Abstract

Estimation of chromaticity differences has been facilitated by the preparation of a standard mixture diagram showing by a group of ellipses the scales of perceptibility at the various parts of the diagram. The distances from the boundaries of the ellipses to their respective “centers” all correspond approximately to the same number (100) of “least perceptible differences.” The estimation of nearest color temperature has been facilitated by the preparation of a mixture diagram on which is shown a family of straight lines intersecting the Planckian locus; each straight line corresponds approximately to the locus of points representing stimuli of chromaticity more closely resembling that of the Planckian radiator at the intersection than that of any other Planckian radiator.

© 1936 Optical Society of America

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References

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  1. D. B. Judd, “The 1931 I.C.I. Standard Observer and Coordinate System for Colorimetry,” J. Opt. Soc. Am. 23, 359 (1933).
    [Crossref]
  2. D. B. Judd, “A Maxwell Triangle Yielding Uniform Chromaticity Scales,” Nat. Bur. Stand. J. Research 14, 41 (1935) RP756; also J. Opt. Soc. Am. 25, 24 (1935).
    [Crossref]
  3. See, for example, D. B. Judd, “A Method for Determining Whiteness of Paper,” Paper Trade Journal,  100, No. 21, TS40 (1935); also Tech. Assoc. Papers, Series XVIII, 392 (1935); and D. B. Judd, “A Method for Determining Whiteness of Paper, II,” Tech. Assoc. Papers, Series XIX, 359 (1936); also Paper Trade Journal 103, No. 8, TS38 (1936).
  4. For these terms and concepts, see R. Davis, “A Correlated Color Temperature for Illuminants,” Nat. Bur. Stand. J. Research 7, 659 (1931); RP365.
  5. Association of American Railroads, Signal Section Specification 69–35, Signal glasses (exclusive of hand lantern globes). Manual of Signal Section, AAR, Part 136 (1935).
  6. H. J. McNicholas, “Color and Spectral Transmittance of Vegetable Oils,” Nat. Bur. Stand. J. Research 15, 99 (1935); RP 815; also Oil & Soap 12, 167 (1935); see his Fig. 8.
    [Crossref]
  7. Fig. 2 is a reproduction of a figure previously used (see reference 1). Since that time a new color temperature scale has been adopted (see reference 9) and coincidentally the value of C2 used was changed from 14,350 to 14,320 micron degrees to conform with the International Temperature Scale. This change in C2 makes only 0.2 percent change in the temperature (or reciprocal temperature) and is too small to be shown in Fig. 2. For this reason the old diagram has been used. In Fig. 3, however, the change (about 0.8 μrd) could be easily seen.In Table II, the values of color temperature listed were taken from Davis’ paper in which the older value of 14,350 was used for C2.
  8. I. G. Priest, “A Proposed Scale for Use in Specifying the Chromaticity of Incandescent Illuminants and Various Phases of Daylight,” J. Opt. Soc. Am. 23, 41 (1933).
    [Crossref]
  9. H. T. Wensel, D. B. Judd, and Wm. F. Roester, “Establishment of a Scale of Color Temperature,” Nat. Bur. Stand. J. Research 12, 527 (1934); RP677.

1935 (3)

D. B. Judd, “A Maxwell Triangle Yielding Uniform Chromaticity Scales,” Nat. Bur. Stand. J. Research 14, 41 (1935) RP756; also J. Opt. Soc. Am. 25, 24 (1935).
[Crossref]

See, for example, D. B. Judd, “A Method for Determining Whiteness of Paper,” Paper Trade Journal,  100, No. 21, TS40 (1935); also Tech. Assoc. Papers, Series XVIII, 392 (1935); and D. B. Judd, “A Method for Determining Whiteness of Paper, II,” Tech. Assoc. Papers, Series XIX, 359 (1936); also Paper Trade Journal 103, No. 8, TS38 (1936).

H. J. McNicholas, “Color and Spectral Transmittance of Vegetable Oils,” Nat. Bur. Stand. J. Research 15, 99 (1935); RP 815; also Oil & Soap 12, 167 (1935); see his Fig. 8.
[Crossref]

1934 (1)

H. T. Wensel, D. B. Judd, and Wm. F. Roester, “Establishment of a Scale of Color Temperature,” Nat. Bur. Stand. J. Research 12, 527 (1934); RP677.

1933 (2)

1931 (1)

For these terms and concepts, see R. Davis, “A Correlated Color Temperature for Illuminants,” Nat. Bur. Stand. J. Research 7, 659 (1931); RP365.

Davis, R.

For these terms and concepts, see R. Davis, “A Correlated Color Temperature for Illuminants,” Nat. Bur. Stand. J. Research 7, 659 (1931); RP365.

Judd, D. B.

D. B. Judd, “A Maxwell Triangle Yielding Uniform Chromaticity Scales,” Nat. Bur. Stand. J. Research 14, 41 (1935) RP756; also J. Opt. Soc. Am. 25, 24 (1935).
[Crossref]

See, for example, D. B. Judd, “A Method for Determining Whiteness of Paper,” Paper Trade Journal,  100, No. 21, TS40 (1935); also Tech. Assoc. Papers, Series XVIII, 392 (1935); and D. B. Judd, “A Method for Determining Whiteness of Paper, II,” Tech. Assoc. Papers, Series XIX, 359 (1936); also Paper Trade Journal 103, No. 8, TS38 (1936).

H. T. Wensel, D. B. Judd, and Wm. F. Roester, “Establishment of a Scale of Color Temperature,” Nat. Bur. Stand. J. Research 12, 527 (1934); RP677.

D. B. Judd, “The 1931 I.C.I. Standard Observer and Coordinate System for Colorimetry,” J. Opt. Soc. Am. 23, 359 (1933).
[Crossref]

McNicholas, H. J.

H. J. McNicholas, “Color and Spectral Transmittance of Vegetable Oils,” Nat. Bur. Stand. J. Research 15, 99 (1935); RP 815; also Oil & Soap 12, 167 (1935); see his Fig. 8.
[Crossref]

Priest, I. G.

Roester, Wm. F.

H. T. Wensel, D. B. Judd, and Wm. F. Roester, “Establishment of a Scale of Color Temperature,” Nat. Bur. Stand. J. Research 12, 527 (1934); RP677.

Wensel, H. T.

H. T. Wensel, D. B. Judd, and Wm. F. Roester, “Establishment of a Scale of Color Temperature,” Nat. Bur. Stand. J. Research 12, 527 (1934); RP677.

J. Opt. Soc. Am. (2)

Nat. Bur. Stand. J. Research (4)

H. T. Wensel, D. B. Judd, and Wm. F. Roester, “Establishment of a Scale of Color Temperature,” Nat. Bur. Stand. J. Research 12, 527 (1934); RP677.

H. J. McNicholas, “Color and Spectral Transmittance of Vegetable Oils,” Nat. Bur. Stand. J. Research 15, 99 (1935); RP 815; also Oil & Soap 12, 167 (1935); see his Fig. 8.
[Crossref]

D. B. Judd, “A Maxwell Triangle Yielding Uniform Chromaticity Scales,” Nat. Bur. Stand. J. Research 14, 41 (1935) RP756; also J. Opt. Soc. Am. 25, 24 (1935).
[Crossref]

For these terms and concepts, see R. Davis, “A Correlated Color Temperature for Illuminants,” Nat. Bur. Stand. J. Research 7, 659 (1931); RP365.

Paper Trade Journal (1)

See, for example, D. B. Judd, “A Method for Determining Whiteness of Paper,” Paper Trade Journal,  100, No. 21, TS40 (1935); also Tech. Assoc. Papers, Series XVIII, 392 (1935); and D. B. Judd, “A Method for Determining Whiteness of Paper, II,” Tech. Assoc. Papers, Series XIX, 359 (1936); also Paper Trade Journal 103, No. 8, TS38 (1936).

Other (2)

Association of American Railroads, Signal Section Specification 69–35, Signal glasses (exclusive of hand lantern globes). Manual of Signal Section, AAR, Part 136 (1935).

Fig. 2 is a reproduction of a figure previously used (see reference 1). Since that time a new color temperature scale has been adopted (see reference 9) and coincidentally the value of C2 used was changed from 14,350 to 14,320 micron degrees to conform with the International Temperature Scale. This change in C2 makes only 0.2 percent change in the temperature (or reciprocal temperature) and is too small to be shown in Fig. 2. For this reason the old diagram has been used. In Fig. 3, however, the change (about 0.8 μrd) could be easily seen.In Table II, the values of color temperature listed were taken from Davis’ paper in which the older value of 14,350 was used for C2.

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Figures (3)

Fig. 1
Fig. 1

Perceptibility scales for the standard 1931 ICI colorimetric coordinate system. The distances from points on the boundary of each ellipse to the indicated point within it all correspond approximately to one hundred times the chromaticity difference just perceptible with certainty under moderately good observing conditions.

Fig. 2
Fig. 2

Iso-temperature lines shown on the standard 1931 ICI colorimetric coordinate system. Color stimuli specified on an iso-temperature line give closer chromaticity matches with the indicated Planckian color than with Planckian colors at neighboring color temperatures.

Fig. 3
Fig. 3

Iso-temperature lines shown for a small section of Fig. 2. This region includes the most-used portion of the color-temperature scale for incandescent lamps.

Tables (2)

Tables Icon

Table I Trilinear coordinates of Planckian stimuli and reciprocal of slopes of the iso-temperature lines as a function of reciprocal color temperature.

Tables Icon

Table II Comparison of conjunctive wave-length referring to nearest color temperature via the UCS system with that referring to Davis’ correlated color temperature.