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Comment by weinzierl | Hacker News Reader

Unfortunately the link in the article to HSLuv is down, but it seems it is based on CIELUV. CIELUV is what people thought of perceptually uniform in 1976, a time when computers were not widespread. We have much better color models now.

What I never understood however is that even with the most advanced models the color difference is apparently never simply the euclidean difference. This is fine if you just want to calculate deltaE, but not so helpful if you want to do diagrams.

Is there an up to date color model that is perceptually uniform and an euclidean space?

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No, it’s not possible to have uniform color differences at all scales and in all directions in a 3-dimensional Euclidean space. If you go around a hue circle in little steps and then sum up all the perceived color differences you end up with more than π times the sum of differences you get if you go across the circle through gray.

Is that implying that you could have uniform model in higher-dimensional space? Afaik there isn't really any particular reason why we should be limited to three dimensions.

Sure, you could make your 3-dimensional color space a manifold with negative curvature embedded in a higher-dimensional Euclidean space.

A quick google scholar search turned up https://www.osapublishing.org/oe/abstract.cfm?uri=oe-22-10-1... but there are plenty of other sources discussing similar topics.

My math is a bit rusty but isn’t a manifold locally Euclidean? The GP is talking about how we can’t have Euclidean difference.

A sphere and a hyperboloid are both locally Euclidean (as is color space). The interesting stuff starts to happen as you move around a bit further in the space.

I think it's a bad link. I found it within the URL: http://www.hsluv.org

Actually, the link is just wrongly formatted, the HSLuv project is online: http://www.hsluv.org/

> We have much better color models now.

Care to share?

I would recommend IPT or CIECAM02.

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