Comment by floatingatoll | Hacker News Reader

Comment by floatingatoll | Hacker News Reader

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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/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

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.

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.

NSL is a typo for NCS.

Y'all might want to read this:

https://arxiv.org/abs/1802.06067

(Implementation: 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

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

My implementation from a few weeks ago 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.

>My implementation from a few weeks ago >https://observablehq.com/@jrus/cam16

Nice, thanks for sharing! You seem to work on a lot of stuff I find highly interesting! :) entirely off topic, but, you might find this of interest to your logarithmic spirals work:

https://link.springer.com/article/10.1007/s00004-015-0285-1

>But for converting colors from sRGB to a wider-gamut display there shouldn’t be any significant issue.

I agree, but I'd prefer it if eventually, we treated sRGB colors the same way we treat CGA colors. Especially due to the issues outlined in the other paper I linked. (Namely, that our 'red' subpixels ain't red, they're more orange-red, and that the 'green' ones ain't green either, they're more yellow-green. Really a shame Sharp messed up their tech in that regard by just using a standard back-light, it put a huge blemish in the quite sane idea of having yellow subpixels.)

But, at the moment, we don't even have Chrome properly supporting ICCv4 profiles, so, those dreams of the far future will have to wait.

>This seems largely irrelevant to the discussion in this thread.

>largely

Yes, I agree, I placed it there as a note of caution about:

1. Limitations in the works linked to;

2. The fact that color science doesn't seem to account for stereoblindness and monocular vs. binocular stimulii more often than not;

that's all.

That's also why I linked that PhD dissertation, which also goes beyond CAM16. I in fact neglected to mention some other limitations, namely, that it also doesn't fully factor in:

1. The works on color perception by Brian P. Schmidt¹ et al.: https://bps10.github.io/ (Note: It does factor it in /in part/)

2. More esoterically (by which I DON'T mean pseudoscientific.) the ones noticed by John Medeiros: https://www.youtube.com/watch?v=4Oj0hweYE00

¹ NOT the Brian P. Schmidt who won part of the 2011 Physics Nobel price

Edit: Almost entirely off-topic, but, I try to keep my thematically related Hacker News comments at least indirectly hyperlinked to each other, so, here, another color related comment:

https://news.ycombinator.com/item?id=20008969

Reply on news.ycombinator.com