Abstract

An experiment was conducted in which observers adjusted the luminance of a 2856 K white comparison source to appear equally as bright as a red, yellow, or yellowish-green LED alpha-numeric source. Although the present CIE photometric system predicts brightness-luminance ratios of 1.0, the ratios obtained in this experiment, for the mean observer, were 1.13 for the yellowish-green, 1.28 for the yellow, and 2.54 for the red. These results demonstrate that there can be substantial differences between photometric luminance based on the V(λ) function and brightness as perceived visually.

© 1978 Optical Society of America

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References

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  1. G. Wyszecki and W. S. Stiles, Color Science (Wiley, New York, 1967).
  2. CIE publication No. 17, International Lighting Vocabulary, 3rd ed. (1970).
  3. Y. Le Grand, Light, Colour and Vision, 2nd ed. (Chapman and Hall, London, 1968).
  4. D. L. MacAdam, “Loci of constant hue and brightness determined with various surrounding colors,” J. Opt. Soc. Am. 40, 589–595 (1950).
    [Crossref]
  5. R. E. Harrington, “Effect of color temperature on apparent brightness,” J. Opt. Soc. Am. 44, 113–116 (1954).
    [Crossref] [PubMed]
  6. A. Chapanis and R. M. Halsey, “Luminance of equally bright colors,” J. Opt. Soc. Am. 45, 1–6 (1955).
    [Crossref] [PubMed]
  7. W. E. K. Middleton and H. S. T. Gottfried, “Apparent Intensities of Colored Signal Lights,” Illum. Eng. 52, 192–196 (1957).
  8. E.J. Breneman, “Dependence of luminance required for constant brightness upon chromaticity and chromatic adaptation, J. Opt. Soc. Am. 48, 228–232 (1958).
    [Crossref]
  9. C. L. Sanders and G. Wyszecki, “Correlate for lightness in terms of CIE tristimulus values. I.,” J. Opt. Soc. Am. 47, 398–404 (1957).
    [Crossref]
  10. G. Wyszecki and C. L. Sanders, “Correlate for lightness in terms of CIE tristimulus values. II.,” J. Opt. Soc. Am. 47, 840–842 (1957).
    [Crossref] [PubMed]
  11. C. L. Sanders and G. Wyszecki, “L/Y ratios in terms of CIE-chromaticity coordinates,” J. Opt. Soc. Am. 48, 389–392 (1958).
    [Crossref]
  12. G. Wyszecki, “Correlate for lightness in terms of CIE chromaticity coordinates and luminance reflectance,” J. Opt. Soc. Am. 57, 254–257 (1967).
    [Crossref] [PubMed]
  13. C. L. Sanders and G. Wyszecki, “Correlate for Brightness in Terms of CIE Color Matching Data,” Compte Rendu, CIE, Vienna, 221–230 (1963).
  14. P. Kowaliski, “Equivalent luminances of colors,” J. Opt. Soc. Am. 59, 125–130 (1969).
    [Crossref]
  15. D. H. Alman, “Errors of the Standard Photometric System When Measuring the Brightness of General Illumination Light Sources,” J. Illum. Eng. Soc. 7, 55–62 (1977).
  16. NBS and NRC-Canada are involved in a cooperative effort to compare photometric luminance with perceived brightness. The present work is a companion project to the work by Alman at NRC. Future work at NRC will use sources 2° or larger, while NBS will concentrate on sources 1° or smaller.
  17. A. C. Wall, “The Photometry of Colored Light,” Illum. Eng. 62, 239 (1967).
  18. FASCAL, Optical Radiation News No. 18, Natl. Bur. Stand., November1976.
  19. H. E. Ives, “Studies in the Photometry of Lights of Different Colors. I. Spectral Luminosity Curves Obtained by the Equality of Brightness Photometer and the Flicker Photometer Under Similar Conditions,” Philos. Mag. 24, No. 6, 149 (1912).
  20. W. W. Coblentz and W. B. Emerson, “Relative Sensibility of the Average Eye to Light of Different Colors and Some Practical Applications to Radiation Problems,” Bull. Bur. Stand. 14, 161 (1918).

1977 (1)

D. H. Alman, “Errors of the Standard Photometric System When Measuring the Brightness of General Illumination Light Sources,” J. Illum. Eng. Soc. 7, 55–62 (1977).

1976 (1)

FASCAL, Optical Radiation News No. 18, Natl. Bur. Stand., November1976.

1969 (1)

1967 (2)

1958 (2)

1957 (3)

1955 (1)

1954 (1)

1950 (1)

1918 (1)

W. W. Coblentz and W. B. Emerson, “Relative Sensibility of the Average Eye to Light of Different Colors and Some Practical Applications to Radiation Problems,” Bull. Bur. Stand. 14, 161 (1918).

1912 (1)

H. E. Ives, “Studies in the Photometry of Lights of Different Colors. I. Spectral Luminosity Curves Obtained by the Equality of Brightness Photometer and the Flicker Photometer Under Similar Conditions,” Philos. Mag. 24, No. 6, 149 (1912).

Alman, D. H.

D. H. Alman, “Errors of the Standard Photometric System When Measuring the Brightness of General Illumination Light Sources,” J. Illum. Eng. Soc. 7, 55–62 (1977).

Breneman, E.J.

Chapanis, A.

Coblentz, W. W.

W. W. Coblentz and W. B. Emerson, “Relative Sensibility of the Average Eye to Light of Different Colors and Some Practical Applications to Radiation Problems,” Bull. Bur. Stand. 14, 161 (1918).

Emerson, W. B.

W. W. Coblentz and W. B. Emerson, “Relative Sensibility of the Average Eye to Light of Different Colors and Some Practical Applications to Radiation Problems,” Bull. Bur. Stand. 14, 161 (1918).

Gottfried, H. S. T.

W. E. K. Middleton and H. S. T. Gottfried, “Apparent Intensities of Colored Signal Lights,” Illum. Eng. 52, 192–196 (1957).

Halsey, R. M.

Harrington, R. E.

Ives, H. E.

H. E. Ives, “Studies in the Photometry of Lights of Different Colors. I. Spectral Luminosity Curves Obtained by the Equality of Brightness Photometer and the Flicker Photometer Under Similar Conditions,” Philos. Mag. 24, No. 6, 149 (1912).

Kowaliski, P.

Le Grand, Y.

Y. Le Grand, Light, Colour and Vision, 2nd ed. (Chapman and Hall, London, 1968).

MacAdam, D. L.

Middleton, W. E. K.

W. E. K. Middleton and H. S. T. Gottfried, “Apparent Intensities of Colored Signal Lights,” Illum. Eng. 52, 192–196 (1957).

Sanders, C. L.

Stiles, W. S.

G. Wyszecki and W. S. Stiles, Color Science (Wiley, New York, 1967).

Wall, A. C.

A. C. Wall, “The Photometry of Colored Light,” Illum. Eng. 62, 239 (1967).

Wyszecki, G.

Bull. Bur. Stand. (1)

W. W. Coblentz and W. B. Emerson, “Relative Sensibility of the Average Eye to Light of Different Colors and Some Practical Applications to Radiation Problems,” Bull. Bur. Stand. 14, 161 (1918).

Illum. Eng. (2)

A. C. Wall, “The Photometry of Colored Light,” Illum. Eng. 62, 239 (1967).

W. E. K. Middleton and H. S. T. Gottfried, “Apparent Intensities of Colored Signal Lights,” Illum. Eng. 52, 192–196 (1957).

J. Illum. Eng. Soc. (1)

D. H. Alman, “Errors of the Standard Photometric System When Measuring the Brightness of General Illumination Light Sources,” J. Illum. Eng. Soc. 7, 55–62 (1977).

J. Opt. Soc. Am. (9)

Natl. Bur. Stand. (1)

FASCAL, Optical Radiation News No. 18, Natl. Bur. Stand., November1976.

Philos. Mag. (1)

H. E. Ives, “Studies in the Photometry of Lights of Different Colors. I. Spectral Luminosity Curves Obtained by the Equality of Brightness Photometer and the Flicker Photometer Under Similar Conditions,” Philos. Mag. 24, No. 6, 149 (1912).

Other (5)

NBS and NRC-Canada are involved in a cooperative effort to compare photometric luminance with perceived brightness. The present work is a companion project to the work by Alman at NRC. Future work at NRC will use sources 2° or larger, while NBS will concentrate on sources 1° or smaller.

G. Wyszecki and W. S. Stiles, Color Science (Wiley, New York, 1967).

CIE publication No. 17, International Lighting Vocabulary, 3rd ed. (1970).

Y. Le Grand, Light, Colour and Vision, 2nd ed. (Chapman and Hall, London, 1968).

C. L. Sanders and G. Wyszecki, “Correlate for Brightness in Terms of CIE Color Matching Data,” Compte Rendu, CIE, Vienna, 221–230 (1963).

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Figures (3)

FIG. 1
FIG. 1

Spectral radiance profile of red LED alpha-numeric.

FIG. 2
FIG. 2

Relative luminance distribution scan along the length of the horizontal segment of the H pattern displayed by the red LED alpha-numeric. Spectroradiometry was employed to assign a luminance of 675 cd/m2 to an area 0.6 × 0.8 mm in the middle of the segment.

FIG. 3
FIG. 3

Schematic diagram of the stimuli-presenting apparatus. The optical components are labeled as follows: test lamp (TL), front surface mirror (M), filter (F), stencil (S), integrating sphere (SP), comparison lamp (CL), and neutral density wedge (W).

Tables (2)

Tables Icon

TABLE I Chromaticity coordinates and average luminance of the LED alpha-numerics.

Tables Icon

TABLE II Brightness to luminance (B/L) ratios for each observer, mean B/L ratios for each color, and the standard deviation.

Equations (1)

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L v = K m V ( λ ) L ( λ ) d λ ,