Page:Journal of the Optical Society of America, volume 30, number 12.pdf/4

DECEMBER, 1940

N obvious purpose is served by arranging this series of five papers on the Munsell Color System together as a unit. The various steps in the development of the ideas of the originator,, may in this way be presented together with the technical data resulting from each step so that for the first time it is possible for a reader to trace this development in complete detail. But there is a second, less obvious, though no less important purpose served by this series of papers. It arises from the fact that Mr. Munsell's original idea for color specification had two aspects: First, that the color notation should indicate color as perceived by the observer; second, that the assignment of the notations should be based upon an accurately reproducible system of measurement. That is, the ideal color notation should conform to a purely psychological requirement and at the same time enjoy a rigorous psychophysical definition.

It is a common first impression of many students of colorimetry that this double requirement is easy to meet; in fact, it is often erroneously supposed by them that there is no need for the distinction between psychological and psychophysical systems. More thorough consideration reveals this error and often gives rise to the opinion that the two kinds of system are so utterly different in their concepts that there is no possibility of correspondence between them. To one who holds this opinion, Mr. Munsell's original idea seems to be based upon ignorance and impossible to fulfill.

There are possible, however, many psychophysical color systems. Some of them, such as the tristimulus system, yield variables having no obvious relation to the psychological attributes of color as perceived by the observer. Others, such as the dominant wave-length and purity system, yield variables having some degree of correspondence to them. Mr. Munsell knew well that the search for a psychophysical color system whose notation should correspond with what an observer sees is far from hopeless because he discovered a psychophysical system which fulfills this condition to a. surprising degree, better than any yet found of comparable simplicity.

The second purpose of arranging these papers into a series is, therefore, to bring out the much misunderstood relations and distinctions between psychological and psychophysical color systems. The second paper of this series, that by and, analyzes the psychophysical color system discovered by A. H. Munsell. The third paper, that by K. S. Gibson and D. Nickerson, shows the degree to which the color standards of the 1915  accord with this psychophysical color system. The fourth paper, that by J. J. Glenn and J. T. Killian, defines psychophysically the color system previously defined only by the material color standards of the 1929 Munsell Book of Color. The final paper of the series, "," by S. M. Newhall, Chairman, presents extensive data on which is to be based a psychophysical color system intended to fulfill as closely as possible the psychological ideal of A. H. Munsell. , Associate Editor