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Comment by pansa2 | Hacker News Reader

Isn’t CIELUV more-or-less deprecated now, in favour of CIELAB?

Is there a reason that HSLuv is based on the former (and isn’t “HSLab” instead)?

AB coordinates are a bit unintuitive, it's easier to visualize hues around a circle and have separate values for luminance and chroma, that's why people who work with color usually prefer LCH/HCL (Luminance, Chroma, Hue).

Chroma values in LCH differ between Hues, because each Hue has a different potential and max value. That's where HSLuv comes in, where chroma is a percentage value and therefore relative to the Hue, instead of an absolute one. This gives HCL similar usage ergonmics like HSL, thus the name HSLuv.

But it’s possible to construct an LCh color space from either CIELAB or CIELUV. Why choose the one that’s less widely-used?

Sure, but chroma is absolute in LCh, which makes it hard to use for color generation. 100% chroma in HSLuv is the highest value of a particular hue in LCh.

I've never figured out why LAB and LUV both exist, they were created around the same time to solve the same problem. LAB is definitely more popular though.

CIE recommend the use of LAB for paints/dyes/surfaces, and LUV for displays.

I don't know why. I just know they do.

If I had to guess, it would be that LUV is designed for additive mixing, and LAB is not, but that is a guess educated by some dimly remembered early highschool physics along with 4th grade art lessons.

This is a common misconception; both were recommended because they performed equally well on available data at the time [1]. While CIELUV does have the advantage that additive mixtures fall on straight lines in its chromaticity diagram, it does poorly at predicting color differences and has a flawed adaptation transform, so CIELAB is generally preferred.

[1] https://doi.org/10.1002/col.5080150308

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