[snibsnib]

I used to work in a paint lab. You are correct, oklch seems to be based off CIELCh.

Our eyes are much more sensitive to Blue/Violet, and less sensitive to green. There's a bunch of maths behind the perceived responses of our eyes.

If you're interested you can calculate perceived differences in the LCh colorspace using something like CIEDE2000.(https://en.wikipedia.org/wiki/Color_difference#CIEDE2000)

A Rainbow with equal DE between colors would probably look better than this one with equal DL.

[jacobolus]

For purposes like graphic design or color grading it's usually more useful to first focus on lightness contrast, then pick hue and chroma afterward. Having uniform steps of ΔE is not really important, and using that as a primary criterion will usually make for worse choices. Color is multidimensional and trying to simplify it to a single distance function is substantially misleading for this context.

The main purpose of ΔE is specifying error tolerances for specified colors / measuring small differences between nearby colors, so that e.g. if you hire someone to paint a car or print a magazine you can check that their output matches expectation sufficiently. For colors that are significantly different ΔE isn't that helpful a practical tool.

[Sharlin]

> Our eyes are much more sensitive to Blue/Violet, and less sensitive to green.

Hm? It's the exact opposite. That's why the full-intensity RGB green looks much brighter than the full-intensity blue. To convert RGB to pure luminance (gray), you do something like 0.3 * R + 0.6 * G + 0.1 * B, meaning green contributes six times as much as blue.