There is some recent research I found that models this effect and applies an additional transform to account for it, building off of work from Fairchild MD, Pirrotta E in the 90’s. The end result is labeled as the “Predicted Equivalent Achromatic Lightness”, or in other words “The lightness of the gray that most closely matches the perceived lightness”.
This is actually quite a useful value, because it’s precisely the value we want when desaturating an image! Most desaturation operations spit out a [0..1] value which is then (later) rendered as an RGB gray color. Using the L_EAL value instead jumps us right to the end, giving the exact perceptual gray color to place in the resulting desaturated image.
How much of an issue is this? Well, I noticed. I’ve been writing a tool to desaturate game screenshots, to help us evaluate relative brightnesses between art assets, and improve overall game readability. All of the red assets appeared.. strangely dark in the desaturated images, even when using CIELAB!
