Re: [csswg-drafts] [css-color-4] Channel clipping breaks author expectations, especially when using 'perceptually uniform' spaces (#9449)

In looking into the interpolation question brought up by @eeeps, it does look like you would lose some of the perceptual uniformity of the chroma channel.

For instance, if we have a gradient between `oklch(50%, 50% of display-p3, 250)` (blue) and `oklch(50%, 50% of display-p3, 280)` (purple), the chroma would increase from roughly `.1` to `.15`. Despite a constant Chroma value, the [gradient](https://gradient.style/#type=linear&space=oklab&linear_named_angle=to+right&linear_angle=90&stops=%7B%22kind%22%3A%22stop%22%2C%22color%22%3A%22oklch%2850%25+0.1+250%29%22%2C%22auto%22%3A%220%22%2C%22position1%22%3A%220%22%2C%22position2%22%3A%220%22%7D&stops=%7B%22kind%22%3A%22hint%22%2C%22auto%22%3A%2250%22%2C%22percentage%22%3A%2250%22%7D&stops=%7B%22kind%22%3A%22stop%22%2C%22color%22%3A%22oklch%2850%25+0.15+280%29%22%2C%22auto%22%3A%22100%22%2C%22position1%22%3A%22100%22%2C%22position2%22%3A%22100%22%7D) would appear to have an increasing chroma.
 
<img width="506" alt="image" src="https://github.com/w3c/csswg-drafts/assets/167908/c87c752d-ca72-436d-8ea6-31ebd2135d3f">

Larger hue differences would show swings back and forth in chroma. 

This may be a reasonable tradeoff, as many of the proposed algorithms preserve lightness and hue over chroma, as those are the most informative channels.

From an author's perspective, I do see some confusion over the meaning of 100% when it maps to a value that is a function of Lightness and Hue.

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Received on Wednesday, 14 February 2024 19:52:43 UTC