feat(jpeg)!: migrate JPEG to gamut-jpeg; delete jpegli stack and img-parts - #52
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…parts JPEG decode moves from zune-jpeg to gamut_jpeg::JpegDecoder (baseline + progressive). Four-component streams route through gamut's Cmyk8 surface into a CMYK->RGB conversion verified bit-exact against the old zune backend; grayscale/YCbCr go through Rgb8; 16-bit scaling unchanged. probe_jpeg uses gamut's header-only info(), keeping the hand-rolled SOF scan solely for featureless builds where probing is documented to work. JPEG encode collapses jpeg-encoder AND the entire vendored jpegli stack onto gamut-jpeg: one JpegEncodeConfig with exactly gamut's knobs (quality, subsampling, progressive, restart interval, density); EncodeOptions::JpegJpegEnc/JpegJpegli collapse to Jpeg; codec id jpeg/gamut. Deleted: codecs/jpegli.rs + C++ shim, the build.rs jpegli slice (build.rs retains only cfg-alias machinery), the third_party/jpegli submodule and with it .gitmodules, deps zune-jpeg/jpeg-encoder, all four build-dependencies (bindgen/pkg-config/cc/cmake at the crate level), the jpeg backend features, and EncodeError::Jpeg/Jpegli. APP-segment metadata rides gamut both ways: extraction via gamut_jpeg::metadata() — which now also surfaces ICC and XMP into ImageMetadata where the old path read EXIF only — and embedding via the encoder's with_exif/with_icc_profile/with_xmp. That retired the last three img-parts consumers, so img-parts and the container-embed feature are fully deleted (audit: WebP muxes via its own libwebp RIFF path and never used it; AVIF splices in-crate; PNG/JXL embed via gamut encoders). Quality baseline vs the old backends (q90 re-encode of the three root fixtures): at the apples-to-apples 4:4:4 setting gamut matches the old output within ~1% size at comparable PSNR; gamut's 4:2:0 default trades ~35% smaller files. jpegli perceptual parity remains upstream (gamut#19/#29/#30). Known regressions documented on the config: quality 0 no longer remaps to 90, default subsampling is 4:2:0, and the old decoder's max-dimension DoS-guard knobs have no gamut equivalent yet (upstream ask filed; decode is also currently slower than zune — perf issue filed). BREAKING CHANGE: JPEG config/variant/codec-id renames; ExifContainer::Jpeg removed; container-embed feature and img-parts gone; jpegli vendored toolchain gone.
This was referenced Jul 18, 2026
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Closes #31.
Stacked on #51; merge order #42 → … → #51 → this. This was the last v1 hard-blocker migration (gamut#28 landed upstream 2026-07-17).
What is Delivered
Cmyk8surface into a CMYK→RGB conversion verified bit-exact against the old zune backend's formula; grayscale/YCbCr viaRgb8; probe via gamut's header-onlyinfo().JpegEncodeConfig(quality/subsampling/progressive/restart/density — exactly gamut's knobs);EncodeOptions::Jpeg; codec idjpeg/gamut. Deleted:codecs/jpegli.rs+ C++ shim, the build.rs jpegli slice, thethird_party/jpeglisubmodule (and with it.gitmodules),zune-jpeg/jpeg-encoderdeps, all four crate build-dependencies (bindgen/pkg-config/cc/cmake), and the CI submodule-checkout step.gamut_jpeg::metadata()(now surfacing ICC + XMP where the old path read EXIF only), embedding via encoder setters. That retired the last three img-parts consumers: img-parts and thecontainer-embedfeature are fully deleted (audited: WebP never used it; AVIF splices in-crate; PNG/JXL ride gamut encoders).test_jpeg_metadata_roundtrippins EXIF+ICC+XMP encode→extract.Quality baseline (issue requirement; q90 re-encode of the three root fixtures)
At the apples-to-apples 4:4:4 setting gamut matches the old backend within ~1 % output size at comparable PSNR; gamut's 4:2:0 default trades ~35 % smaller files. Full table in the work log. jpegli perceptual parity remains upstream (gamut#19/#29/#30).
Honest regressions, documented on the config
quality: 0no longer remaps to 90; default subsampling is now 4:2:0; the old decoder's max-dimension DoS-guard knobs have no gamut equivalent; gamut decode is currently slower than zune. The latter two are filed upstream (see follow-up issues).Verification Done
Run independently after implementation:
cargo test --workspace384/0;--features full541/0 (fixture suite 22/22 on the gamut path); serde config passes; clippy workspace + full-D warnings0+0;--no-default-features --features jpegstandalone clean; greps confirm zune-jpeg (direct), jpeg-encoder, img-parts, jpegli, and.gitmodulesare gone from tree, manifests, and lockfile. lefthook green.