rainbow colour maps

Many many years ago (long before the web was available to give me advice) I discovered a problem with rainbow colour maps that I haven’t seen mentioned elsewhere.  (There are many other problems.)

(a) rainbow, (b) gray-scale, (c) black-body radiation,
and (d) isoluminant green–red color maps

I was using a rainbow colour map to indicate “heat”, so, of course, I used red for the cool end, and blue for the hot end.  I was told by my then-manager that this was counter-intuitive.

Depends on the intuition, I suppose… 

note the direction of correlation between the temperature and the colour bar

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