An experiment employed the Shademaster Computer Aided Design system to assess the ability of the CMC formula (devised by the COlur Measurement Commitee of the Society of Dyers and Colourists) to measure small visual color differences. the researchers asked a group of 10 observers to judge differences in the hue, chroma, and lightness of various color difference pairs that were projected on a CRT monitor. Each color difference pair appeared in the form of a divided tile. Nine colors were used: blue, purple, pale blue, green, yellow, orange, pink, red, and brown. The researchers compared the results with measurements from a Bentham telespectroradiometer and with data from a method based on the reverse transformation of RGB to CIE coordinates. The results showed that the observers were able to accurately detect small differences between colors projected on a CRT monitor. However, the presence of statistically significant anomalies in the data caused the researchers to doubt the validity of treating color differences on a three dimensional Euclidean scale. Nevertheless, they concluded that the CMC formula offers a 'reasonable' scale for small visual color differences. 26 refs.