v16.4.2 release notes

Ghostscript now expects the pdfa.ps file to precede other files. Fixes #1359.

docs/advanced.rst

@@ -228,6 +228,59 @@ then run ocrmypdf as follows (along with any other desired arguments):
    Some combinations of control parameters will break Tesseract or break
    assumptions that OCRmyPDF makes about Tesseract's output.
 
+Changing page segmentation mode
+-------------------------------
+
+The directive ``--tesseract-pagesegmode Nmode`` forwards the desired page segmentation
+mode to Tesseract OCR. The default is 3.
+
+Page segmentation can improve OCR results when you know that a PDF ought to be
+analyzed a particular way, such as PDFs whose pages contain only a single line of 
+text. For the vast majority of users, changing the page segmentation mode will only
+make things worse.
+
+As of June 2024, the Tesseract page segmentation modes are:
+
++-----+----------------------------------------------------------------------------------+
+| ID  | Description                                                                      |
++=====+==================================================================================+
+|  0  | Orientation and script detection (OSD) only.                                      |
++-----+----------------------------------------------------------------------------------+
+|  1  | Automatic page segmentation with OSD.                                             |
++-----+----------------------------------------------------------------------------------+
+|  2  | Automatic page segmentation, but no OSD, or OCR. (not implemented)               |
++-----+----------------------------------------------------------------------------------+
+|  3  | Fully automatic page segmentation, but no OSD. (Default)                         |
++-----+----------------------------------------------------------------------------------+
+|  4  | Assume a single column of text of variable sizes.                                 |
++-----+----------------------------------------------------------------------------------+
+|  5  | Assume a single uniform block of vertically aligned text.                         |
++-----+----------------------------------------------------------------------------------+
+|  6  | Assume a single uniform block of text.                                            |
++-----+----------------------------------------------------------------------------------+
+|  7  | Treat the image as a single text line.                                            |
++-----+----------------------------------------------------------------------------------+
+|  8  | Treat the image as a single word.                                                 |
++-----+----------------------------------------------------------------------------------+
+|  9  | Treat the image as a single word in a circle.                                     |
++-----+----------------------------------------------------------------------------------+
+| 10  | Treat the image as a single character.                                            |
++-----+----------------------------------------------------------------------------------+
+| 11  | Sparse text. Find as much text as possible in no particular order.                |
++-----+----------------------------------------------------------------------------------+
+| 12  | Sparse text with OSD.                                                            |
++-----+----------------------------------------------------------------------------------+
+| 13  | Raw line. Treat the image as a single text line, bypassing hacks that are        |
+|     | Tesseract-specific.                                                               |
++-----+----------------------------------------------------------------------------------+
+
+Modes 0, 1, 2, and 12 (all of those that enable orientation and script detection) 
+are not compatible with OCRmyPDF, which performs OSD in a separate step from OCR.
+Their use may interfere with ``--rotate-pages`` and other features.
+
+It is currently not possible to use advanced Tesseract OCR features, such as creating
+OCR information, when using Tesseract through OCRmyPDF.
+
 Changing the PDF renderer
 =========================
 

docs/installation.rst

@@ -224,7 +224,7 @@ standard tooling needed to build packages, such as a compiler and binary tools.
 
 .. code-block:: bash
 
-   sudo pacman -S base-devel
+   sudo pacman -S --needed base-devel
 
 Now you are ready to install the OCRmyPDF package.
 
@@ -681,7 +681,7 @@ To install all of the development and test requirements:
 .. code-block:: bash
 
     git clone -b main https://github.com/ocrmypdf/OCRmyPDF.git
-    python -m .venv
+    python -m venv .venv
     source .venv/bin/activate
     cd OCRmyPDF
     pip install -e .[test]

docs/release_notes.rst

@@ -30,6 +30,26 @@ OCRmyPDF typically supports the three most recent Python versions.
 
 .. |OCRmyPDF PyPI| image:: https://img.shields.io/pypi/v/ocrmypdf.svg
 
+v16.4.2
+=======
+
+-  Fixed order of filenames passed to Ghostscript for PDF/A generation. :issue:`1359`
+-  Suppressed missing jbig2dec warning message. :issue:`1358`
+-  Fixed calculation of image size when soft mask dimensions don't match image
+   dimension. :issue:`1351`
+-  Several fixes to documentation. Thanks to users Iris and JoKalliauer
+   who contributed these changes.
+-  Fixed error on processing PDFs that are missing certain image metadata. :issue:`1315`
+
+v16.4.1
+=======
+
+-  Fixed calculation of image printed area (used in finding weighted DPI for OCR).
+   :issue:`1334`
+-  Fixed "NotImplementedError: not sure how to get colorspace" error
+   messages in logs which simply records a failure to optimize images with
+   print production colorspaces. :issue:`1315`
+
 v16.4.0
 =======
 

src/ocrmypdf/_pipeline.py

@@ -475,7 +475,7 @@ def calculate_raster_dpi(page_context: PageContext):
     page_dpi = get_page_square_dpi(page_context, image_dpi)
     if dpi_profile and dpi_profile.average_to_max_dpi_ratio < 0.8:
         log.warning(
-            "Weight average image DPI is %0.1f, max DPI is %0.1f. "
+            "Weighted average image DPI is %0.1f, max DPI is %0.1f. "
             "The discrepancy may indicate a high detail region on this page, "
             "but could also indicate a problem with the input PDF file. "
             "Page image will be rendered at %0.1f DPI.",

src/ocrmypdf/builtin_plugins/ghostscript.py

@@ -129,7 +129,7 @@ def generate_pdfa(
 ):
     """Generate a PDF/A from the list of PDF pages and PDF/A metadata."""
     ghostscript.generate_pdfa(
-        pdf_pages=[*pdf_pages, pdfmark],
+        pdf_pages=[pdfmark, *pdf_pages],
         output_file=output_file,
         compression=context.options.pdfa_image_compression,
         color_conversion_strategy=context.options.color_conversion_strategy,

src/ocrmypdf/helpers.py

@@ -268,7 +268,9 @@ def check_pdf(input_file: Path) -> bool:
         return False
     else:
         with pdf:
-            messages = pdf.check()
+            with warnings.catch_warnings():
+                warnings.filterwarnings('ignore', message=r'pikepdf.*JBIG2.*')
+                messages = pdf.check()
             success = True
             for msg in messages:
                 if 'error' in msg.lower():

src/ocrmypdf/optimize.py

@@ -28,6 +28,7 @@ from pikepdf import (
     Stream,
     UnsupportedImageTypeError,
 )
+from pikepdf.models.image import HifiPrintImageNotTranscodableError
 from PIL import Image
 
 from ocrmypdf._concurrent import Executor, SerialExecutor
@@ -200,7 +201,7 @@ def extract_image_generic(
             with imgname.open('wb') as f:
                 ext = pim.extract_to(stream=f)
             imgname.rename(imgname.with_suffix(ext))
-        except UnsupportedImageTypeError:
+        except (UnsupportedImageTypeError, HifiPrintImageNotTranscodableError):
             return None
         return XrefExt(xref, ext)
     elif (

src/ocrmypdf/pdfinfo/info.py

@@ -369,8 +369,18 @@ class ImageInfo:
             pim = PdfImage(pdfimage)
         else:
             raise ValueError("Either pdfimage or inline must be set")
-        self._width = pim.width
-        self._height = pim.height
+        if pim.obj.get(Name.SMask, None) is not None:
+            # SMask is pretty much an alpha channel, but in PDF it's possible
+            # for channel to have different dimensions than the image
+            # itself. Some PDF writers use this to create a grayscale stencil
+            # mask. For our purposes, the effective size is the size of the
+            # larger component (image or smask).
+            smask = pim.obj[Name.SMask]
+            self._width = max(smask.get(Name.Width, 0), pim.width)
+            self._height = max(smask.get(Name.Height, 0), pim.height)
+        else:
+            self._width = pim.width
+            self._height = pim.height
 
         # If /ImageMask is true, then this image is a stencil mask
         # (Images that draw with this stencil mask will have a reference to
@@ -491,7 +501,7 @@ class ImageInfo:
         """Physical area of the image in square inches."""
         if not self.renderable:
             return 0.0
-        return float(self.width * self.dpi.x * self.height * self.dpi.y)
+        return float((self.width / self.dpi.x) * (self.height / self.dpi.y))
 
     def __repr__(self):
         """Return a string representation of the image."""
@@ -573,7 +583,7 @@ def _find_form_xobject_images(pdf: Pdf, container: Object, contentsinfo: Content
     xobjs = resources[Name.XObject].as_dict()
     for xobj in xobjs:
         candidate = xobjs[xobj]
-        if candidate is None or candidate[Name.Subtype] != Name.Form:
+        if candidate is None or candidate.get(Name.Subtype) != Name.Form:
             continue
 
         form_xobject = candidate
@@ -1071,7 +1081,6 @@ class PageInfo:
 
         arg_max_dpi = image_dpis.index(max_dpi)
         max_area_ratio = image_areas[arg_max_dpi] / total_drawn_area
-
         return PageResolutionProfile(
             weighted_dpi,
             max_dpi,