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Why does the chromaticity diagram look like that?

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276 points samwillis | 1 comments | 26 Jul 24 18:19 UTC | HN request time: 0.207s | source
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mncharity ◴[27 Jul 24 00:10 UTC] No.41083489[source]▶
Does anyone know of a nice "pedagogical" color space? That is, one optimized for teaching and learning, for correctness rather than for simple math? Where the space's highly-noticeable characteristics are actual features of human perception, rather than the usual mess of "nope, that too is a model artifact" (mostly from optimizing for computation). And full-gamut, well behaved out to spectral locus. And with at least somewhat linear hues and color combination. Sort of the Munsell niche, but full gamut, and this century.

I wasn't able to find anything even close, for a "maybe teach color better by emphasizing spectra?" side project, so I kludged. CAM16UCS as state-of-the-art for perceptual color, untwisted with Jzazbz for linear hues (it also sanity checked absolute luminosity), with a rather-unprincipled mashing down of CAM's IIUC-non-perceptual near-locus silly blue tail. Implemented as lookup tables. If there is any related work out there, I'd love to hear of it. Tnx.

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Daub ◴[27 Jul 24 07:12 UTC] No.41084960[source]▶
> Does anyone know of a nice "pedagogical" color space? Where the space's highly-noticeable characteristics are actual features of human perception

When talking with students about color, I find the HSL space the easiest to employ. From a color maths point of view I have been told that it is very messy, which is one reason why Adobe stopped using it in version 3 of Photoshop. But from the perceptual point if view, it is the artists favorite.

Perhaps a better option is the Muncell color space. Muncell chopped up the entirety of the color domain into thousands of small chunks. The distance between each chunk was a single units of 'barely perceptual difference' which he established through meticulous user testing. Hence the green domian was much larger than the yellow. The story behind his development of this space makes for facinatting reading. He was an artist (a painter) yet his work paved the way for more modern spaces.

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1. mncharity ◴[27 Jul 24 14:16 UTC] No.41086757[source]▶
> When talking with students about color, I find the HSL space the easiest to employ. [...]

Nod. I was exploring how/whether an emphasis on spectra might be used to more successfully explain and teach color. Motivated by observations of wide-spread profound failure, like first-tier graduate students saying "the Sun doesn't have a color; it's rainbow color", and color instruction content, err, exercising diverse artistic license. So I'd hoped for Munsell-like web interactives, but with principled coupling to spectra. Hopefully as easily understood as HSL, if less convenient as a more-abstracted artist UI. I like implicit curriculum ("things noticed in passing provide insight and invite exploration"), and am leery of science education graphics' traditional "some aspects done with great care for correctness, mixed with others of utter bogosity, with students unable to tell which is which". And so wanted to avoid the high-profile "no, that too is merely a model artifact, not reality" of say CIE 1931 chromaticity diagrams ("such tiny sRGB coverage!", "so much green!", "a prism shaped solid!"). And also its frequently sloppy graphics (incorrect colors, misleading handling of out-of-gamut colors, misplaced white point not intersected by blackbody curve). I had hope for linear-hue absolute-physical-brightness Jzazbz, but meh[1]. Perception-optimized wide-gamut recent CAM16 seems unsurprisingly closest to this vision, but for some "hmm, is that bit real or model?", and "how does this behave with changes in absolute illumination?". A tweaked CAM16-UCS can end up a seemingly unobjectionable swelling blob. The scattered instances of intensive use of Munsell in art instruction suggested at least some hope of clarity and utility. Thanks for the thoughts.

[1] https://user-images.githubusercontent.com/181628/61452533-43... [png] from https://github.com/coloria-dev/coloria/issues/41