The advantage of using a rainbow scale as opposed to a gray scale is that a rotation in hue space brings out more 'detail' than a simple black to white gradient.
I still think it's a bit visually confusing when you're representing the existence or non-existence of something (the planet is in this region, and not anywhere else)
You could in theory do both.. rotate in hue and fade to white. If you did it right, when if you printed it out in B&W you'd get the grayscale equivalent :)
That was a very interesting read. Thank you for sharing. I could really use some of the other color spaces presented too.. in some other situations.. I'll just need to figure out how to plug them into my workflow :)
It's strange but the first linear color space (CET-L03 red-yellow-white) seems to go to a lightness of 100. On the far right it looks white as expected. However the other one (CET-L20) looks very nice, but it doesn't seem to reach 100. Even though in the plots and explanation it suggests it does. Strange..
The more I look into this the more it seems this inevitably (accidentally or intentionally) misrepresents data. Even the author highlights how it does this. All the options are in some ways effectively thresholding/binning ... but in non-systematic ways through the vagaries of the human visual system. Unless this is an art project, there are more systematic and honest ways to bin things.
I can see how it can be useful or even inescapable in some situations.. The most obvious being maps with different content that needs to be distinct and of course these bimodal "divergent color maps". But maps are already half-art :) and bimodal data you're effectively vaguely "pre-binned" the data into two equal halves. There are also situations where the color is adding an extra dimension (like these "cyclic colour maps"). The result with the fingerprint is honestly hard to visually interpret, but I don't see any clear alternative (other than a grid of arrows I guess)
But reading all this stuff leaves me with the impression that colors are dangerous. They really should be last resort. In simple/common situation like the probability densities of the mystery planet - grayscale looks like it's the only really honest option. Side by side with the grayscale, the linear colors don't seem to be adding all that much and are creating artificial "islands" (not to mention the colors are a real blast to the eyeballs)
