The PDF Optimizer and Reduce File Size downsampled colour and grey images
but not black-and-white ones. Settings::mono is now MonoSettings {
downsample, target_ppi, above_ppi, compression }, 300 ppi above 450 ppi
and CCITT Group 4 by default (Monochrome Images ▸ Downsample to;
doc_optimize mono: { downsample, ppi, above_ppi, compression }).
A 1-bit image or image mask (no filter, general-purpose filters, or CCITT
fax after any of them) and eight-bit grey of only black and white are averaged by
area: each new pixel takes the sample covering more of it, a tie 0, so a
dark line half a new pixel wide stays. They are stored as Group 4, or as
1-bit Flate when that is smaller; with Retain a resampled image keeps its
kind of compression. Images with a soft mask keep their size.
CCITT decoding moves from Export ▸ Images into pdfcraft-filters
(decode_ccitt, CcittParams, through hayro-ccitt), and
pdfcraft_cos::Document::decoded_image reads a fax image's /DecodeParms
for it (undoing filters before CCITT, such as ASCII85Decode, with any
/DecodeParms given by reference made direct first), so export
and the optimizer share one reader, and Group 4 scans can be
downsampled. A 600 ppi text page went from 79 KB to 40 KB.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BfMGHQNgdq5yf5tKZHGR3z
ROADMAP.md: kept both progress lines.
crates/optimize/README.md: PR's decoder sentence plus the target-version section from main.
Cargo.lock: auto-merged.
Optimize decoded DCT images with the generic JPEG decoder, which converts
three components from YCbCr to RGB whenever the JPEG itself doesn't say
otherwise, and then dropped /DecodeParms. An RGB JPEG stored untransformed
(/ColorTransform 0 and no Adobe marker) therefore came out in other colours
when recompressed, resampled or merged from strips.
The samples are now read with the colour transform ISO 32000-2 §7.4.8
gives them: an Adobe APP14 marker's flag, else /ColorTransform (default 1).
Untransformed samples are taken as stored, and the result is written as a
plain YCbCr JPEG (or Flate), which needs no /DecodeParms. When the marker
and /ColorTransform disagree, a value is out of range, the parameters are
not paired with the filter as §7.4 pairs them, or the decoder reads the
components otherwise (named R, G and B), the image is left as it is.
The tests draw each image with PdfCraft's renderer before and after
Optimize: RGB JPEGs with and without an Adobe marker under each
/ColorTransform, CMYK JPEGs (still left alone) and JPEG strips merged into
one picture.
Part of #1201.
The app, crates, binaries, bundle id, packaging, icons, screenshots and docs are now
PdfCraft / pdfcraft (repo storytold/pdfcraft). On first launch the desktop app moves the
PrintCraft settings and crash-recovery folders to the new name, and both apps read settings
saved under the old storage key, so upgrades keep recent files, preferences and unsaved work.
The signing test fixtures keep their PrintCraft subject names (they are binary).
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
