The Cambridge test is easy to use for people with color blindness people or without blindness people. This test uses a familiar Landolt C stimulus, defined by the two test colors that are to be discriminated, on an achromatic background.
The test uses the fixed concept of introducing spatial and luminance noise into the stimulus, composed of grouped circles randomly varying in diameter and having no spatial structure.
Results are saved in ASCII (American Standard Code For Information Interchange) format and presented graphically as discrimination ellipses in CIELUV or CIE(x,y) color space.
The results are typical of a subject with normal color vision; in deficient subjects, the discrimination ellipses are significantly extended in the protan, deutan or Tritan chromaticity directions.