Emilio Segrè Visual Archives, Am, Inst. Physics, 2019
Deane Brewster Judd was an American physicist who contributed to the fields of colorimetry, color discrimination, color order, and color vision. Born in South Hadley Falls, Massachusetts on 15 November 1900, he attended Ohio State University and received an A.B. in 1922 and an M.A. in 1923 [1]. He completed his Ph.D. in physics at Cornell University in 1926 with a dissertation on a quantitative investigation of the Purkinje afterimage. Judd demonstrated pioneering efforts in the use of psychology in colorimetric studies. He was a Munsell Research Associate in colorimetry at the National Bureau of Standards (NBS) in Washington in 1926.
In 1927, Judd joined the NBS, where he remained until his retirement in 1969 and subsequently continued as a guest worker. He was the USA’s representative in colorimetry at eight meetings of the International Commission on Illumination (CIE) from 1931 to 1967 and thereby a key force in the development of the CIE standard system of colorimetry, e.g., 1931 and 1964 standard observers, standard illuminants B and C, daylight illuminants like D65, and definition of colorimetric purity [2]. Largely responsible for coining the term “psychophysics,” he wrestled throughout his career with the relationship between color stimuli and color perception.
69.1 Colorimetric System and Color Difference
Judd introduced the concept of keeping luminosity and chromaticness separate in the CIE system. He was active in the colorimetric definition of color temperature and introduced the CIE colorimetric system to US industries. Together with D. L. MacAdam and G. Wyszecki, in 1964, he used principal component analysis to show that natural daylights are largely composed of three components from which daylights at any correlated color temperature can be defined (CIE method of calculating D-illuminants) [3].
In a series of papers in the 1930 s, Judd represented then available color scaling data first into a chromaticity diagram based on color-matching functions introduced by the Optical Society of America in 1922, then represented the resulting diagram in a Maxwell-type primary triangle, and finally embedding unit difference ellipses into the CIE chromaticity diagram. This work became the basis for the CIE u,v color diagram in 1960, slightly modified in the 1976 CIELUV color space. In 1939, he was instrumental in developing the NBS color-difference formula. When in 1947, at the suggestion of the U.S. National Research Council, the Optical Society of America (OSA) undertook to develop a perceptually uniform color space Judd became its chairman and remained in that position until 1968, when D. L. MacAdam assumed the chairmanship, with results published in 1974. One of the key findings was “that strictly uniform color scales of all kinds are not homologous with Euclidean space” to which Judd proposed a solution implemented in the OSA uniform color space [2].
- 3.
Miscellaneous
At NBS, Judd investigated impaired color vision, whiteness measurement of paper, opacity, and color stimulus measurement and developed a flattery index for artificial light sources. In 1951, he proposed a modification of the CIE 1924 luminous efficiency function V(λ) below 460 nm that became known as Judd-modified V(λ), not implemented in the CIE system but used in some vision research work [8]. In addition to his positions at the CIE, Judd was president of the Optical Society of America from 1953 to 1955 and of the Inter-Society Color Council from 1940 to 1944. He was president of the Board of Trustees of the Munsell Color Foundation from 1942 to 1972.
In his homage, the International Color Association, AIC, instituted its Judd Award, a prize that since 1975 is bestowed every two years to persons who have made important contributions in color research.
Judd was the author of one book [9] and more than 200 articles, 57 of which were reprinted as a volume by the NBS [2].