The integrity of the argument may be harmed somewhat by the use of an inferior gradient blending technique. Eyeballing Figure 3, the gradient interpolation is l

The integrity of the argument may be harmed somewhat by the use of an inferior gradient blending technique. Eyeballing Figure 3, the gradient interpolation is linear, which is a common but bad technique. https://larsenwork.com/easing-gradients/ https://larsenwork.com/easing-gradients/ shows some nice examples of the problems and the proper easing technique. Moreover, looking at the green–red gradient especially, I think the interpolation may have been done in sRGB space, which is awful for these sorts of things (on the other hand, they do call it isoluminant green–red, so I may be missing the mark in my sRGB guess—it’s hard to be sure by just eyeballing). On the matter of such colour spaces, https://raphlinus.github.io/color/2021/01/18/oklab-critique.html https://raphlinus.github.io/color/2021/01/18/oklab-critique.... has the best tool for demonstration and comparison that I know of. The techniques employed harm the rainbow gradients significantly, making them far less smooth than they would be with better interpolation, even with the same colour stops. On that point, the first row of that diagram feels more like a straw man than an honest comparison—it shows massive and uneven colour bands which I don’t think is entirely artefacts of the gradient interpolation. I will admit that users of rainbow colour maps are more likely to interpolate poorly and not space colours evenly, but still, I wish the article had done as good a job as possible on the rainbow colour map, to show that even then it’s still problematic.