Grzegorz MartensandClaude Opus 5.5
907a9fa917
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
pdfcraft-create
Layer L4. Create a PDF (Acrobat's Create a PDF tool), execution plan M10.2:
blank(width, height, pages): an empty document;from_images(&[(name, bytes)]): one page per image, sized from the image's resolution (PNGpHYs, JPEG JFIF density; 72 dpi when absent). JPEG data is embedded as is (/DCTDecode, grey, RGB or Adobe-inverted CMYK); PNG is decoded and stored with Flate, with transparency as a soft mask. A picture of only pure black and white (a 1-bit PNG or TIFF, eight-bit grey, a two-colour palette, RGB without a profile) is stored at one bit per pixel, as CCITT Group 4 or Flate, whichever is smaller as stored (pdfcraft_filters::encode_g4). Redaction doesn't decode Group 4 yet: a mark over part of such a picture removes the whole picture (nothing leaks). An ICC profile in the file (JPEGAPP2 ICC_PROFILE, PNGiCCP) that matches the image's colour space is kept as an/ICCBasedcolour space with the device space as/Alternate; images with the same profile share one profile object. JPEG metadata scanning skips marker fill bytes and reads application segments after the frame header, stopping at the first scan or end marker. Broken or mismatched ICC profiles still fall back to the device colour space;from_images_with_resolution(images, ImageResolution::Dpi(dpi)): override the page resolution (1–1200 dpi), without resampling or recompressing image pixels. Use 72 dpi for one point per pixel, orImageResolution::Embeddedfor the same behavior asfrom_images. The largest page side is still capped at 14,400 points;from_text(text, …): plain text set in Helvetica, wrapped and paginated. Text Helvetica can't draw is refused, naming the line and the character, never set as?.from_text_escaped(text, …): the same for reports PdfCraft generates from documents (comment summaries, compare reports): such characters are written as[U+XXXX]and the first line says so (ESCAPED_NOTE).
Every function returns a pdfcraft_cos::Document; the caller writes it.
Image export and Save Image As apply each lossless image's Decode pair before converting its color components.
Indexed Decode values select palette entries after rounding and clipping. Color-key masks compare the original samples.
Missing, null or malformed Decode arrays keep the default mapping.
Soft-mask Decode intervals map samples to opacity before the mask is resized, including reversed ranges and indirect entries.
The existing 16-bit path still uses each sample's high byte.
JPEG image Decode handling remains limited.
ICC transforms and calibrated color conversion remain outside this export path.
CCITT fax images (Group 3 and 4) are decoded for export through pdfcraft_cos::Document::decoded_image with their
/DecodeParms (/Columns has to be the image's width; up to /Height rows, whatever /Rows says), behind other filters such as
ASCII85Decode too. Byte-aligned Group 3 rows are read by their end-of-line codes, whether the fill starts each code on a byte or
ends it on one, when the data starts with one (T.4 sends one before the first row), and on bytes otherwise, whatever /EndOfLine
says; data that comes up short is reported. Data with codes but none before the first row is read on bytes, and is reported or,
at /K 0, may come out wrong. JPEG 2000 and JBIG2 images are still reported, not exported.