Add CICP and HDR support #4818
Add CICP and HDR support #4818
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Great! JXL also has CICP, so that would be a good one to add. I bumped master to 8.19 ready for this to be merged when it's done. |
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CICP is now its own "colourspace" and transformations always go via scRGB. So "copy" from a CICP-tagged file should now yield somewhat decent colours. The libheif saver now also has support for CICP/nclx values. PNG saver should be relatively straightforward. Formats other than HEIF/AVIF/PNG/JXL could also profit from this, but there we'd need to generate an ICC profile with the "cicp" tag. That ICC profile should only be used for final output as lcms2 wouldn't support any transformations with it. So far conversion to CICP is not implemented. |
This is a first go at code for converting image with nclx/CICP signals to scRGB. It's incomplete and was only briefly tested for my use case: HDR AVIF with PQ transfer and Display P3 primaries.
It seems to work reasonably well so far and the output JPG and PNG look much better than using copy.
Specifically the ultrahdr output in the JPG looks pretty good if the gainmap is shown.
pics.zip
In the zip you can find the original AVIF, the non-CICP-aware out_copy.jpg, and the CICP2scRGB outputs (both PNG and JPG, but original PNG was too large).
TODO: