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[LTX-2.5] SDR-To-HDR in LTX2HDRPipeline (fix branch, not to be merged) - #7
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christopher5106 wants to merge 2 commits into
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christopher5106 wants to merge 2 commits into
christopher5106 wants to merge 2 commits into
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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>
Run the Lightricks LTX-2.5 SDR-To-HDR IC-LoRA (ltx_pipelines.hdr_ic_lora.HDRICLoraPipeline, without its optional seam keyframes) when the pipeline is built with hdr_transform="acescct": - the reference video goes through the ACEScct input transform (new `input_colorspace`, default "srgb_gamma"), is reflect-padded up to a multiple of the VAE spatial compression ratio and VAE-encoded in float32; the decoded video is cropped back to height x width; - conditioning comes from precomputed `connector_video_embeds` only (a 2D `video_context` is accepted): no prompt, no text encoder call, `connector_audio_embeds` optional; - video-only denoising: `isolate_modalities=True` with a single placeholder audio token, so the audio stream cannot reach the video; - the distilled schedule used verbatim (DISTILLED_SIGMA_VALUES, no mu shift), no CFG/STG/modality guidance, RoPE frame rate capped at 30 fps, first target latent frame marked for the keyframe position embedding; - decoding in float32 with the optional `diffusion_decoder` component (LTX-2.5) or the VAE, then `postprocess_hdr_video(output_colorspace=...)` (new argument, default "rec709"). `hdr_transform` is now registered in the pipeline config so it survives save/load. The LogC3 (LTX-2.3) path is unchanged: its outputs are bit-identical to the parent commit. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Tracking PR for
fix_ltx2_hdr_sdr_to_hdr, opened againstmain(the upstream mirror). It is never merged here.Upstream PR: huggingface#14974, stacked on huggingface#14966 (tracked in #5).
Adds the LTX-2.5 SDR-To-HDR IC-LoRA path to
LTX2HDRPipeline(hdr_transform="acescct"): ACEScct input, reflect pad and crop, fp32 VAE, video-onlyvideo_contextconditioning, audio isolation, distilled schedule, RoPE fps cap, optionaldiffusion_decoder. Matches Lightricks' reference on real weights: final latent 50 dB, output 38.4 dB. Tests:tests/pipelines/ltx2/test_ltx2_hdr_sdr_to_hdr.py(30).When upstream merges it: delete this branch, close this PR, sync
main, and rebasescenarioto drop the cherry-pick.