Ishihara Books

The Ishihara Color Test is an example of a color perception test for red-green color deficiencies. The test consists of colored plates, called Ishihara plates, each of which contains a circle of dots appearing randomized in color and size. Within the pattern are dots which form a number or shape clearly visible to those with normal color vision, and invisible, or difficult to see, to those with a red-green color vision defect, or the other way around. The plates make up several different test designs.