Ishihara Colour Test Books
The Ishihara colour perception test for red-green color deficiencies.
The test consists of a number of colored plates containing 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 colour vision, and invisible, or difficult to see, to those with a red-green colour vision defect, or the other way around.
38, 24 and 14 Plate versions are available.