Comment by gardaani
2 days ago
> Oklab is a nightmare in practice - it's not linked to any perceptual color space, but it has the sheen of such in colloquial discussion. It's a singular matmul that is supposed to emulate CAM16 as best as it can.
Oklab is perceptually uniform and addresses issues such as unexpected hue and lightness changes in blue colors present in the CIELAB color space. https://en.wikipedia.org/wiki/Oklab_color_space
Oklab is used in CSS because it creates smoother gradients and better gamut mapping of out-of-gamut colors than Lab. Here's a picture how Oklch (on the left) creates smoother gamut mapping than CIE Lch (on the right) ("Explore OKLab gamut mapping in oklch"): https://github.com/w3c/csswg-drafts/issues/9449#issuecomment...
Oklab is not perceptually uniform. It's better than other color spaces with equally simple conversion functions, but in the end, it was created as a simple approximation to more complex color spaces, so compared to the best you could do, it's merely OK (hence the name).
> Oklab is not perceptually uniform
By what metric? If the target is parity with CAM16-UCS, OKLab comes closer than many color spaces also designed to be perceptually uniform.
If the target is parity with CAM16-UCS, CAM16-UCS is best, tautologically. Sure, if you need a fast approximation, by all means fall back to Oklab, but that optimization isn't going to be necessary in all cases.
4 replies →
> Oklab is perceptually uniform and addresses issues such as unexpected hue and lightness changes in blue colors present in the CIELAB color space. https://en.wikipedia.org/wiki/Oklab_color_space
This isn't true. Oklab is a singular matmul meant to approximate a perceptually accurate color space.
> Oklab is used in CSS because it creates smoother gradients and better gamut mapping of out-of-gamut colors than Lab.
That's not true, at all. Not even wrong. Gamut mapping is separate from color space.
> Here's a picture how Oklch (on the left) creates smoother gamut mapping than CIE Lch (on the right)
I love the guy who wrote this but we have an odd relationship, I'd have people tell me all the time he wondered why I wasn't reaching out to him, and we've never met, he's never contacted me, etc.
If you're him, we should talk sometime.
I doubt you're him, because you're gravely misunderstanding the diagram and work there. They're comparing gamut mapping algorithms, not comparing color spaces, and what is being discussed is gamut mapping, not color spaces.