[Math] What’s the etiquette on using diagrams that need color to be understood

mathematical-writingresearchsoft-question

I’m working on a paper that makes heavy use of colorful diagrams to supplement the text. For most of these it would probably not be possible to create grayscale versions that convey the same information as effectively. I’m a bit worried about this because (1) I imagine that some people like to print out papers to read them but these people might not want/be able to print in color, and (2) some readers may be colorblind.

What are the expectations on an author in my situation? Will it be considered rude to leave as-is, so long as the diagrams are not technically necessary to verify the arguments? Am I expected to include a description in the captions (“this region is red, this region is blue…”)? Or most stringently, would I be expected to post a “colorblind version” somewhere that tries to recreate the diagrams in grayscale as best as I can?

I’m interested in all opinions, but especially those of people who would have trouble with color for whatever reason.

Best Answer

The concern with color figures for grey scale printing is less of an issue these days, when pretty much all displays are in color, so the reader can always check which color is which even if the document is printed in grayscale. (Many journals no longer insist that the figures should display well when printed in grayscale.)

The issue with color blind readers is more substantial. Best practice ("etiquette") is to

  • Avoid ambiguous color combinations: green & brown, blue & purple, green & blue, light green & yellow, blue & grey, green & grey, green & black;
  • Use a high enough contrast, which most color blind people can still distinguish.
  • Use textures instead of / in addition to colors;
  • Add a label or graphical element to distinguish different colors.

Here is a color-blind safe palette:

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