
|
||||
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
|
||||
.. code-block:: bash
|
||||
|
||||
brew install tesseract --with-all-languages # Option 2: for all language packs
|
||||
|
||||
@@ -367,24 +401,28 @@ The command line program should now be available:
|
||||
ocrmypdf --help
|
||||
|
||||
Installing on FreeBSD
|
||||
---------------------
|
||||
=====================
|
||||
|
||||
FreeBSD 11.2 is known to work. Other versions likely work but have not been tested.
|
||||
FreeBSD 11.2 is known to work. Other versions likely work but have not
|
||||
been tested.
|
||||
|
||||
In general it should work to:
|
||||
|
||||
#. `Install and build pikepdf <https://pikepdf.readthedocs.io/en/latest/installation.html#installing-on-freebsd-11-2>`_.
|
||||
#. `Install and build
|
||||
pikepdf <https://pikepdf.readthedocs.io/en/latest/installation.html#installing-on-freebsd-11-2>`__.
|
||||
#. Install the equivalent list of dependencies for Linux.
|
||||
|
||||
Installing the Docker image
|
||||
---------------------------
|
||||
===========================
|
||||
|
||||
For some users, installing the Docker image will be easier than installing all of OCRmyPDF's dependencies. For Windows, it is the only option.
|
||||
For some users, installing the Docker image will be easier than
|
||||
installing all of OCRmyPDF's dependencies. For Windows, it is the only
|
||||
option.
|
||||
|
||||
See `OCRmyPDF Docker Image <docker>`_ for more information.
|
||||
See `OCRmyPDF Docker Image <docker>`__ for more information.
|
||||
|
||||
Installing on Windows
|
||||
---------------------
|
||||
=====================
|
||||
|
||||
Direct installation on Windows is not currently possible, but it works well in
|
||||
Windows Subsystem for Linux:
|
||||
@@ -422,79 +460,113 @@ You can also :ref:`Install the Docker <docker-install>` container on Windows. En
|
||||
your command prompt can run the docker "hello world" container.
|
||||
|
||||
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 instsalled.
|
||||
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 instsalled.
|
||||
|
||||
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.
|
||||
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:
|
||||
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.
|
||||
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:
|
||||
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
|
||||
|
||||
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.
|
||||
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 3.6 or newer
|
||||
- Ghostscript 9.15 or newer
|
||||
- qpdf 8.1.0 or newer
|
||||
- Tesseract 4.0.0-alpha or newer
|
||||
- Python 3.6 or newer
|
||||
- Ghostscript 9.15 or newer
|
||||
- qpdf 8.1.0 or newer
|
||||
- Tesseract 4.0.0-alpha or newer
|
||||
|
||||
As of ocrmypdf 7.2.1, the following versions are recommended:
|
||||
|
||||
- Python 3.7
|
||||
- Ghostscript 9.23 or newer
|
||||
- qpdf 8.2.1
|
||||
- Tesseract 4.0.0 or newer
|
||||
- jbig2enc 0.29 or newer
|
||||
- pngquant 2.5 or newer
|
||||
- unpaper 6.1
|
||||
- Python 3.7
|
||||
- Ghostscript 9.23 or newer
|
||||
- qpdf 8.2.1
|
||||
- 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, 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`.
|
||||
**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``.
|
||||
**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.
|
||||
**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 3.6 or newer installed, you can install from source. When the ``pip`` installer runs, it will alert you if dependencies are missing.
|
||||
If you have ``git`` and Python 3.6 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.
|
||||
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:
|
||||
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:
|
||||
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:
|
||||
You may find it easiest to install in a virtual environment, rather than
|
||||
system-wide:
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
@@ -504,8 +576,8 @@ You may find it easiest to install in a virtual environment, rather than system-
|
||||
cd OCRmyPDF
|
||||
pip3 install .
|
||||
|
||||
However, ``ocrmypdf`` will only be accessible on the system PATH
|
||||
when you activate the virtual environment.
|
||||
However, ``ocrmypdf`` will only be accessible on the system PATH when
|
||||
you activate the virtual environment.
|
||||
|
||||
To run the program:
|
||||
|
||||
@@ -519,7 +591,7 @@ 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:
|
||||
|
||||
@@ -535,15 +607,17 @@ To install all of the development and test requirements:
|
||||
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.
|
||||
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 ``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
|
||||
To manually install the ``fish`` completion, copy
|
||||
``misc/completion/ocrmypdf.fish`` to
|
||||
``~/.config/fish/completions/ocrmypdf.fish``.
|
||||
|
||||
+166
-57
@@ -1,119 +1,228 @@
|
||||
============
|
||||
Introduction
|
||||
============
|
||||
|
||||
OCRmyPDF is a Python 3 package that adds OCR layers to PDFs.
|
||||
|
||||
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 searched and copied.
|
||||
`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 searched and copied.
|
||||
|
||||
OCRmyPDF uses `Tesseract <https://github.com/tesseract-ocr/tesseract>`_, the best available open source OCR engine, to perform OCR.
|
||||
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 formats for exchanging scanned documents.
|
||||
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 formats for exchanging scanned documents.
|
||||
|
||||
.. image:: images/bitmap_vs_svg.svg
|
||||
|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 an image suitable for display or analyzing with an OCR engine. OCR engines like Tesseract work with images, not vector objects.
|
||||
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 an image suitable for
|
||||
display or analyzing with an OCR engine. OCR engines like Tesseract work
|
||||
with images, not vector objects.
|
||||
|
||||
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.
|
||||
`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.
|
||||
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.
|
||||
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 on the rasterized image to create an OCR "layer". The layer is then grafted back onto the original PDF.
|
||||
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 on 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.
|
||||
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 some image processing options like deskew which improve 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``.
|
||||
OCRmyPDF also some image processing options like deskew which improve
|
||||
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 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.).
|
||||
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.
|
||||
|
||||
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.
|
||||
|
||||
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.)
|
||||
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:
|
||||
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 solutions such as Abbyy.
|
||||
* 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.
|
||||
- The OCR is not as accurate as commercial solutions such as Abbyy.
|
||||
- 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 betweem 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.
|
||||
- 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 betweem 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.
|
||||
- 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.
|
||||
|
||||
Regarding OCRmyPDF itself:
|
||||
|
||||
* PDFs that use transparency are not currently represented in the test suite
|
||||
* The Python API exported by ``import ocrmypdf`` is design to help scripts that use OCRmyPDF but is not currently capable of running OCRmyPDF jobs due to limitations in an underlying library.
|
||||
- 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:
|
||||
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
|
||||
* pypdfocr
|
||||
* pdfbeads
|
||||
- pdf2pdfocr
|
||||
- pdfsandwich
|
||||
- pypdfocr
|
||||
- pdfbeads
|
||||
|
||||
Web front-ends
|
||||
--------------
|
||||
==============
|
||||
|
||||
The Docker image ``ocrmypdf-alpine`` 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.
|
||||
The Docker image ``ocrmypdf-alpine`` 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
|
||||
- `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.
|
||||
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
|
||||
|
||||
+34
-14
@@ -1,35 +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.
|
||||
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 not available, lower quality encodings will be used.
|
||||
JBIG2 encoding is recommended for OCRmyPDF and is used to losslessly
|
||||
create smaller PDFs. If JBIG2 encoding 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 has been part of the PDF specification since 2001.
|
||||
JBIG2 decoding is not patented and is performed automatically by most
|
||||
PDF viewers. It is widely supported 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.
|
||||
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
|
||||
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://abbyy.technology/en:kb:tip:jbig2_compression_and_ocr>`_ and decide if this feature is acceptable for their use case.
|
||||
OCRmyPDF provides lossy mode JBIG2 as an advanced feature. Users should
|
||||
`review the technical concerns with JBIG2 in lossy
|
||||
mode <https://abbyy.technology/en:kb:tip:jbig2_compression_and_ocr>`__
|
||||
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.
|
||||
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.
|
||||
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.*
|
||||
*Due to an oversight, ocrmypdf v7.0 and v7.1 used lossy mode by
|
||||
default.*
|
||||
|
||||
+24
-14
@@ -1,16 +1,20 @@
|
||||
.. _lang-packs:
|
||||
|
||||
====================================
|
||||
Installing additional language packs
|
||||
====================================
|
||||
|
||||
OCRmyPDF uses Tesseract for OCR, and relies on its language packs for languages other than English.
|
||||
OCRmyPDF uses Tesseract for OCR, and relies on its language packs for
|
||||
languages other than English.
|
||||
|
||||
Tesseract supports `most languages <https://github.com/tesseract-ocr/tesseract/blob/master/doc/tesseract.1.asc#languages>`_.
|
||||
Tesseract supports `most
|
||||
languages <https://github.com/tesseract-ocr/tesseract/blob/master/doc/tesseract.1.asc#languages>`__.
|
||||
|
||||
For Linux users, you can often find packages that provide language packs:
|
||||
For Linux users, you can often find packages that provide language
|
||||
packs:
|
||||
|
||||
Debian and Ubuntu users
|
||||
-----------------------
|
||||
=======================
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
@@ -20,11 +24,13 @@ Debian and Ubuntu users
|
||||
# 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+fre`` (English and French) or ``-l eng -l fre``.
|
||||
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+fre`` (English and French) or
|
||||
``-l eng -l fre``.
|
||||
|
||||
Fedora users
|
||||
------------
|
||||
============
|
||||
|
||||
.. code-block:: bash
|
||||
|
||||
@@ -34,16 +40,20 @@ Fedora users
|
||||
# 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+fre`` (English and French) or ``-l eng -l fre``.
|
||||
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+fre`` (English and French) or
|
||||
``-l eng -l fre``.
|
||||
|
||||
macOS users
|
||||
-----------
|
||||
===========
|
||||
|
||||
You can install additional language packs by :ref:`installing Tesseract using Homebrew with all language packs <macos-all-languages>`.
|
||||
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>`.
|
||||
Users of the OCRmyPDF Docker image should install language packs into a
|
||||
derived Docker image as
|
||||
:ref:`described in that section <docker-lang-packs>`.
|
||||
|
||||
@@ -0,0 +1,24 @@
|
||||
=======
|
||||
Plugins
|
||||
=======
|
||||
|
||||
You can use plugins to customize the behavior of OCRmyPDF at certain
|
||||
points of interest.
|
||||
|
||||
Currently, it is possible to: - override the decision for whether or not
|
||||
to perform OCR on a particular file - modify the image is about to be
|
||||
sent for OCR
|
||||
|
||||
How plugins are imported
|
||||
========================
|
||||
|
||||
Plugins are imported on demand, by the OCRmyPDF worker process that
|
||||
needs to use them. As such, plugins cannot share state with each other,
|
||||
and will be imported many times, once for each worker process.
|
||||
|
||||
Plugins currently cannot override the same hook.
|
||||
|
||||
How plugins are invoked
|
||||
=======================
|
||||
|
||||
Plugins may be called from the command line:
|
||||
+1176
-765
File diff suppressed because it is too large
Load Diff
+116
-33
@@ -1,79 +1,162 @@
|
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===================
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PDF security issues
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===================
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OCRmyPDF should only be used on PDFs you trust. It is not designed to protect you against malware.
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OCRmyPDF should only be used on PDFs you trust. It is not designed to
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protect you against malware.
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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.
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Recognizing that many users have an interest in handling PDFs and
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applying OCR to PDFs they did not generate themselves, this article
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discusses the security implications of PDFs and how users can protect
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themselves.
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The disclaimer applies: this software has no warranties of any kind.
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PDFs may contain malware
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------------------------
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========================
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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 possible attack vectors.
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PDF is a rich, complex file format. The official PDF 1.7 specification,
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ISO 32000:2008, is hundreds of pages long and references several annexes
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each of which are similar in length. PDFs can contain video, audio, XML,
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JavaScript and other programming, and forms. In some cases, they can
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open internet connections to pre-selected URLs. All of these possible
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attack vectors.
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In short, PDFs `may contain viruses <https://security.stackexchange.com/questions/64052/can-a-pdf-file-contain-a-virus>`_.
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In short, PDFs `may contain
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viruses <https://security.stackexchange.com/questions/64052/can-a-pdf-file-contain-a-virus>`__.
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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 restore searchability.
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This
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`article <https://theinvisiblethings.blogspot.ca/2013/02/converting-untrusted-pdfs-into-trusted.html>`__
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describes a high-paranoia method which allows potentially hostile PDFs
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to be viewed and rasterized safely in a disposable virtual machine. A
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trusted PDF created in this manner is converted to images and loses all
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information making it searchable and losing all compression. OCRmyPDF
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could be used restore searchability.
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How OCRmyPDF processes PDFs
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---------------------------
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===========================
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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.
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OCRmyPDF must open and interpret your PDF in order to insert an OCR
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layer. First, it runs all PDFs through
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`pikepdf <https://github.com/pikepdf/pikepdf>`__, a library based on
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`qpdf <https://github.com/qpdf/qpdf>`__, a program that repairs PDFs
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with syntax errors. This is done because, in the author's experience, a
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significant number of PDFs in the wild especially those created by
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scanners are not well-formed files. qpdf makes it more likely that
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OCRmyPDF will succeed, but offers no security guarantees. qpdf is also
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used to split the PDF into single page PDFs.
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Finally, OCRmyPDF rasterizes each page of the PDF using `Ghostscript <http://ghostscript.com/>`_ in ``-dSAFER`` mode.
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Finally, OCRmyPDF rasterizes each page of the PDF using
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`Ghostscript <http://ghostscript.com/>`__ in ``-dSAFER`` mode.
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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.
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Depending on the options specified, OCRmyPDF may graft the OCR layer
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into the existing PDF or it may essentially reconstruct ("re-fry") a
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visually identical PDF that may be quite different at the binary level.
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That said, OCRmyPDF is not a tool designed for sanitizing PDFs.
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.. _ocr-service:
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Using OCRmyPDF online or as a service
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-------------------------------------
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=====================================
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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, OCRmyPDF's GPL license, and any other licenses.
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OCRmyPDF is not designed for use as a public web service where a
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malicious user could upload a chosen PDF. In particular, it is not
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necessarily secure against PDF malware or PDFs that cause denial of
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service. OCRmyPDF relies on Ghostscript, and therefore, if deployed
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online one should be prepared to comply with Ghostscript's Affero GPL
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license, OCRmyPDF's GPL license, and any other licenses.
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Setting aside these concerns, a side effect of OCRmyPDF is it may incidentally sanitize PDFs that contain certain types of malware. It runs ``qpdf`` to repair the PDF, 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.
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Setting aside these concerns, a side effect of OCRmyPDF is it may
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incidentally sanitize PDFs that contain certain types of malware. It
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runs ``qpdf`` to repair the PDF, which could correct malformed PDF
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structures that are part of an attack. When PDF/A output is selected
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(the default), the input PDF is partially reconstructed by Ghostscript.
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When ``--force-ocr`` is used, all pages are rasterized and reconverted
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to PDF, which could remove malware in embedded images.
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OCRmyPDF should be relatively safe to use in a trusted intranet, with some considerations:
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OCRmyPDF should be relatively safe to use in a trusted intranet, with
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some considerations:
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Limiting CPU usage
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^^^^^^^^^^^^^^^^^^
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------------------
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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 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.
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OCRmyPDF will attempt to use all available CPUs and storage, so
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executing ``nice ocrmypdf`` or limiting the number of jobs with the
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``-j`` argument may ensure the server remains available. Another option
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would be run OCRmyPDF jobs inside a Docker container, a virtual machine,
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or a cloud instance, which can impose its own limits on CPU usage and be
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terminated "from orbit" if it fails to complete.
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Temporary storage requirements
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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------------------------------
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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.
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OCRmyPDF will use a large amount of temporary storage for its work,
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proportional to the total number of pixels needed to rasterize the PDF.
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The raster image of a 8.5×11" color page at 300 DPI takes 25 MB
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uncompressed; OCRmyPDF saves its intermediates as PNG, but that still
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means it requires about 9 MB per intermediate based on average
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compression ratios. Multiple intermediates per page are also required,
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depending on the command line given. A rule of thumb would be to allow
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100 MB of temporary storage per page in a file – meaning that a small
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cloud servers or small VM partitions should be provisioned with plenty
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of extra space, if say, a 500 page file might be sent.
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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.
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To check temporary storage usage on actual files, run
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``ocrmypdf -k ...`` which will preserve and print the path to temporary
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storage when the job is done.
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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>`_.
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To change where temporary files are stored, change the ``TMPDIR``
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environment variable for ocrmypdf's environment. (Python's
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``tempfile.gettempdir()`` returns the root directory in which temporary
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files will be stored.) For example, one could redirect ``TMPDIR`` to a
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large RAM disk to avoid wear on HDD/SSD and potentially improve
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performance. On Amazon Web Services, ``TMPDIR`` can be set to `empheral
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storage <https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/InstanceStorage.html>`__.
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Timeouts
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^^^^^^^^
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--------
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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.
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To prevent excessively long OCR jobs consider setting
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``--tesseract-timeout`` and/or ``--skip-big`` arguments. ``--skip-big``
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is particularly helpful if your PDFs include documents such as reports
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on standard page sizes with large images attached - often large images
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are not worth OCR'ing anyway.
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Commercial alternatives
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^^^^^^^^^^^^^^^^^^^^^^^
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-----------------------
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The author also provides professional services that include OCR and building databases around PDFs, and is happy to provide consultation.
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Abbyy Cloud OCR is a viable commercial alternative with a web services API.
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The author also provides professional services that include OCR and
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building databases around PDFs, and is happy to provide consultation.
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Abbyy Cloud OCR is a viable commercial alternative with a web services
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API.
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Password protection, digital signatures and certification
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---------------------------------------------------------
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=========================================================
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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.
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Password protected PDFs usually have two passwords, and owner and user
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password. When the user password is set to empty, PDF readers will open
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the file automatically and marked it as "(SECURED)". While not as
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reliable as a digital signature, this indicates that whoever set the
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password approved of the file at that time. When the user password is
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set, the document cannot be viewed without the password.
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Either way, OCRmyPDF does not remove passwords from PDFs and exits with an error on encountering them.
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Either way, OCRmyPDF does not remove passwords from PDFs and exits with
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an error on encountering them.
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``qpdf``, one of OCRmyPDF's dependencies, 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.
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``qpdf``, one of OCRmyPDF's dependencies, can remove passwords. If the
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owner and user password are set, a password is required for ``qpdf``. If
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only the owner password is set, then the password can be stripped, even
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if one does not have the owner password.
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After OCR is applied, password protection is not permitted on PDF/A documents but the file can be converted to regular PDF.
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After OCR is applied, password protection is not permitted on PDF/A
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documents but the file can be converted to regular PDF.
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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.
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Many programs exist which are capable of inserting an image of someone's
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signature. On its own, this offers no security guarantees. It is trivial
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to remove the signature image and apply it to other files. This practice
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offers no real security.
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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.
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Important documents can be digitally signed and certified to attest to
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their authorship. OCRmyPDF cannot do this. Open source tools such as
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pdfbox (Java) have this capability as does Adobe Acrobat.
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Reference in New Issue
Block a user