- From: Jeffrey Yasskin via GitHub <sysbot+gh@w3.org>
- Date: Thu, 04 Apr 2024 17:03:56 +0000
- To: public-css-archive@w3.org
> > ... a gamut-mapping rule of the form "minimize the perceptual difference between the specified and displayed color while preserving hue". > > That is not testable so making such a statement normative means very little. I had trouble finding the tests for what's currently in the spec. https://www.w3.org/TR/css-color-4/#css-gamut-mapping just says "Used values of color are not exposed to script, making this hard to test in an automated manner." Given a way to measure the output, I think one could test this with a rule that "the output color has to have a ΔΕ < X from the in-gamut color of the same hue as the target color with the least ΔΕ from the target color." > I think what most use cases share in terms of goals is the desire to minimize the difference between the two colors. ... I think a goal framed around minimizing ΔΕ (for some ΔΕ algorithm) is likely the best default here, with opt-ins that make different tradeoffs. > ... > does [Chris C] want [image matching] to be the _default_ or just _possible_? I'm trying to figure this out too, and in particular, what would go wrong if it's not the default. That said, if CSS does wind up preferring a "minimize the ΔΕ from the specified color" goal, that matches what @ccameron-chromium has said he can accept for images, so maybe we can actually have a compatible default. +1 for other opt-ins, especially the "preserve contrast" one. > I literally [asked](https://github.com/w3c/csswg-drafts/issues/9449#issuecomment-1967827846) @ccameron-chromium if he would be ok with _precisely_ that and [he said no](https://github.com/w3c/csswg-drafts/issues/9449#issuecomment-1978836522), that he wants the bulk of the gamut mapping operations to be anything goes with only the tiny bit at the end being normative. I'm hopeful that the "prefer" in his March 5 answer, and his more recent March 27 statement that "... and we'd go implement it!" indicates some room to compromise. -- GitHub Notification of comment by jyasskin Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/9449#issuecomment-2037737040 using your GitHub account -- Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config
Received on Thursday, 4 April 2024 17:03:57 UTC