Re: [csswg-drafts] [css-color-hdr] CSS syntax for HDR colors parameterized by headroom (#11616)

> What about HDR images that don't use ISO 21496-1 gain maps?

There is a similar proposal in ICC that defines this mapping as a global tone map. I don't think it's share-able yet, unfortunately. It is also representable by this scheme.

Also if there is no ICC global tone map, and no other metadata, then ISO 22028-5 is working to define how this would be tone mapped "by default".

(BTW, I'd like for us to eventually have WPT tests for all 3 of these cases: gain map tone mapping, global profile tone mapping, and default tone mapping ... hopefully by the end of the year?).

> color-hdr(matching url(myImage.png)

I suspect that we'll want to provide something like the ICC global tone map as metadata also for canvases. And so I think something more like that metadata would be a better "match". There are also some parameters in the image metadata to account for the fact that image data is in [0,1] (the min/max/gamma parameters), which don't apply to CSS colors that can specify any value.

> Any thoughts on HDR video?

There is a proposal for gainmap support in AV1 video. I would like for there to be a uniform approach on global tone mapping between ICC and video as well.


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Received on Tuesday, 4 February 2025 11:17:35 UTC