Color Discrimination, Color Conspicuity, and Visual Search for CRT Displays

A visual search task, such as the detection, discrimination, and separation of a target in a display, requires a display layout that has been properly designed, taking account of color and luminance discrimination abilities. Previous investigations on visual search, however, have focused on fundamental analysis rather than practical application. This paper describes (1) color matching properties from the viewpoint of the practical use of complex backgrounds, and (2) conspicuity expressed in quantitative terms of visual search times and the color differences between the target and the background. Such an expression could help determine the maximum number of colors that could be simultaneously presented to get the best conspicuity in a visual display. This paper shows that complex backgrounds decrease the precision of color matching considerably. Color and luminance discrimination data obtained in earlier fundamental investigations may therefore not be applicable to practical applications. This paper also shows that because the presence of a large number of colors surrounding a target increases the noise level and slows a visual search, the maximum number of colors that can be simultaneously shown on a visual display ranges (depending on the purpose of the display) from 15 to 30.