Grzegorz MartensandClaude Opus 5.5 39eb03a0b6 M11: Monochrome Images reads JBIG2 scans: averaged like any, and stored again as JBIG2 ...

#5461 made Document::decoded_image read JBIG2, page exactly the image's size, and
kept the optimizer's monochrome step off it until it could weigh JBIG2 again. Now
one_bit reads JBIG2 last after any filters, within the raster's allowance, and mono
treats it as it does any black-and-white image:
- above the threshold it is averaged, and stored as the compression asks, the
  smallest of what that may store; under Retain it is stored as JBIG2 again, its kind
  of compression kept;
- not resampled, it is stored again as the compression asks when that is smaller: a
  generic region becomes symbols with JBIG2 asked for, and JBIG2 behind ASCIIHex is
  stored again alone (as Group 4 where that is smaller);
- a JBIG2 image stored again refers to no /JBIG2Globals; one whose page isn't its
  size isn't read, and stays.

jbig2_images_are_left_as_they_are becomes jbig2_scans_are_averaged_and_stored_again:
a JBIG2 scan at 600 ppi, alone, behind ASCIIHex and with globals, averages to the
same samples as its Flate copy under each compression (Retain keeping JBIG2); at 300
ppi a generic region of rendered text stays under Group 4 (larger) and Retain and
becomes symbols under JBIG2 (under half the size); behind ASCIIHex it is stored again
alone, as Group 4 where the hex is spaced out; a taller page stays.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

2026-10-30 19:05:09 +01:00

..

jpeg_color_transform.rs

style: rustfmt the cancellation test

2026-10-23 10:53:16 +02:00

optimize.rs

M11: Monochrome Images reads JBIG2 scans: averaged like any, and stored again as JBIG2

2026-10-30 19:05:09 +01:00