TITLE: What’s the etiquette on using diagrams that need color to be understood?
QUESTION [83 upvotes]: 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.

REPLY [3 votes]: Of course going through existing coloured diagrams and redesigning them in a monochrome (or grey-scale) colour scheme would be a lot of work, and depending on the complexity of the diagram the diagram may actually benefit from the use of colour.
But just because no other answer has mentioned the benefits of black & white (or greyscale) diagrams:

there are no issues for people with colour vision deficiency
many journals do not print in colour (unless you are prepared to pay for colour printing), so library copies will usually be black & white
some researchers will print the electronic version (or view it on an ebook reader) and having diagrams compatible with standard black & white laser printers is very convenient (not only for the printed journal copy).


Even though colours can be helpful, every diagram can be redesigned in black & white and there are several techniques for distinguishing elements as you would with colour:
lines

style (solid, dotted, dashed, ...)
thickness

objects

shape (circle, square, triangle, diamond, cross, ...)
filled vs. unfilled

areas

pattern (plain, striped, dotted, checkered, ...)
direction of pattern