When designing scientific graphics, one key choice is about which colour scale to use (something discussed in several previous posts). The animated graphic below is a simulation of how an image would look to someone who is colour blind (a few percent of men).
Watch how the pattern emerges as the level of simulated colour blindness is reduced:
Simple conclusion: try to avoid using shades of red and green in the same figure to maximise the accessibility of your graphics. Sadly, some scientific journals are still publishing figures which are impossible to read for those who are colour blind. Join the campaign!
[Similar Ishihara images are often used to test for colour blindness. Thanks to Doug McNeall for useful comments on an earlier version of the graphic.]