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It is emphatically not “literally the exact [...] triangle”. The NCS is a similar concept, but executed based on a plausible theoretical model and (more or les

It is emphatically not “literally the exact [...] triangle”. The NCS is a similar concept, but executed based on a plausible theoretical model and (more or less) sound empirical study of human perceptual response to visual stimuli. “HWB”, like HSL, is just someone’s trivial half-assed transformation of the RGB cube, completely ignoring more than a century of color science research. It’s what you get when a person off the street were tasked with redefining the NCS, without understanding it. It reminds me of people’s bicycle sketches, http://www.gianlucagimini.it/prototypes/velocipedia.html http://www.gianlucagimini.it/prototypes/velocipedia.html Personally I am not the biggest fan of the NCS system for designating colors; I find Munsell-like coordinate systems to work better for me, in practice. But at least it has some kind of theoretical and empirical basis.

floatingatoll 7y ago
This paper from a few years ago compares various mathematical definitions of "hue" that have been popular over the past few decades. https://pdfs.semanticscholar.org/7833/f96c09a1201f0e7f54e0de662e4faef36276.pdf https://pdfs.semanticscholar.org/7833/f96c09a1201f0e7f54e0de... CSS, having already standardized on Munsell hue circles (page 5) in the past, appears content to continue forward with them as the hue circle of choice for HWB. While I respect that you would prefer to see them use the NSL hue circle (pages 10-11), it appears that they are unlikely to do so at this time. One bonus find here is the abstract for the cited Whitfield (1988) paper, where the paper's authors attempted to replicate the assertion that NSL is better than Munsell, and failed: https://onlinelibrary.wiley.com/doi/10.1002/col.5080130210 https://onlinelibrary.wiley.com/doi/10.1002/col.5080130210 The study reported here is a replication of experiments cited as support for this claim. Subjects were trained in the NCS using NCS training material and carried out colour‐identification tasks. For comparison, a further subject group was trained in the Munsell system and carried out identical tasks. The results indicated (a) a lower level of accuracy than previously reported for those subjects trained in the NCS and (b) little difference in performance between the NCS‐ and Munsell‐trained groups.
- jacobolus 7y ago
  What are you talking about? CSS has nothing to do with Munsell hues or NCS hues. I have no idea what you mean by “NSL”. The “HSL” / “HWB” hue circle is just a trivial transformation of the RGB cube (namely: zigzag along the 6 most colorful edges of the cube at constant speed), designed by non-color-expert computer programmers based on what was convenient to implement on workstation computers from the late 1970s (note: these considerations are not relevant 40 years later), and has almost nothing to do with human perception. It is nowhere near perceptually uniform (unlike the goals of Munsell hues), and also does not have human-perception-meaningful landmarks like the NCS cardinal directions. If you follow a circle of constant “W” and “B” in the “HWB” model, at constant speed in terms of “H”, then a typical human observer will see wildly varying “lightness”, “colorfulness”, “saturation”, “whiteness”, “blackness” with respect to their own perception, and will see perceived hue change at highly irregular and unsmooth speed.
  - floatingatoll 7y ago
    NSL is a typo for NCS.
  - no_identd 7y ago
    Y'all might want to read this: https://arxiv.org/abs/1802.06067 https://arxiv.org/abs/1802.06067 (Implementation: https://github.com/nschloe/colorio https://github.com/nschloe/colorio ) And this (read the Appendix on the BACKLIGHT of the Sharp Quattron, and take a look at Figures 1.3, 3.5, 9.2, G.3!): Note however, that all of this completely ignores the fact that humans seem capable of some form of HDR color fusion via binocular vision, as impressively demonstrated in this paper: http://arxiv.org/abs/1703.04392 http://arxiv.org/abs/1703.04392 Given that many people seem to report slight differences in monochromatic color differentiating between eyes, we can speculate that binocular vision influences color perception in some way. Edit: See also my comment here: https://news.ycombinator.com/item?id=19983432 https://news.ycombinator.com/item?id=19983432
    - jacobolus 7y ago
      My implementation from a few weeks ago https://observablehq.com/@jrus/cam16 https://observablehq.com/@jrus/cam16 (Make sure you watch for typos in your link.) But frankly using CIECAM02 or CAM16 (or whatever) vs. CIELAB for doing gamut mapping is a relatively minor improvement in most cases. There can be serious issues when trying to convert RGB images to CMYK or similar for printing, especially hue shifts in the blue–purple region. But for converting colors from sRGB to a wider-gamut display there shouldn’t be any significant issue. The big problem is that historically most browsers have done no color management of CSS colors. Looks like that is now changing, which is encouraging, whether or not the gamut mapping algorithm they use is state-of-the-art. > ignores the fact that humans seem capable of some form of HDR color fusion This seems largely irrelevant to the discussion in this thread.

floatingatoll 7y ago

This paper from a few years ago compares various mathematical definitions of "hue" that have been popular over the past few decades. https://pdfs.semanticscholar.org/7833/f96c09a1201f0e7f54e0de662e4faef36276.pdf https://pdfs.semanticscholar.org/7833/f96c09a1201f0e7f54e0de... CSS, having already standardized on Munsell hue circles (page 5) in the past, appears content to continue forward with them as the hue circle of choice for HWB. While I respect that you would prefer to see them use the NSL hue circle (pages 10-11), it appears that they are unlikely to do so at this time. One bonus find here is the abstract for the cited Whitfield (1988) paper, where the paper's authors attempted to replicate the assertion that NSL is better than Munsell, and failed: https://onlinelibrary.wiley.com/doi/10.1002/col.5080130210 https://onlinelibrary.wiley.com/doi/10.1002/col.5080130210 The study reported here is a replication of experiments cited as support for this claim. Subjects were trained in the NCS using NCS training material and carried out colour‐identification tasks. For comparison, a further subject group was trained in the Munsell system and carried out identical tasks. The results indicated (a) a lower level of accuracy than previously reported for those subjects trained in the NCS and (b) little difference in performance between the NCS‐ and Munsell‐trained groups.

jacobolus 7y ago
What are you talking about? CSS has nothing to do with Munsell hues or NCS hues. I have no idea what you mean by “NSL”. The “HSL” / “HWB” hue circle is just a trivial transformation of the RGB cube (namely: zigzag along the 6 most colorful edges of the cube at constant speed), designed by non-color-expert computer programmers based on what was convenient to implement on workstation computers from the late 1970s (note: these considerations are not relevant 40 years later), and has almost nothing to do with human perception. It is nowhere near perceptually uniform (unlike the goals of Munsell hues), and also does not have human-perception-meaningful landmarks like the NCS cardinal directions. If you follow a circle of constant “W” and “B” in the “HWB” model, at constant speed in terms of “H”, then a typical human observer will see wildly varying “lightness”, “colorfulness”, “saturation”, “whiteness”, “blackness” with respect to their own perception, and will see perceived hue change at highly irregular and unsmooth speed.
- floatingatoll 7y ago
  NSL is a typo for NCS.
- no_identd 7y ago
  Y'all might want to read this: https://arxiv.org/abs/1802.06067 https://arxiv.org/abs/1802.06067 (Implementation: https://github.com/nschloe/colorio https://github.com/nschloe/colorio ) And this (read the Appendix on the BACKLIGHT of the Sharp Quattron, and take a look at Figures 1.3, 3.5, 9.2, G.3!): Note however, that all of this completely ignores the fact that humans seem capable of some form of HDR color fusion via binocular vision, as impressively demonstrated in this paper: http://arxiv.org/abs/1703.04392 http://arxiv.org/abs/1703.04392 Given that many people seem to report slight differences in monochromatic color differentiating between eyes, we can speculate that binocular vision influences color perception in some way. Edit: See also my comment here: https://news.ycombinator.com/item?id=19983432 https://news.ycombinator.com/item?id=19983432
  - jacobolus 7y ago
    My implementation from a few weeks ago https://observablehq.com/@jrus/cam16 https://observablehq.com/@jrus/cam16 (Make sure you watch for typos in your link.) But frankly using CIECAM02 or CAM16 (or whatever) vs. CIELAB for doing gamut mapping is a relatively minor improvement in most cases. There can be serious issues when trying to convert RGB images to CMYK or similar for printing, especially hue shifts in the blue–purple region. But for converting colors from sRGB to a wider-gamut display there shouldn’t be any significant issue. The big problem is that historically most browsers have done no color management of CSS colors. Looks like that is now changing, which is encouraging, whether or not the gamut mapping algorithm they use is state-of-the-art. > ignores the fact that humans seem capable of some form of HDR color fusion This seems largely irrelevant to the discussion in this thread.