Re: [csswg-drafts] [css-color] Discussion of Conflicts & Resolutions: D50/D65, LAB/LUV, ICC/OCIO (#6061)

> All I was trying to establish is whether there was some theoretical bounds on Lab that I was unaware of that didn't also apply to XYZ. 

XYZ has a theoretical non-negative bound (but in practice, enforcing that affects round-tripping so should not be done).

Lab has a clear bound at L=0 (but again, round-tripping is enhanced if that is not enforced) and is defined to be relative to the current adapted white at L=100. That implies that specular whites should be at L > 100, so CSS Color 4 carefully allows values > 100; but it is not clear that the cube-root L power law is appropriate above media white.

a and b are theoretically unbounded. Some implementations impose arbitrary limits. One notable implementation enforces 128 to -127 which arbitrarily clips real, useful colors. Pointers surface gamut exceeds that, for example; and real-world content can easily have colors outside the surface gamut.

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Received on Tuesday, 2 March 2021 17:10:21 UTC