How many colors can the eye distinguish?
There are several ways to answer this question. The most sensitive method is to place colors side-by-side and ask whether they appear the same or different. However, there are too many possible color combinations to determine the actual number of distinguishable colors by direct experiment. Several sources (Halsey and Chapanis, 1951; Kaiser and Boynton, 1989) have used the limited existing data combined with some theory to estimate that under best conditions, the eye can distinguish one million colors – combinations of hue, saturation and brightness. Other estimates, however, put the number as high as 7 million (Chapanis, 1954). In less optimized conditions, the number of discriminable colors is much smaller. If the color samples are separated in space or in time, the number of distinguishable colors falls precipitously. The number also falls with smaller size, shorter viewing time, lower illuminance, and several other factors. In electronic screens, CRT, plasma, LCD, etc., the technol
