The Ishihara Colour Test is an example of a colour perception test for ‘red-green’ colour deficiencies.
The test consists of 65 images in a book 210 mm long x 145 mm high.
Each plate contains a circle of dots of random size and colour.
Within the circle of dots a number or shape is clearly visible to those with normal colour vision, and invisible, or difficult to see by those with a red-green defect.
(Note: Use for images only, Chinese print)