Re: [csswg-drafts] [css-color-4] Missing info about Premultiplication and Undefined values (#7536)

So, this is starting to get a bit confusing:

> If a color with a [missing component](https://drafts.csswg.org/css-color-4/#missing-color-component) is interpolated with another color **which has that component, and the value is not missing**, the missing component is treated as having the other color’s component value.

So, are we comparing these colors before they are converted to the common color space? If I'm comparing an sRGB color with a Rec 2020 color that has different scaling, the sRGB color need to take on the red value from the Rec 2020 color? You seem to mention these surprising results with hues not being compatible and scales, I'm not sure I like this approach very much. Color spaces may share the same components, but they are not exactly the same in meaning. They may have different primaries for example.

I feel if people are trying to use `none` to their advantage, it would be best that they work with their colors in a consistent color space to take advantage of the `none` and avoid `none` to zero translation.

If the intent is to special case `alpha` specifically, I can more see that as a possibility. It is independent of color conversions and definitions of color spaces. I remember some suggesting the possibility of making `alpha` resolve to 1 instead of zero for instance. I could see an undefined `alpha` reasonably being treated specially during a conversion process and not altered, and then only at display time resolved to some sane, viewable value. I'm just not sure I personally see much of a benefit to complicating the conversion process for non-alpha components.


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Received on Saturday, 30 July 2022 14:58:49 UTC