Re: [csswg-drafts] [css-color-4] parsed-value-time lightness clamping (#11549)

> The current wording prevents specifying colors brighter than media white, whereas those can currently be specified in HSL, XYZ, and the various RGB models. Would it make sense to drop the required parsed-value time clamping of lightness for the perceptual models Lab/Lch/Oklab/Oklch?

That sounds like you are trying to extend CSS Color 4 to handle (some aspects of) HDR. CSS Color 4 is explicitly for SDR colors.

We already have [a spec for HDR colors](https://drafts.csswg.org/css-color-hdr-1). In particular, colors are specified as an (HDR, SDR) pair each with associated headroom.

So for example

```css
color-hdr(
    color(display-p3 1 1 0.33) 0,
    jzczhz(70% 0.14 100) 3
```

the HDR color is used where there are 3 stops of HDR headroom, the SDR where there are zero stops (SDR) and for intermediate values of headroom, the [colors are interpolated](https://drafts.csswg.org/css-color-hdr-1/#headroom-interpolation).

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Received on Friday, 23 January 2026 21:27:33 UTC