1: unambiguous both to colorblinds and non-colorblinds,
2: with vivid colors so that color names are easy to identify,
3: can be printable with similar color both on screen and when printed.
- For red, vermilion is used since it is recognizable also to protanopes.
- Colors between yellow and green are all avoided, since they are indistinguishable with yellow and orange.
- For green, bluish green is chosen so that it won’t be confused with red or brown.
- Since violet is close to blue and appear the same to colorblinds, reddish purple is chosen.
- Between vermilion and yellow, three colors with different apparent intensity is selected.
- Sky blue and blue are chosen so that they are distinguishable with there difference in brightness and saturation.
- Even for non-coloblinds, thin lines and small characters in blue and yellow are hard read. For thin lines and small objects, use darker blue and orange is preferable to sky blue and yellow.
When combining colors from this pallet,
- Use “warm” and “cool” colors alternatively.
- When using two warm colors or two cool colors, put distinct differences in brightness or saturation.
- Avoid combination of colors with low saturation or low brightness.
Source cited from : http://jfly.iam.u-tokyo.ac.jp/color/, Research at University of Tokyo