Re: [csswg-drafts] [css-color-6] contrast-color() and gamut mapping (#8539)

The CSS Working Group just discussed `[css-color-6] contrast-color() and gamut mapping`, and agreed to the following:

* `RESOLVED: To use the actual displayed color when calculating contrast`

<details><summary>The full IRC log of that discussion</summary>
&lt;emeyer> chris: We can either say you do contrast between the color you can see and another color, or we say it’s between something that might not be a color and some other color<br>
&lt;emeyer> lea: We need to hear from implementors whether this is possible<br>
&lt;emeyer> chris: I did touch on that in the issue; we don’t expose the used value of a color and don’t need to for this<br>
&lt;emeyer> lea: Not concerned about fingerprinting, I’m concerned about whether all ODes can do this<br>
&lt;emeyer> TabAtkins: They’ll have what they used to present to the monitor<br>
&lt;emeyer> lea: Do colors get gamut-mapped to something they can present?<br>
&lt;Rossen_> q?<br>
&lt;emeyer> TabAtkins: Not sure<br>
&lt;emeyer> lea: We could conditionally resolve, saying we’ll do something if it’s actually implementatble<br>
&lt;chrishtr> hi<br>
&lt;emeyer> chrishtr: What’s the actual proposal here?<br>
&lt;emeyer> chris: To use the actual displayed color when calculating contrast<br>
&lt;TabAtkins> (As much as that information is available.)<br>
&lt;fantasai> +1 to the proposal<br>
&lt;emeyer> chrishtr: So gamut mapping should be taken into account when doing this?<br>
&lt;emeyer> lea: The rationale being otherwise we could get calculation between two non-existent colors<br>
&lt;emeyer> Rossen_: It seems like this makes the most sense<br>
&lt;emeyer> …The question is whether you can get those, and how much work it will take to do so<br>
&lt;fantasai> s/colors/colors. Otherwise you might decide there's enough contrast, but after gamut-mapping there isn't./<br>
&lt;emeyer> …In terms of intended functionality, what Chris is proposing here makes total sense<br>
&lt;emeyer> …If implementors say this is impossible, we should drop the entire thing<br>
&lt;fantasai> +1<br>
&lt;emeyer> chrishtr: I’d like to wait a week to resolve<br>
&lt;emeyer> Rossen_: That objects to what makes sense<br>
&lt;lea> +1<br>
&lt;emeyer> …So let’s resolve on what makes sense, and if it turns out to be impossible, we revisit<br>
&lt;emeyer> RESOLVED: To use the actual displayed color when calculating contrast<br>
</details>


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Received on Wednesday, 23 August 2023 16:59:10 UTC