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Journal of the Optical Society of America

Journal of the Optical Society of America

  • Vol. 53, Iss. 8 — Aug. 1, 1963
  • pp: 999–1002

Lines of Constant Correlated Color Temperature Based on MacAdam’s (u,υ) Uniform Chromaticity Transformation of the CIE Diagram

KENNETH L. KELLY  »View Author Affiliations

JOSA, Vol. 53, Issue 8, pp. 999-1002 (1963)

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The chromaticities of hot bodies (such as the filaments of incandescent lamps) and the various phases of daylight are often expressed on the color-temperature scale. Such chromaticities do not usually coincide precisely with those of the blackbody at any temperature, but are specified by giving the temperature of the blackbody yielding the nearest chromaticity match. Thus each chromaticity point near the Planckian locus is correlated with a chromaticity point on it, and the color temperature corresponding to the Planckian chromaticity is called the correlated color temperature. If the decision as to the nearest Planckian chromaticity is based on a uniform-chromaticity-scale (UCS) diagram, the chromaticity points correlated with each Planckian chromaticity fall on a straight line (isotemperature line) on the chromaticity diagram normal to the Planckian locus at that Planckian chromaticity. The UCS diagram proposed by MacAdam in 1937 and recommended in 1959 by the International Commission on Illumination (CIE) has been used here to define the isotemperature lines. Graphs showing the Planckian locus and the isotemperature lines both in the CIE (x,y)-diagram and in the MacAdam CIE (u,υ)-diagram are shown at every 10 microreciprocal degrees for all color temperatures higher than 1515°K.

KENNETH L. KELLY, "Lines of Constant Correlated Color Temperature Based on MacAdam’s (u,υ) Uniform Chromaticity Transformation of the CIE Diagram," J. Opt. Soc. Am. 53, 999-1002 (1963)

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  1. D. B. Judd, J. Opt. Soc. Am. 26, 421 (1936).
  2. R. Davis, J. Res. Natl. Bur. Std. 7, 659 (1931).
  3. O.S.A. Committee on Colorimetry, Te Science of Color (The T. Y. Crowell Company, New York, 1953), p. 303.
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  8. Compt. Rend. CIE 14e Brussels 1959, 107, 108.
  9. D. B. Judd, J. Opt. Soc. Am. 23, 359 (1933).
  10. H. G. W. Harding and T. Vickers, "Colours of Planckian Radiators Expressed on the CIE Trichromatic System for the Temperature Ranges 1500-10-9000°K and 0-1-660 Mired (C2= 14 380)," National Physical Laboratory, Teddington, Middlesex, England.
  11. A limited number of Xerox copies of Figs. 1 and 2 of this paper as well as of the 14 large-scale working graphs in x, y, are available on request. The large-scale graphs cover the same range of the Planckian locus as Figs. 1 and 2 but show a line of correlated color temperature for each microreciprocal degree.

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