Is there a metric for “apparent” chroma?

I’m not sure this is the right place to ask, but is anyone aware of a metric for apparent chroma?

Now I understand that “chroma” and “chrominance” are very overloaded terms, so to clarify, I specifically mean the chroma described here–the “colorfulness relative to the brightness of a similarly illuminated white”. At full saturation this should be 255. At any black/white/gray it should be 0. And the closer a lightness is to the ends of the spectrums, the lower the maximum chroma (in contrast to the inverse of saturation where it is always 255). Basically chroma is the lateral dimension of the HSL bicone.

Unfortunately, this color model makes no corrections for perceived chroma–that is, how our imperfect eyes perceive equal chromas differently based on hue (e.g. #FFFF00 does not appear as chromatic as #0000FF).

So my question is, is there such a metric? Or can anyone point me to an academic paper on the subject? My own searches have turned up nothing, not helped by the multiple definitions of “chroma”.

For the curious, my objective is to establish a general approximation of “jarringness” for colors of text and backgrounds of websites, working on the theory that apparent chroma is a significant factor.


Ah, after some more searching, I found it on my own! It appears I was specifically looking for Munsell chroma, CIELAB LCH’s chroma, or UP Lab chroma (all basically attempts to get at the same idea).

Unfortunately, converting between sRGB and Munsell chroma is non-trivial and UP Lab chroma copyrighted, but it looks like sRGB -> LCH is not too difficult.

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