Abstract

The relative luminance of a color at the threshold between gray content and apparent fluorescence (fluorence) is not much affected by the luminance of the surround but is greatly affected by its chromaticity. The results indicate that the continuum of color perceptions of a color stimulus seen against a variety of backgrounds is four dimensional. A new concept, “specific hue brilliance,” is shown to describe both the relationship of gray content to the purity of a color of a given dominant wavelength and the appearance of high-purity colors at constant luminance.

© 1969 Optical Society of America

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References

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  1. R. M. Evans and B. K. Swenholt, J. Opt. Soc. Am. 57, 1319 (1967).
    [Crossref] [PubMed]
  2. R. M. Evans and B. K. Swenholt, J. Opt. Soc. Am. 58, 580 (1968).
    [Crossref] [PubMed]
  3. Since no reference white is available in these situations, we have referred to the filters by nominal wavelength. Actually, the values plotted are λD for our 7000 K surround. At high purity, the reference white makes little difference.
  4. R. M. Evans, J. Opt. Soc. Am. 49, 1049 (1959).
    [Crossref]
  5. D. B. Judd, J. Opt. Soc. Am. 25, 24 (1935).
    [Crossref]
  6. D. Jameson and L. M. Hurvich, J. Opt. Soc. Am. 45, 546 (1955).
    [Crossref]
  7. D. L. MacAdam, J. Opt. Soc. Am. 28, 103 (1938). MacAdam defines moment as the product of the distance from the chromaticity of the color to the chromaticity of the white point times the mass of the color where mass is Y divided by y; i.e., mass is equal to X+Y+Z.
    [Crossref]
  8. It is well known that, at high purity, relative luminance does not describe lightness exactly. However, it has been a generally observed fact in all of this work that colors of lower relative luminance at G0 have looked darker than those of higher relative luminance.
  9. R. M. Evans, J. Opt. Soc. Am. 57, 279 (1967).
    [Crossref] [PubMed]
  10. It is not known whether this brilliance depends on perceived hue or on wavelength. We have used the words hue and brilliance because specific-wavelength brightness could be confused so easily with relative luminous efficiency.

1968 (1)

1967 (2)

1959 (1)

1955 (1)

1938 (1)

1935 (1)

J. Opt. Soc. Am. (7)

Other (3)

It is not known whether this brilliance depends on perceived hue or on wavelength. We have used the words hue and brilliance because specific-wavelength brightness could be confused so easily with relative luminous efficiency.

Since no reference white is available in these situations, we have referred to the filters by nominal wavelength. Actually, the values plotted are λD for our 7000 K surround. At high purity, the reference white makes little difference.

It is well known that, at high purity, relative luminance does not describe lightness exactly. However, it has been a generally observed fact in all of this work that colors of lower relative luminance at G0 have looked darker than those of higher relative luminance.

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Figures (7)

Fig. 1
Fig. 1

G0[log(LS/LB)] as a function of dominant wavelength with (X-X-X) a 7000 K surround and (0-0-0) a 3000 K surround both at 400 mL for observer BS.

Fig. 2
Fig. 2

G0[log(LS/LB)] as a function of nominal wavelength with three different highly chromatic surrounds. The surround luminance is 100 mL and the nominal wavelengths are: (X-X-X) 475 nm, (0-0-0) 528 nm, (Δ-Δ-Δ) 608 nm. Observer RME.

Fig. 3
Fig. 3

G0[log(LS/LB)] for three different nominal wavelengths of the central spot as a function of nominal wavelength of the surround. All surrounds were at a luminance of 100 mL. The solid line (X-X-X) is for 475 nm in the central spot. The broken line (0-0-0) is for 528 nm in the central spot. The results for 608 nm in the central spot are represented by the dotted (Δ⋯Δ⋯Δ) line. Observer BS.

Fig. 4
Fig. 4

Log(1/b) was determined from the assumed relation Lλ + LC = bLS in which Lλ is the luminance of a color at zero gray as determined by observer RME. LC is the luminance of the complementary color at zero gray determined by interpolation on the G0 – λD curve. LS is the luminance of the surround.

Fig. 5
Fig. 5

Log luminance at zero gray for λD = 608 nm as a function of pc with the surround at 100 mL and 7000 K. The lower solid line is logLλ calculated from the assumed relation SBλ(LλLλT) + LλT + LA = LS. The upper solid line is the calculated Lλ + LA, the straight line the luminance of the surround. X’s are experimentally determined values. Observer BS. SB was determined from the experimental data for the full filter pc = 1.0.

Fig. 6
Fig. 6

Same as Fig. 5 but for λD = 576 nm.

Fig. 7
Fig. 7

G0 vs λD corrected to pc = 1.0 for all filters by the equation used for Figs. 5 and 6 and original data of observer RME. The straight line is log(LS/LT) where LS is the luminance of the surround and LT is the achromatic threshold luminance in the conditions of observation.

Equations (7)

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G 0 - G 0 = log ( m λ / m c ) ,
( G 0 ) λ = log [ 1 + ( m λ / m c ) ] + log 1 / b λ .
S B ( L λ - L λ T ) + L λ T + L A = L S at G 0 ,
S B L λ + L A = L S at G 0 .
S B = ( L S / L λ ) + 1 - 1 / p c at G 0 .
G 0 = log [ p c ( S B - 1 ) + 1 ]
log L λ at G 0 = log [ p c L S p c ( S B - 1 ) - 1 ] .