Grzegorz MartensandClaude Opus 5.5 e5d7184558 M11: Optimize stores a picture's one-bit masks as monochrome images ...

The image pass visits the images pages draw by name. A picture's stencil
`/Mask` and its `/SMask` are images of their own that pages don't name, so
the monochrome step never reached them (the colour and grey settings
resample an eight-bit soft mask with its picture, but store no mask as
Group 4 or JBIG2). In a mixed-raster scan, a colour layer drawn through a
one-bit mask that holds the text, most of the black-and-white data stayed
as it was written (Flate, say).

After the pictures, each picture's stencil mask and one-bit soft mask, once
however many pictures name it, now goes through the monochrome step at its
size (`decide_mask`): stored again as the compression asks (Group 4, JBIG2)
when that is smaller, its bits as they were, so it masks as it did. It
isn't resampled (its resolution isn't measured) and shares no JBIG2
dictionary (only images named directly do, which redaction can store again).
A stencil pages also draw by name stays one of the pictures; a soft mask they
draw is still stored as a mask. A soft mask of
more bits stays, to be resampled with its picture, which wants it at eight.
The report counts masks as images; Retain leaves them as they are.

The pictures and the masks go through one loop (`work_through`), so masks
are worked out on threads and from the run's allowance as pictures are.

Tests: `a_pictures_one_bit_masks_are_stored_again`,
`a_pictures_mask_stored_as_jbig2_shares_no_dictionary` and, through
`doc_optimize`, `doc_optimize_stores_a_pictures_one_bit_soft_mask_as_ccitt_group_4`.
`a_mask_past_the_runs_allowance_stays_and_is_counted` holds a mask past
the run's allowance to staying, counted as refused, and the progress to
counting masks with pictures.
`a_picture_with_a_stencil_mask_is_downsampled_under_its_mask` now checks
the mask's size and bits rather than its bytes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AmsdeUCdTaD72jkDw2pJKY

2026-11-10 09:23:57 +01:00

..

hostile.rs

fix(optimize): downsampling never enlarges; a huge target_ppi aborted on a 20 TB allocation (#5425)

2026-11-09 10:05:33 +08:00

jpeg_color_transform.rs

perf(optimize): work out pictures on threads and skip needless page reads (#6230)

2026-11-09 08:53:27 +08:00

optimize.rs

M11: Optimize stores a picture's one-bit masks as monochrome images

2026-11-10 09:23:57 +01:00