menekis/OCRmyPDF
Public Access
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

As you were

Browse Source
This commit is contained in:
James R. Barlow
2023-04-13 23:27:58 -07:00
parent b432770cfc
commit 01dc8e23ff
4 changed files with 200 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/ocrmypdf/pluginspec.py
+17 -10
View File
@@ -228,19 +228,26 @@ def filter_ocr_image(page: PageContext, image: Image.Image) -> Image.Image:
"""Called to filter the image before it is sent to OCR.
This is the image that OCR sees, not what the user sees when they view the
PDF. If ``redo_ocr`` is enabled, portions of the image will be masked so
they are not shown to OCR. The main use of this hook is expected to be hiding
content from OCR.
PDF. In certain modes such as ``--redo-ocr``, portions of the image may be
masked out to hide them from OCR.
The main uses of this hook are expected to be hiding content from OCR,
conditioning images to OCR better with filters, and adjusting images to
match any constraints imposed by the OCR engine.
The input image may be color, grayscale, or monochrome, and the
output image may differ. The pixel width and height of the
output image must be identical to the input image, or misalignment between
the OCR text layer and visual position of the text will occur. Likewise,
the output must be a faithful representation of the input, or alignment
errors may occurs.
output image may differ. For example, if you know that a custom OCR engine
does not care about the color of the text, you could convert the image to
it to grayscale or monochrome.
Tesseract OCR only deals with monochrome images, and internally converts
non-monochrome images to OCR.
Generally speaking, the output image should be a faithful representation of
of the input image. You *may* change the pixel width and height of the
the input image, but you must not change the aspect ratio, and you must
calculate the DPI of the output image based on the new pixel width and
height or the OCR text layer will be misaligned with the visual position.
The built-in Tesseract OCR engine uses this hook itself to downsample
very large images to fit its constraints.
Note:
This hook will be called from child processes. Modifying global state