I'm not entirely sure how this got past the Nature editors, since a lot of this is old hat, having been discussed widely, and for many years. The message is fi

I'm not entirely sure how this got past the Nature editors, since a lot of this is old hat, having been discussed widely, and for many years. The message is fine, as far as it goes. However, I would argue that perceptual neutrality is not the only measure of a colour scale. I hate jet as much as the next person, but I still do use the similar turbo scheme (which is less 'jagged' in perceptual space) when I teach. Why? Because it lets me show an image of a complex field (perhaps sea-surface temperature) and point to a spot of some value, and ask students to visually trace nearby spots of the same hue. It doesn't really matter if some students perceive the same hue for two different actual hues. So long as the neighbouring hues differ, the students can trace a local contour. I need that to explain certain topics. Using a colour scheme with just a couple of hues makes it very, very, difficult to trace contours. It's even worse when an image is projected onto a screen, in a classroom or at a meeting. Speaker: "See this slightly yellowish green on the colourbar, at 10C? Where is it in the map?" Audience: "I dunno, when's the next coffee break?" Essentially, colour maps with a lot of hues can make images into something like a contour diagram. This can help, because some fields are so ragged that contours are difficult to understand. Sometimes, a linear mapping between data values and the perceived colour is the end goal. Other times, not.