With 8 percent of men and nearly 1 percent of women suffering from color vision deficiency (CVD), using red and green together is a common problem when creating visualizations. People with strong CVD (“strong” meaning a more severe CVD) see both red and green as brown. People with weak CVD see bold red and green colors as different colors but still may have trouble distinguishing them if the red isn't red enough and the green isn't green enough.
This chapter provides different approaches for creating color-blind-friendly visualizations (even ones that use red and green).
Designing Color-Blind-Friendly Visualizations
Use a Color-Blind-Friendly Palette When Appropriate
One color used together in combination with another color is generally fine when one of them is not associated with CVD. For example, blue/orange is a common color-blind-friendly combination. Blue/red or blue/brown would also work. For the most common conditions of CVD, all of these work well, since blue would generally look blue to someone with CVD.
Figure 33.1 shows the Tableau color-blind–friendly palette designed by Maureen Stone. This palette works very well for the common cases of CVD. Notice how well this color palette works for the various comparisons of color under both protanopia and deuteranopia simulations.