Abstract

Chromaticity shifts on the RUCS scale, for 20% increase in intensity in a single band 0.01 μ wide, were computed for deluxe cool-white and warm-white fluorescent lamps and ten hypothetical pigments with color points almost uniformly spaced about that of the illuminant. At each wavelength, the color shift of the most sensitive pigment was taken as a measure of the importance of the spectral flux per 100 A. Seven bands of roughly equal importance in rating cool-white lamps have division points at 0.44, 0.49, 0.53, 0.56, 0.60, and 0.62 μ. For warm-white lamps, the second division point listed above should be omitted. The outer limits of the end bands should be 0.42 and 0.67 μ for ratings based on unweighted energy flux. For comparisons of dissimilar spectral curves, one should weight energy flux within each band in proportion to the maximum shift on the RUCS scale, per unit increment of spectral flux. This weighting factor has maxima at approximately 0.445, 0.53, and 0.615 μ and minima at 0.49 and 0.57–0.58 μ.

Importance in rating deluxe cool-white lamps is only 5 and 8, respectively (average=100) for Bouma’s end bands, 51–195 for the other six, and 73–136 for Kruithof’s 7-band system.

© 1957 Optical Society of America

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References

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  1. For spectral curves, see pp. 256–7 of The Science of Color, by Colorimetry Committee, Optical Society of America (Thomas Y. Crowell Company, New York, 1953).
  2. Barr, Clark, and Hessler, Illum. Eng. 47, 649 (1952).
  3. P. J. Bouma, Proc. 1939 CIE meeting, Vol. 2, p. 57.
  4. A. A. Kruithof, Proc. 1951 CIE meeting, Vol. 2, paper V.
  5. Lines 8 and 12 of Table I, reference 3.
  6. C. W. Jerome and D. B. Judd, Illum. Eng. 48, 259 (1953). W. Harrison, Light and Lighting148 (April, 1951).
  7. For example, see paper by J. L. Saunderson and B. I. Milner, J. Opt. Soc. Am. 36, 36 (1946).
    [Crossref] [PubMed]
  8. W. S. Stiles, Optica Acta (Paris) 2, 168 (1955).
    [Crossref]

1955 (1)

W. S. Stiles, Optica Acta (Paris) 2, 168 (1955).
[Crossref]

1953 (1)

C. W. Jerome and D. B. Judd, Illum. Eng. 48, 259 (1953). W. Harrison, Light and Lighting148 (April, 1951).

1952 (1)

Barr, Clark, and Hessler, Illum. Eng. 47, 649 (1952).

1946 (1)

Barr,

Barr, Clark, and Hessler, Illum. Eng. 47, 649 (1952).

Bouma, P. J.

P. J. Bouma, Proc. 1939 CIE meeting, Vol. 2, p. 57.

Clark,

Barr, Clark, and Hessler, Illum. Eng. 47, 649 (1952).

Hessler,

Barr, Clark, and Hessler, Illum. Eng. 47, 649 (1952).

Jerome, C. W.

C. W. Jerome and D. B. Judd, Illum. Eng. 48, 259 (1953). W. Harrison, Light and Lighting148 (April, 1951).

Judd, D. B.

C. W. Jerome and D. B. Judd, Illum. Eng. 48, 259 (1953). W. Harrison, Light and Lighting148 (April, 1951).

Kruithof, A. A.

A. A. Kruithof, Proc. 1951 CIE meeting, Vol. 2, paper V.

Milner, B. I.

Saunderson, J. L.

Stiles, W. S.

W. S. Stiles, Optica Acta (Paris) 2, 168 (1955).
[Crossref]

Illum. Eng. (2)

Barr, Clark, and Hessler, Illum. Eng. 47, 649 (1952).

C. W. Jerome and D. B. Judd, Illum. Eng. 48, 259 (1953). W. Harrison, Light and Lighting148 (April, 1951).

J. Opt. Soc. Am. (1)

Optica Acta (Paris) (1)

W. S. Stiles, Optica Acta (Paris) 2, 168 (1955).
[Crossref]

Other (4)

For spectral curves, see pp. 256–7 of The Science of Color, by Colorimetry Committee, Optical Society of America (Thomas Y. Crowell Company, New York, 1953).

P. J. Bouma, Proc. 1939 CIE meeting, Vol. 2, p. 57.

A. A. Kruithof, Proc. 1951 CIE meeting, Vol. 2, paper V.

Lines 8 and 12 of Table I, reference 3.

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Figures (7)

Fig. 1
Fig. 1

RUCS diagram showing chromaticity of test “samples” with 40 w deluxe cool-white fluorescent lamp as illuminant. + Lamp alone. ○ Hypothetical pigments.

Fig. 2
Fig. 2

Spectral reflectance curves for two of the test pigments. (See corresponding points in Fig. 1 for chromaticity.)

Fig. 3
Fig. 3

Color shift used as a measure of the effectiveness for color-rendition, of the spectral flux from a deluxe cool-white fluorescent lamp. Vertical lines dividing area under curve into five equal parts indicate ideal division points for a 5-band system.

Fig. 4
Fig. 4

Spectral distribution for the deluxe cool-white lamp.

Fig. 5
Fig. 5

Displacement on RUCS diagram of color points for test pigments, per unit increment of spectral flux, with deluxe cool-white lamp as illuminant. At each wavelength, only the curves for the most sensitive pigments are shown.

Fig. 6
Fig. 6

Weighting factors for spectral flux. (Envelope of curves in Fig. 5, and corresponding one for deluxe warm-white lamp.)—For cool-white lamps;– –for warm-white lamps.

Fig. 7
Fig. 7

Band limits and relative importance of each band.

Tables (2)

Tables Icon

Table I Band system ratings, with and without weighting, for various fluorescent lamps. (Ratings are differences expressed as percent of total flux in all of the bands.)

Tables Icon

Table II Single number ratings for fluorescent lamps. (100 minus sum of absolute values of ratings in table 1.)