feat(lcms2-oracle): transform, ΔE, and black-point bindings plus synthesizer corpus - #358
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feat(lcms2-oracle): transform, ΔE, and black-point bindings plus synthesizer corpus#358justin13888 wants to merge 3 commits into
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Extends the dev-only Little-CMS oracle beyond profile synthesis and inspection so colour transforms can be differentially validated: - RAII Transform over cmsHTRANSFORM (pair, multiprofile, proofing) with f64/u16/u8 apply paths; TYPE_* pixel-format codes rebuilt as documented const fns (bindgen cannot expand the *_SH macro forms) and cmsFLAGS_* transcribed with lcms2.h line citations, both pinned by tests; INTENT_* re-exported from the generated bindings. - Public ToneCurve (gamma/parametric/tabulated, eval, reverse) and cmsXYZ2Lab/cmsLab2XYZ, dE76/CIEDE2000, and the v2/v4 Lab and XYZ encoders; black-point detection; quiet log handler; alarm codes. - New synthesizers for the CMM engine test corpus: scnr camera profiles (matrix-shaper + LUT), v4 and v2 CMYK prtr with distinct per-intent A2B/B2A tables, Display P3 with the true piecewise sRGB TRC (parametric type 4), v2 matrix-shaper with and without chad, and a v4 shaper with a real (non-D50) wtpt for absolute-intent tests; existing synthesizers move to synth.rs with re-exports. build.rs is byte-identical: the existing cms.* allowlists already generate every binding used here. Part of #322.
Differential suite over the new oracle bindings: CIEDE2000 agrees with cmsCIE2000DeltaE to 1e-12 across 632 seeded pairs including hue-wrap, one-chroma-zero, and achromatic edges (weighted variant included); XYZ<->Lab matches cmsXYZ2Lab/cmsLab2XYZ to 1e-12 under an explicit D50 white, with the ~3e-6 rounded-literal white divergence measured and bounded separately; the v2/v4 16-bit Lab and PCSXYZ encoders match lcms2 exactly over dense sweeps and every clamp boundary, skipping only inputs inside lcms2's documented fast-floor ambiguity window. Part of #322.
Every profile the new lcms2-oracle synthesizers emit (scnr matrix and LUT camera profiles, v4/v2 CMYK prtr, Display P3 with the piecewise sRGB TRC, v2 shapers with and without chad, the non-D50-wtpt shaper) parses without error and round-trips; the v2 prtr's A2B0 decodes as lut16 and the v4 prtr's as lutAToB, pinning the version-dependent tag serialization the CMM's per-intent selection relies on. Part of #322.
This was referenced Aug 15, 2026
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Summary
PR 2/9 of the gamut-cmm stack (epic #323), stacked on #351. Extends
tooling/lcms2-oracleso colour transforms — not just profiles — can be differentially validated against Little-CMS:TransformovercmsHTRANSFORM(profile pair, multiprofile, proofing) with f64/u16/u8 apply paths; black-point detection; quiet log handler; alarm codes; publicToneCurve(gamma/parametric/tabulated, eval, reverse);cmsXYZ2Lab/cmsLab2XYZ, ΔE76/CIEDE2000, and the v2/v4 Lab + XYZ encoders.TYPE_*/cmsFLAGS_*constants rebuilt in Rust — bindgen cannot expand the function-like*_SH()macro forms, so a documentedconst fnreplicates the packing (pinned against the verified numeric values) and the flags are transcribed withlcms2.hline citations.build.rsis byte-identical (issue acceptance criterion).scnrcamera profiles (matrix-shaper + LUT), v4 and v2 CMYKprtrwith six distinct per-intent A2B/B2A tables, Display P3 with the true piecewise sRGB TRC (parametric type 4), v2 matrix-shaper with/withoutchad, and a v4 shaper with a real non-D50wtpt(absolute-intent test vehicle —cmsCreateRGBProfilealways writeswtpt = D50+chad, which would make those tests vacuous).gamut-colorΔE₀₀ agrees withcmsCIE2000DeltaEto ≤1e-12 over 632 seeded pairs (hue-wrap/achromatic edges included); XYZ↔Lab ≤1e-12 under explicit D50; encoders match lcms2 exactly over dense sweeps + every clamp boundary (lcms2's fast-floor ambiguity window documented and skipped).gamut-iccparses and round-trips every new synthesizer profile and pins the v2→lut16/ v4→lutAToBtag serialization.Validation
cargo test -p gamut-color -p gamut-icc --all-features+ oracle's own tests: all green (15 oracle, 6 new gamut-color, 2 new gamut-icc tests).-D warnings,mise run fmt-checkclean;git diff --stat tooling/lcms2-oracle/build.rsempty.Stack
#321 (#351) → #322 (this) → #324 → #325 → #326 → #327 → #328 → #329 → #330.
Closes #322. Part of #323.