The Neural Control of Vision
J. The Processing of Color

The basics of the procedures for this test are shown in the figure below, described for luminance cues. The display consists of two sets of squares. One set defines the background and the other the letters as can readily be seen. The background set has, in this case, squares with four contrast levels randomly arranged. The set defining the letters also has four contrast levels but they all have higher than the background elements. The display is dynamic as can be seen when you click on the figure. As a result the luminance level of each square varies randomly using the same four sets for both the background and the letters.