Dorothy Nickerson, "Disk Colorimetry; Including a Comparison of Methods for Computing Tristimulus Values for Certain Disks," J. Opt. Soc. Am. 25, 253-257 (1935)
This report provides a certain amount of information necessary for careful work with the disk method of colorimetry. Color temperatures are given for lamp and filter combinations of available instruments. Tristimulus specifications are given: for several Munsell papers under I. C. I. standard illuminants; for certain glossy papers under diffuse and 45° directional illumination; for colors made in the Munsell laboratory to match other colors when it was necessary to use different pigments; for several methods of computation, by summation for 5 and 10 mμ intervals, and by 10 and 30 selected ordinates; for curves differing slightly from each other; and for color differences significant in cotton grading. These last-mentioned figures are given as a basis for the comparison of the significance of all of the other differences.
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Tristimulus specifications of selected Munsell colors. Computations made from N.B.S. spectral reflectance measurements for diffuse illumination1 and from Judd tables2, at 10 mμ intervals. Values of z are omitted.
Except as otherwise noted.
J. Opt. Soc. Am. 23, 365 (1933).
These neutrals are a part of a special series. The notations given them by the Munsell Company are N 7.01/ and N 9.40/.
These papers are glossy surface papers made up specially for measuring tomato colors. The x and y values are given for measuring both under diffuse and 45° illumination. The results are very different, as might be expected.
Papers made specially to match Atlas colors. New pigments used. Matched for approximately 5700°K.
Table II
Tristimulus specifications compiled by different methods from the same spectral reflectance data.
Sample notation
Nat. Bur. Standards Spectral Reflectance Data, Report 431 fgh—70/34 Computations all made for I.C.I. Illuminant “C”
These computations were made from the values supplied in Bur. Standards report for the intervals ending in 0, and from values read from curves plotted from those figures for intervals ending in 5. The wavelength scale extended from 380 to 770 mμ.
These computations were made from values supplied in Bur. Standards report, for intervals ending in 10, from 380 to 770 mμ.
These computations were made from values read from curves plotted from data in Bur. Standards report. The curves referred to in 1 were used. The selected ordinates used were those which Professor Hardy was good enough to supply the writer. Readings were made from glass plates on which the ordinates were photographed as guides, the plates being supplied from drawings made in Professor Hardy’s laboratory. Checks were made from the wavelength tables where it seemed necessary.
The mid-ordinate of each group of three ordinates read off for the 30 ordinates was used in these computations.
Table III
Tristimulus specifications for spectral reflectance of dotted curves in Fig. 11 for I.C.I. Illuminant “C,” at 10 mμ intervals.
Hue notation
yw
x
y
R
0.1572
0.5517
0.3184
YR
.3367
.5025
.4137
YR
.4358
.4736
.4003
Y
.5668
.4578
.4779
GY
.4215
.3881
.4962
G
.2013
.2499
.4221
BG
.1332
.2244
.3227
B
.1081
.1981
.2429
PB
.0813
.1822
.1790
P
.1351
.2912
.1840
RP
.1638
.4101
.2518
These specifications are given for comparison to those for the solid line curves, given in the first 11 items of Table I.
Table IV
Tristimulus specifications for differences significant in color measurements of cotton made on a basis of disk mixtures.The x, y, z calculations were made by the addition of the xw, yw and zw values for the percentages of the disks exposed in making the color match. Calculations are for Illuminant “B” since it is nearest to the illuminant for the instrument on which the measurements were made.
Sample No.
Disk percentages
Munsell notations
Tristimulus specifications
YR
Y
N 9.4/
N 7/
Hue
Brilliance
Chroma
yw
x
y
1
10
10
41
39
1.00Y
8.08
1.70
0.6161
0.3680
0.3659
2
8
10
40
42
1.52Y
8.08
1.54
.6128
.3662
.3653
3
8
8
41
43
1.00Y
8.08
1.36
.6140
.3644
.3636
4
8
10
21
61
1.52Y
7.60
1.54
.5328
.3681
.3659
5
8
8
14
70
1.00Y
7.39
1.36
.5003
.3667
.3642
6
13
11
69
7
0.59Y
8.73
2.03
.7341
.3689
.3667
7
15
12
68
7
0.46Y
8.70
2.28
.7391
.3711
.3678
8
11
10
65
14
0.77Y
8.64
1.78
.7166
.3669
.3655
9
12
12
65
11
1.00Y
8.65
2.04
.7199
.3692
.3672
10
9
9
51
31
1.00Y
8.32
1.53
.6571
.3654
.3645
11
11
11
51
27
1.00Y
8.32
1.87
.6592
.3688
.3667
Tables (4)
Table I
Tristimulus specifications of selected Munsell colors. Computations made from N.B.S. spectral reflectance measurements for diffuse illumination1 and from Judd tables2, at 10 mμ intervals. Values of z are omitted.
Except as otherwise noted.
J. Opt. Soc. Am. 23, 365 (1933).
These neutrals are a part of a special series. The notations given them by the Munsell Company are N 7.01/ and N 9.40/.
These papers are glossy surface papers made up specially for measuring tomato colors. The x and y values are given for measuring both under diffuse and 45° illumination. The results are very different, as might be expected.
Papers made specially to match Atlas colors. New pigments used. Matched for approximately 5700°K.
Table II
Tristimulus specifications compiled by different methods from the same spectral reflectance data.
Sample notation
Nat. Bur. Standards Spectral Reflectance Data, Report 431 fgh—70/34 Computations all made for I.C.I. Illuminant “C”
These computations were made from the values supplied in Bur. Standards report for the intervals ending in 0, and from values read from curves plotted from those figures for intervals ending in 5. The wavelength scale extended from 380 to 770 mμ.
These computations were made from values supplied in Bur. Standards report, for intervals ending in 10, from 380 to 770 mμ.
These computations were made from values read from curves plotted from data in Bur. Standards report. The curves referred to in 1 were used. The selected ordinates used were those which Professor Hardy was good enough to supply the writer. Readings were made from glass plates on which the ordinates were photographed as guides, the plates being supplied from drawings made in Professor Hardy’s laboratory. Checks were made from the wavelength tables where it seemed necessary.
The mid-ordinate of each group of three ordinates read off for the 30 ordinates was used in these computations.
Table III
Tristimulus specifications for spectral reflectance of dotted curves in Fig. 11 for I.C.I. Illuminant “C,” at 10 mμ intervals.
Hue notation
yw
x
y
R
0.1572
0.5517
0.3184
YR
.3367
.5025
.4137
YR
.4358
.4736
.4003
Y
.5668
.4578
.4779
GY
.4215
.3881
.4962
G
.2013
.2499
.4221
BG
.1332
.2244
.3227
B
.1081
.1981
.2429
PB
.0813
.1822
.1790
P
.1351
.2912
.1840
RP
.1638
.4101
.2518
These specifications are given for comparison to those for the solid line curves, given in the first 11 items of Table I.
Table IV
Tristimulus specifications for differences significant in color measurements of cotton made on a basis of disk mixtures.The x, y, z calculations were made by the addition of the xw, yw and zw values for the percentages of the disks exposed in making the color match. Calculations are for Illuminant “B” since it is nearest to the illuminant for the instrument on which the measurements were made.
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