Re: [csswg-drafts] [css-color-4] Gamut Mapping with Oklch - Odd Results (#7071)

@facelessuser  wrote:
> I just figured it was worth bringing up as a discussion point.

Oh, it certainly is worth bringing up, thanks for doing so.

Worth pointing out that interpolation in a polar space is frequently going to produce out of gamut intermediate colors, because of the irregular gamut shape of all RGB spaces. We have a way to take a straight line between two points (use a rectangular space for interpolation) and to take the maximal-chroma arc, but not a way to take a shallower arc (apart from adding intermediate stops).

On a first glance, the flat area in the OKLCH-mapped CIE LCH interpolation is troubling; it is as if the whole area has a single hue (in OKLCH) but different hues in CIE LCH. But then one might expect to see a similar effect for the CIE LCH-mapped OKLCH interpolation.

I need to investigate this more deeply, with a look at the numerical values for the generated interpolation and for the gamut-mapped results, at key points along the gradient.

@romainmenke wrote:

> LCH result seems to correlate with what you can see here in the top left corner :

Looking at your page, was the first column generated in coloraide too, like this:

```js
color.convert('oklch').fit('srgb', method='oklch-chroma').convert('srgb').fit('srgb', method='clip').coords();
```

or by some other method?

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Received on Tuesday, 22 February 2022 23:18:08 UTC