The Neural Control of Vision
J. The Processing of Color

The next two figures show another, more recent test that has been developed for assessing deficits in color vision that has two significant advantages. The first is that the degree of chrominance information can be readily manipulated which allows for determining the magnitude of the color deficit. This is important because there is a wide range of deficit magnitudes in the population. The second advantage is that the dynamic nature of the presentation, in which various segments of the display are randomly varied in contrast, minimize the ability to utilize any luminance information for visual discrimination. This is important because the distribution of the various cone types is not uniform in various regions of the retina, as a result of which even in normal subjects the isoluminance points are not uniform throughout the visual field.