James R. Barlow 11de13ecfe feat: anti-alias Ghostscript rasterization to improve OCR quality ...

Ghostscript 10.x renders aliased glyphs that OCR frequently misreads as
extra word breaks or substituted characters. Enable text and graphics
anti-aliasing (-dTextAlphaBits=4 -dGraphicsAlphaBits=4) for the contone
raster devices, which empirically improves OCR accuracy on the
Ghostscript path, especially for small fonts at moderate DPI. The 1-bit
mono devices are excluded, since older Ghostscript rejects alpha bits on
them and pngmonod performs its own anti-aliased downscaling.

Also log which rasterizer rendered each page at debug verbosity and
clarify the --rasterizer help text, so quality reports are easier to
diagnose. The default rasterizer (auto) already prefers pypdfium2, which
anti-aliases; this primarily benefits --rasterizer ghostscript and
installs without pypdfium2.

Closes #1439.

2026-06-10 23:39:03 -07:00

..

__init__.py

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concurrency.py

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default_filters.py

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ghostscript.py

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null_ocr.py

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optimize.py

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pypdfium.py

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tesseract_ocr.py

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