@Mellivora @negative12dollarbill @fesshole
About one man in twelve has some form of colourblindness:
https://www.colourblindawareness.org/colour-blindness/
If Fessor can't make sense of the graphs in the paper then a good many men (and a smaller number of women) will have the same problem. As long as Fessor explains the reason for rejecting the paper, I think it's valid.
@CppGuy @Mellivora @negative12dollarbill @fesshole
The normal way for dealing with this level of error is to ask the author to fix it. That kind of feedback would be extremely valuable for people like early career researchers or people who have not been taught to consider accessibility.
I hope the OP does at least include this feedback in the rejection, but since its not usually considered a major fuckup, I fear this will get lost amoung whatever more serious error is given as a pretext. Indeed, if that error is not really a problem of would undermine the rest of the feedback.