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From: "James R. Barlow" <james@purplerock.ca>
Date: Sun, 9 Nov 2025 15:43:36 -0800
Subject: [PATCH] Work around Ghostscript 10.6.0 JPEG encoding issue by forcing
optimization.
Not an ideal fix, but it improves an issue affecting numerous users.
Fixes 1585.
Obtained from:
https://github.com/ocrmypdf/OCRmyPDF/commit/f4c6c8121ba8178ff3a1cb8f70037bbc3a31391b.patch
--- src/ocrmypdf/optimize.py.orig 2020-02-02 00:00:00 UTC
+++ src/ocrmypdf/optimize.py
@@ -17,6 +17,7 @@ import img2pdf
from zlib import compress
import img2pdf
+from packaging.version import Version
from pikepdf import (
Dictionary,
Name,
@@ -32,7 +33,7 @@ from ocrmypdf._concurrent import Executor, SerialExecu
from PIL import Image
from ocrmypdf._concurrent import Executor, SerialExecutor
-from ocrmypdf._exec import jbig2enc, pngquant
+from ocrmypdf._exec import ghostscript, jbig2enc, pngquant
from ocrmypdf._jobcontext import PdfContext
from ocrmypdf._progressbar import ProgressBar
from ocrmypdf.exceptions import OutputFileAccessError
@@ -189,6 +190,16 @@ def extract_image_jbig2(
return None
+def _should_optimize_jpeg(options, filtdp):
+ if options.optimize >= 2:
+ return True
+ if options.optimize < 2 and ghostscript.version() >= Version('10.6.0'):
+ # Ghostscript 10.6.0+ introduced some sort of JPEG encoding issue.
+ # To resolve this, re-optimize the JPEG anyway.
+ return True
+ return False
+
+
def extract_image_generic(
*, pdf: Pdf, root: Path, image: Stream, xref: Xref, options
) -> XrefExt | None:
@@ -202,15 +213,7 @@ def extract_image_generic(
if pim.bits_per_component == 1:
return None
- if filtdp[0] == Name.DCTDecode and options.optimize >= 2:
- # This is a simple heuristic derived from some training data, that has
- # about a 70% chance of guessing whether the JPEG is high quality,
- # and possibly recompressible, or not. The number itself doesn't mean
- # anything.
- # bytes_per_pixel = int(raw_jpeg.Length) / (w * h)
- # jpeg_quality_estimate = 117.0 * (bytes_per_pixel ** 0.213)
- # if jpeg_quality_estimate < 65:
- # return None
+ if filtdp[0] == Name.DCTDecode and _should_optimize_jpeg(options, filtdp):
try:
imgname = root / f'{xref:08d}'
with imgname.open('wb') as f:
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