Colorblindness is not a total loss of color vision. Colorblind people can recognize a wide ranges of colors. But certain ranges of colors are hard to distinguish.
The frequency of colorblindness is fairly high. One in twelve Caucasian (8%), one in 20 Asian (5%), and one in 25 African (4%) males are so-called “red-green” colorblind. It is commoner than AB blood group.
3(+1) principles of Color Universal Design
1.Choose color schemes that can be easily identified by people with all types of color vision, in consideration with the actual lighting conditions and usage environment.
2. Use not only different colors but also a combination of different shapes, positions, line types and coloring patterns, to ensure that information is conveyed to all users including those who cannot distinguish differences in color.
3.Clearly state color names where users are expected to use color names in communication.
4. Moreover, aim for visually friendly and beautiful designs.