6.1 HDR development thread

Develop Artists Feedback & Testing
19

Hey all,

small update, some work got done:

  1. We now support cicp tags inside icc profiles. This allows us to have separate profiles for different luminances, as well as non-rec 2100 PQ profiles. Our default PQ profile now signals it is one with CICP, while having a simple tonemapping as the default ICC transform for fallback. As far as we know, Adobe products also use CICP in ICC, so it also brings some compatibility there.
  2. We also now support HDR10 metadata directly in the image. If the image is a floating point image, you can now go into edit → image properties → HDR metadata to calculate the MaxContentLightLevel, MaxFrameAverageLightLevel, setup the color volume, etc. This replaces the similar menu in the ffmpeg export options.
  3. We now have CICP and HDR metadata support for PNG. This means that if you have a floating point image you can export it as Rec 2100 PQ directly, and then open it in chromium with support. You will have to wait till tomorrow, so the nightly is build, for testing.

For the PNG export, it would be great if there was some testing. We’re worried that the UI is vague. For example, maybe people would prefer it if we exported both ICC and CICP instead of only one-or-the-other, because that could allow better fallback for non-CICP supporting output. We’re unsure if it is better to have both cicp and icc or only one or the other.

Thing is, whatever we choose here, can then be applied to the heif and jpegxl export as well, so it’d be good if we can nail it down for PNG.

On top of that, I’ve got a initial gamut and tone mapping filter here. You can get test it by selecting the artifacts after the pipeline status (Direct links:Linux qt6, Windows qt6, both contain the PNG export too). The filter is under filters->color.

Right now, it is not possible to have tone/gamut mapping as a filter layer, because there’s a ton of different gamut mapping and tone mapping methods out there, and if we support them on a filter layer, we’re forced to always support them. But I would like it if people could try them out to see if I’m going in the right direction.