A PDF's DeviceCMYK image opened as RGB (the interpreter's pixels as a PNG),
so every export wrote it as DeviceRGB or ICC RGB, silently. Images now keep
their CMYK samples, as CMYK colours already did:
- Model: CMYK images are blobs holding CMYK samples, a four-component JPEG
(Adobe's inverted samples) or a Deflate CMYK TIFF. vectorcraft-doc's cmyk
module reads their ink amounts (ImageBlob::is_cmyk, ::cmyk, capped at 64
megapixels) and writes the TIFF (ImageBlob::cmyk_tiff).
- PDF import: DeviceCMYK, CalCMYK and four-component ICC images keep their
samples. A JPEG with Decode [1 0 1 0 1 0 1 0] is kept byte for byte; any
other is decoded (8 or 16 bits, its Decode array applied) and stored as a
CMYK TIFF. Masked CMYK images and 1/2/4-bit ones open in RGB with a warning.
Placing a CMYK TIFF keeps it CMYK too.
- PDF export: CMYK images are written in CMYK (DeviceCMYK, or ICC-based with
the CMYK profile when colours are tagged: PDF/X-3, PDF/X-4, PDF/A). A CMYK
JPEG neither resampled nor recompressed passes through unchanged; others are
resampled in CMYK and compressed as ZIP or as a CMYK JPEG (jpeg-encoder,
which also replaces the ZIP fallback and its warning for images converted to
CMYK). Output conversion treats them like CMYK colours: Preserve Numbers and
PDF/X-1a keep their numbers, Convert to Destination converts them to another
CMYK profile or to RGB through a 17^4 lookup table (cms::CmykLut, now also
behind the renderer's ink table). A CMYK image that can't be decoded is
reported in the warnings.
- Canvas: CMYK images show through the working CMYK profile, as CMYK fills
do, and paint their own inks in ink planes (CMYK raster exports, CMYK
blending). SVG export writes TIFF images as PNG.
Illustrator's Output › No Conversion keeps colour data as it is
(https://helpx.adobe.com/illustrator/using/pdf-options.html).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
document.export {format: "jpg"} takes colorModel (rgb|cmyk|gray), quality 0–100, method
(baseline|optimized|progressive), scans (3–5), embedIcc and imageMap (none|client|server).
JPEGs are written with jpeg-encoder. CMYK files hold ink amounts drawn as the renderer's ink
planes, so CMYK colours keep their inks (black type stays black ink alone). Profiles are made
in code from the CMS (cms::icc_bytes): the RGB spaces from their primaries, the CMYK spaces as
Lab lookup tables sampled from their model, a grey with sRGB's tone curve, and loaded
profiles as loaded. Image maps write <stem>.html or <stem>.map beside the image for objects
with a URL and an Image Map shape. The JPEG Options dialog gains Color Model, Quality 0–10,
Method and Scans, Image Map and Embed ICC Profile; CMYK documents default to CMYK.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Same treatment as the branch's `as_chunks` commit (Rust 1.99's
`chunks_exact_to_as_chunks` lint) for the flattener's coverage pass, the
CMYK ink compositor, the Flattener Preview highlight and four test helpers.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
A CMYK document that shows transparency is drawn once per ink plane
(complemented C, M, Y; complemented K as a grey) so every blend mode,
opacity, group, knockout and effect composites inks, PDF-style; the
planes' inks are shown through the working CMYK profile (cached 4-D XYZ
table). Cyan multiplied over magenta now shows C100 M100. Opacity masks
keep screen luminance; RGB colours and placed images are separated
first. RGB documents and opaque CMYK documents keep the screen-colour
path.
PDF export of CMYK documents writes its transparency groups with
/CS /DeviceCMYK (luminosity mask groups stay RGB) and puts top-level
transparency in a non-isolated page-wide group so it blends in CMYK too.
Flatten Transparency composites CMYK documents ink by ink and makes CMYK
regions. Non-separable modes no longer give NaN for greys.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
