Comment by refulgentis
5 days ago
I've done work that, for better or worse, required creating a color space.
It to enable dynamically generated UI palettes that also were numerically verifiable as accessible.
The way I model color blindness for a quick & cheap heuristic is, remove all hue-ness and saturation-ness. i.e. make the scene black and white.
That elides the exact compression in hue that is experienced by an actual individual (i.e. is it just red on green that's a problem? tetrachromate or x or y or z? at what severity (this is ~unmeasurable)) and leaves you with the raw problem, that there isn't sufficient contrast between the two colors.
Even though this elides information about the individual's exact experience, it is crucial for how to think about color, because even if color blindness didn't exist, it still would affect all of us
A cheap example of that is #FF0 text on a white background. Yellow is absurdly close to white (IIRC 97 L* versus 100 L*), so you can never quite focus on the yellow, it feels like its slippery and you get a headache trying to read.
(w/the tree x cardinal example, red is ~43? L*. A natural green w/o an absurd sunlight behind it would be somewhere around 55 L*. You want about 40 L* for good contrast, here we have ~10 L*, and once you lose the hue/saturation delta due to color blindness, it's quite difficult for the bird to "jump out", as it were. you could still find it scanning)
That's the suggestion I give to designers so don't take this as criticism, but monochromatic contrast isn't perfect either. Some forms of colorblindness actually experience a shift in luminance that depends on the color and their specific perception. Things that are distinguishable by contrasting brightness (e.g. black text on white background) may become ambiguous if those colors are changed to e.g. green and red respectively, even if the lightness contrast remains the same because they'll perceive the red as darker than it truly is.
This is specific to the person, so there's no real way fix for everyone beyond turning everything into extreme differences like pure black and white. It's just something to note about the limits of it as an accessibility technique.
Red gives me nightmares, ugh. I hacked up my personal version of our algo to only pair it with white