The use of master color samples is widespread in industry as a means of color control and color standardization. The precision to which the standards have to be maintained varies with the industry, but in the case, for example, of automobiles, a very high consistency of color matching is demanded. Matches are most frequently judged by eye and color measuring techniques often find little favor. The extent to which physical instrumentation can and should replace visual inspection is debatable, but if analogy with the measurement of length or light is legitimate, then it would seem desirable to provide sets of permanent reference standards covering a wide range of colors and specified to the highest possible accuracy.
W. D. WRIGHT, "Color Standards in Commerce and Industry," J. Opt. Soc. Am. 49, 384-388 (1959)