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Journal of the Optical Society of America

Journal of the Optical Society of America

  • Vol. 57, Iss. 11 — Nov. 1, 1967
  • pp: 1319–1324

Chromatic Strength of Colors: Dominant Wavelength and Purity

RALPH M. EVANS and BONNIE K. SWENHOLT  »View Author Affiliations

JOSA, Vol. 57, Issue 11, pp. 1319-1324 (1967)

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A new visual threshold lying between the colors that appear to contain gray and those that appear fluorescent has been determined as a function of dominant wavelength at high purity on a white (7000 K) background. The function is found to be an approximately constant multiple of the previously known purity threshold; it is independent of purity and hence is named chromatic threshold. The value of the function for any given chromaticity is shown to be a measure of its chromatic strength in (a) neutralizing its complementary color, (b) producing Munsell Chroma. It is considered also in terms of the Hering—Johansson “Natural Color System,” where it appears to specify the “clear” series, and in terms of the Ostwald System.

RALPH M. EVANS and BONNIE K. SWENHOLT, "Chromatic Strength of Colors: Dominant Wavelength and Purity," J. Opt. Soc. Am. 57, 1319-1324 (1967)

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  1. Fluorence and fluorent are words coined by one of us2 to describe the appearance of fluorescence and the characteristic of so appearing, respectively. Use of distinct words is a reminder that physical fluorescence is not necessary to produce the appearance.
  2. R. M. Evans, J. Opt. Soc. Am. 49, 1049 (1959).
  3. D. Jameson and L. M. Hurvich, J. Opt. Soc. Am. 45, 546 (1955).
  4. R. H. Sinden, J. Opt. Soc. Am. 7, 1123 (1923).
  5. D. L. MacAdam, J. Opt. Soc. Am. 28, 103 (1938).
  6. T. Johansson, Rev. Opt. 28, 241 (1949).
  7. S. M. Newhall, D. Nickerson, and D. B. Judd, J. Opt. Soc. Am. 33, 385 (1943).
  8. G. Wyszecki and W. S. Stiles, Color Science (John Wiley & Sons, Inc., New york, 1967), p. 217.

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