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[LTX-2.5] ACEScct colour transforms + HLG/EXR export (fix branch, not to be merged) - #5
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…-HDR Port the colour pipeline of the LTX-2.5 SDR-To-HDR IC-LoRA from the Lightricks LTX-2 reference (ltx_core.hdr, ltx_core.color, ltx_pipelines media_io): - image_processor: sRGB EOTF, Bradford Rec.709/AP1/Rec.2020 matrices, ACEScct encode/decode, the srgb_gamma/srgb/acescg/acescct input transforms and the ACEScct -> ACEScg/Rec.709 linear output transform, as pure torch functions. LTX2VideoHDRProcessor gains hdr_transform="acescct" with input_colorspace / output_colorspace options; the LogC3 default is unchanged. - export_utils: encode_hdr_tensor_to_hlg_mp4 (BT.2020 HLG 10-bit HEVC via PyAV/libx265) and save_exr_frame / export_to_exr_sequence (half-float ZIP EXR with chromaticities and colorSpace), behind a new optional is_openexr_available() guard. - tests: exact values computed with colour-science, round trips, HLG stream properties and EXR read-back. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Tracking PR for
fix_ltx2_hdr_acescct_export, opened againstmain(the upstream mirror). It is never merged here. The commit is cherry-picked ontoscenariowhile upstream reviews it.Upstream PR: huggingface#14966
Adds ACEScct colour transforms (the LTX-2.5 SDR-To-HDR IC-LoRA's colour space) and an
"acescct"mode toLTX2VideoHDRProcessor, plus an HLG BT.2020 10-bit HEVC writer and a half-float EXR writer behind an optionalOpenEXRdependency. Checked against Lightricks' reference: transforms bit-identical, HLG bitstream byte-identical, EXR pixels identical. Tests:tests/pipelines/ltx2/test_ltx2_hdr_color.py(40).This is the first of three PRs. The next two add SDR-To-HDR support to
LTX2HDRPipeline, then seam keyframes and keyframe-aware decoding.When upstream merges it: delete this branch, close this PR, sync
main, and rebasescenariodropping the cherry-pick.