The entire article including the very title explains that this is an improved version of Rainbow, of which they are very well aware and cite very clearly, and tweak for well explained reasons.

Sorry, my comment was unclear. They are comparing against jet, which is a colourmap that uses all the colours of the rainbow. They are not using the colourmap _called_ `rainbow`, to compare against.

You are right and I was wrong. The ‘rainbow’ map at the matplotlib link happens to be plotted next to ‘jet’ and the lack of perceptual banding in comparison is clear. Looks like the Google author came up with a similar idea.

Whoever gave the name ‘rainbow’ to their rainbow colormap?! It’s like naming a dog ‘dog’.

Yeah, it's not the best name. There is also the 'Spectral' colour map that is plotted in a different section, which imo is much better suited as being a diverging colour map as yellow looks more 'neutral' than bright green.

Indeed, we probably should have compared more directly to Rainbow, I got a bit of this flak on Twitter as well (with my rationale included): https://twitter.com/JamesABednar/status/1163978274361544704?...

The practical issue is that not many people really use Rainbow instead of Jet, for the reasons I mentioned in the article (it sacrifices too many of the 'good bits' of Jet). So instead I chose to compare to the more 'widely recommended' maps.

But you're right, I should have thrown rainbow into the mix, even if I didn't have the space to write about it.

Agree with you that the smoother shape leads to a more pleasing colour profile -- note that the `rainbow` cmap in matplotlib is different to the one you compared against, it's actually more similar to Turbo by looks. I would have also compared against other diverging colour maps, like Spectral and those available in `cmocean` (the latter are really beautiful).

All of this said, Turbo is quite pleasing to the eye :).

Thanks! Indeed there are a few 'rainbow' variants out there (in d3, matplotlib, matlab), and some of them are very pleasant (though I think lower contrast). I personally find it confusing to have 'pink' in a rainbow map. It's not in a real rainbow, and the way I recall the color order is by visualizing that so it trips me up :)

I like Spectral a lot as well. I think if you're not after mega contrast it's probably the best bread-and-butter map out there for this kind of work.

The article explicitly compares to the matplotlib colormaps and states the advantages of their contribution.

If you look at the post that I referenced in there (a matplotlib page detailing the colourmaps that are available in that library) there is one that is actually called `rainbow` that's very similar to the one proposed by the google team. They do compare against viridis and inferno, you're correct -- but comparing a high-contrast colour map directly to a perceptually uniform one is an unfair comparison. They should compare against, for instance, the rainbow one from there, cubehelix, or even the twilight ones that I suggested.

Of course it's always good to have other colour maps to choose from, but the similarity between this proposed one and the ones that already exist makes it seem like they've only quickly glanced at other work in the field.