Three new sets of color-matching experiments have been made by three observers binocularly viewing a bipartite field (each half subtending 3°) of a three-primary colorimeter. Each set of color-matching data refers to 28 test colors scattered over the chromaticity gamut provided by the colorimeter. The luminance of each test color was 12 cd · m−2; the white surround (subtending 40°) was maintained at 6 cd · m−2. The elliptical cross sections (for Y = const) of the observed color-matching ellipsoids are compared with results previously published by MacAdam, and Brown and MacAdam. In view of the inherent experimental uncertainties of data of this kind, the new color-matching ellipses correlate well with those obtained by Brown, and Brown and MacAdam, but show significant deviations from those obtained by MacAdam’s observer P. G. Nutting, Jr. The discrepancies are puzzling. A note of caution is added with regard to the usefulness of color-matching ellipses in testing line elements. A set of color-matching ellipses can reveal only little of the visual mechanism that governs the precision of color matching and its assumed direct correlation with judging small color differences. It appears that fundamentally different line elements can reproduce almost equally well a given set of color-matching ellipses.
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The third coordinate l0 of the color center is constant for all 28 test colors; l0 = 0.2 log10Y0 = 0.2156, corresponding to a luminance L0 ≡ Y0 = 12 cd · m−2.
Supplementary to Table I. The data given in row M correspond to a mean ellipsoid and its cross section for the respective test color; these data are identical to those given in Table 1.
Table III
Color-matching ellipses of observers PGN, WSS, and FMC.a
Color center
No.
Obs.
x0
y0
θ(deg)
a(·103)
b(·103)
a/b
log10A
1
PGN
0.160
0.057
62.5
0.85
0.35
2.43
−6.029
WSS
85.5
2.4
1.4
1.71
−4.977
FMC
76.4
1.1
0.34
3.20
−5.926
2
PGN
0.187
0.118
77.0
2.2
0.55
4.00
−5.420
WSS
76.8
6.3
2.9
2.17
−4.241
FMC
72.0
2.0
0.53
3.88
−5.469
3
PGN
0.253
0.125
55.5
2.5
0.50
5.00
−5.405
WSS
53.4
7.4
2.8
2.64
−4.187
FMC
53.5
2.3
0.49
4.65
−5.448
4
PGN
0.150
0.680
105.0
9.6
2.3
4.17
−4.159
WSS
116.6
24.2
11.4
2.12
−3.062
FMC
100.5
7.3
3.1
2.36
−4.154
5
PGN
0.131
0.521
112.5
4.7
2.0
2.35
−4.530
WSS
105.3
22.6
10.3
2.19
−3.136
FMC
100.3
5.6
2.6
2.19
−4.350
6
PGN
0.212
0.550
100.0
5.8
2.3
2.52
−4.378
WSS
105.7
19.4
10.9
1.78
−3.178
FMC
91.1
5.2
2.4
2.21
−4.417
7
PGN
0.258
0.450
92.0
5.0
2.0
2.50
−4.503
WSS
91.3
16.3
9.9
1.65
−3.295
FMC
80.4
4.1
1.8
2.32
−4.642
8
PGN
0.152
0.365
110.0
3.8
1.9
2.00
−4.644
WSS
97.0
17.8
7.6
2.34
−3.372
FMC
92.4
4.3
1.8
2.36
−4.614
9
PGN
0.280
0.385
75.5
4.0
1.5
2.67
−4.725
WSS
79.9
14.8
8.8
1.68
−3.388
FMC
73.3
3.6
1.4
2.57
−4.788
10
PGN
0.380
0.498
70.0
4.4
1.2
3.67
−4.780
WSS
110.0
12.8
9.6
1.33
−3.413
FMC
68.9
4.0
1.7
2.42
−4.677
11
PGN
0.160
0.200
104.0
2.1
0.95
2.21
−5.203
WSS
92.0
11.2
4.5
2.49
−3.800
FMC
85.7
3.0
1.0
2.93
−5.022
12
PGN
0.228
0.250
72.0
3.1
0.90
3.44
−5.057
WSS
76.7
12.6
5.9
2.14
−3.632
FMC
72.8
3.2
0.99
3.22
−5.007
13
PGN
0.305
0.323
58.0
2.3
0.90
2.56
−5.187
WSS
68.0
13.5
7.4
1.82
−3.503
FMC
65.5
3.3
1.1
2.95
−4.935
14
PGN
0.385
0.393
65.5
3.8
1.6
2.38
−4.719
WSS
65.8
12.2
8.6
1.42
−3.482
FMC
61.2
3.3
1.3
2.53
−4.871
15
PGN
0.472
0.399
51.0
3.2
1.4
2.29
−4.852
WSS
55.4
9.5
8.0
1.19
−3.622
FMC
53.1
3.1
1.4
2.67
−4.868
16
PGN
0.527
0.350
20.0
2.6
1.3
2.00
−4.974
WSS
38.4
8.8
6.1
1.44
−3.773
FMC
43.5
2.8
1.4
1.98
−4.908
17
PGN
0.475
0.300
28.5
2.9
1.1
2.64
−5.000
WSS
41.5
10.9
5.3
2.06
−3.741
FMC
43.4
2.8
1.2
2.28
−4.972
18
PGN
0.510
0.236
29.5
2.4
1.2
2.00
−5.043
WSS
34.3
10.9
3.2
3.41
−3.960
FMC
32.8
2.7
1.2
2.19
−4.982
19
PGN
0.596
0.283
13.0
2.6
1.3
2.00
−4.974
WSS
31.0
8.3
3.5
2.37
−4.040
FMC
27.8
2.4
1.5
1.64
−4.941
20
PGN
0.344
0.284
60.0
2.3
0.90
2.56
−5.187
WSS
56.7
12.6
6.2
2.03
−3.610
FMC
56.9
3.1
0.97
3.16
−5.026
21
PGN
0.390
0.237
47.0
2.5
1.0
2.50
−5.105
WSS
45.3
11.8
4.5
2.62
−3.778
FMC
46.1
2.9
0.94
3.11
−5.063
22
PGN
0,441
0.198
34.5
2.8
0.95
2.95
−5.078
WSS
36.4
11.4
2.9
3.93
−3.984
FMC
35.5
2.9
1.0
2.83
−5.038
23
PGN
0.278
0.223
57.5
2.4
0.55
4.36
−5.382
WSS
62.1
11.5
5.1
2.26
−3.735
FMC
61.2
3.0
0.79
3.75
−5.137
24
PGN
0.300
0.163
54.0
2.9
0.60
4.83
−5.262
WSS
49.6
9.7
3.4
2.85
−3.985
FMC
49.8
2.7
0.64
4.19
−5.267
25
PGN
0.365
0.153
40.0
3.6
0.95
3.79
−4.969
WSS
38.8
10.1
2.5
4.04
−4.101
FMC
38.1
2.8
0.77
3.64
−5.165
Data of observer PGN refer to 2° test colors with a common luminance of L0 = Y0 = 48 cd · m−2 (approx.) surrounded by a 42° white surround with a luminance of 24 cd · m−2 (approx.). For details see Ref. 2. Data of observer WSS are those predicted by the line element of Stiles3 for similar observing conditions. Data of observer FMC are those predicted by the Friele–MacAdam–Chickering formulas9 whose parameters were optimized to give a best fit with the PGN ellipses.
Table IV
Color-matching ellipses of observers WRB and DLM.a
Color center
No.
Obs.
x0
y0
l0
θ(deg)
a(·103)
b(·103)
a/b
log10A
1′
WRB
0.580
0.341
0.253
171
3.0
1.6
1.88
−4.822
DLM
159
3.0
1.5
2.00
−4.850
2′
WRB
0.422
0.330
0.260
40
2.8
1.3
2.15
−4.912
DLM
25
2.9
1.4
2.07
−4.894
3′
WRB
0.364
0.505
0.243
67
2.4
1.1
2.18
−5.081
DLM
58
2.8
1.8
1.56
−4.800
4
WRB
0.370
0.218
0.195
35
2.7
1.0
2.70
−5.072
DLM
24
2.8
1.0
2.80
−5.056
5′
WRB
0.492
0.446
0.212
32
1.7
1.3
1.31
−5.158
DLM
18
2.0
1.0
2.00
−5.202
6′
WRB
0.308
0.424
0.201
72
2.8
0.8
3.50
−5.153
DLM
56
2.3
0.9
2.56
−5.187
7′
WRB
0.446
0.450
0.260
49
1.6
1.1
1.46
−5.257
DLM
3
1.7
1.0
1.70
−5.272
8′
WRB
0.319
0.581
0.230
90
2.3
1.5
1.53
−4.965
DLM
—
—
—
—
—
9
WRB
0.682
0.302
0.264
156
1.3
0.6
2.17
−5.611
DLM
150
1.3
0.8
1.62
−5.486
11
WRB
0.650
0.292
0.265
1
1.6
0.8
2.00
−5.396
DLM
174
1.7
0.8
2.12
−5.369
12
WRB
0.314
0.183
0.097
39
2.8
0.8
3.50
−5.153
DLM
32
2.5
0.7
3.57
−5.260
13
WRB
0.221
0.148
0.055
46
1.3
0.6
2.17
−5.611
DLM
46
1.2
0.4
3.00
−5.822
14
WRB
0.668
0.317
0.185
164
1.9
1.1
1.73
−5.183
DLM
162
2.0
0.9
2.22
−5.248
15
WRB
0.484
0.267
0.113
29
3.0
1.1
2.73
−4.984
DLM
15
2.7
1.5
1.80
−4.896
16′
WRB
0.436
0.366
0.211
17
2.7
1.1
2.46
−5.030
DLM
22
1.3
0.7
1.86
−5.544
17′
WRB
0.525
0.390
0.199
0
2.1
1.5
1.40
−5.004
DLM
168
2.3
1.0
2.30
−5.143
18
WRB
0.552
0.290
0.240
17
2.7
1.1
2.46
−5.030
DLM
16
2.6
1.1
2.36
−5.046
19
WRB
0.249
0.204
0.100
61
2.5
1.0
2.50
−5.105
DLM
56
2.3
0.8
2.88
−5.238
20′
WRB
0.258
0.325
0.165
79
3.1
1.3
2.38
−4.898
DLM
56
2.1
1.1
1.91
−5.139
21′
WRB
0.268
0.322
0.168
66
3.0
0.9
3.33
−5.072
DLM
59
1.8
0.9
2.00
−5.293
22′
WRB
0.310
0.288
0.160
61
2.8
1.1
2.54
−5.014
DLM
51
2.0
0.8
2.50
−5.299
23′
WRB
0.255
0.255
0.131
69
2.5
0.9
2.78
−5.151
DLM
60
2.4
0.9
2.67
−5.168
24′
WRB
0.383
0.489
0.280
90
1.8
1.2
1.50
−5.168
DLM
78
2.0
1.5
1.33
−5.026
25′
WRB
0.323
0.558
0.265
93
3.2
1.4
2.29
−4.852
DLM
83
2.4
1.4
1.71
−4.976
26′
WRB
0.354
0.358
0.267
43
2.7
1.1
2.46
−5.030
DLM
43
2.1
0.8
2.62
−5.278
27
WRB
0.416
0.236
0.231
40
1.8
1.1
1.64
−5.206
DLM
35
3.2
1.4
2.29
−4.852
28′
WRB
0.612
0.317
0.265
176
1.8
0.9
2.00
−5.293
DLM
143
2.1
1.0
2.10
−5.181
29′
WRB
0.473
0.317
0.313
27
1.6
1.0
1.60
−5.299
DLM
18
2.3
1.1
2.09
−5.100
30
WRB
0.358
0.230
0.220
42
2.3
0.8
2.88
−5.238
DLM
35
3.0
1.0
3.00
−5.026
31′
WRB
0.321
0.491
0.245
92
2.7
1.3
2.08
−4.957
DLM
71
2.2
1.1
2.00
−5.119
32′
WRB
0.294
0.367
0.258
78
2.1
1.1
1.91
−5.139
DLM
61
2.2
0.8
2.75
−5.257
33′
WRB
0.294
0.367
0.006
69
5.5
1.6
3.44
−4.558
DLM
69
3.5
1.2
2.92
−4.880
34′
WRB
0.385
0.400
0.275
62
2.0
0.9
2.22
−5.248
DLM
38
1.6
1.3
1.23
−5.185
35
WRB
0.199
0.524
0.139
97
5.1
2.3
2.22
−4.434
DLM
90
5.0
1.3
3.85
−4.690
36
WRB
0.212
0.642
0. 135
98
8.3
1.8
4.61
−4.328
DLM
83
5.2
2.3
2.26
−4.425
37
WRB
0.203
0.419
0.146
107
3.9
1.1
3.54
−4.870
DLM
106
4.2
1.6
2.62
−4.676
38
WRB
0.171
0.189
0.188
92
2.3
0.6
3.83
−5.363
DLM
89
2.3
0.4
3.75
−5.539
39
WRB
0.191
0.329
0.152
86
3.6
1.0
3.60
−4.946
DLM
100
2.3
1.1
2.09
−5.100
The color-matching ellipses are cross sections through the centers of color-matching ellipsoids determined for 2° test colors of different luminances (l0 = 0.2 log10Y0, with Y0 ≡ L0 in cd · m−2) presented in a dark surround. For details see Ref. 2 or 3. The numbers of the test colors are those used by Brown and MacAdam2; there is no No. 10. Test colors 32 and 33 have the same chromaticity and differ only in luminance [Y0 (32) = 19.6 cd · m−2; Y0 (33) = 1.1 cd · m−2]. Test colors marked with a prime, e.g., 1′, 2′, etc., are within the chromaticity gamut of Fig. 2 of this paper.
The color-matching ellipses are cross sections through the centers of (weighted) mean color-matching ellipsoids determined by a group of 12 observers for 10° test colors of different luminances (l0 = 0.2 log10Y0, with Y0 ≡ L0 in cd · m−2) presented in a large near-white surround with a luminance of 8.9 cd.m−2 (that is, l0 = 0.190). For details see Ref. 15 or 3. Test color (13) is identical to test color 13 except that its angular subtense is reduced to 2°. Test colors marked with a prime, e.g., 1′, 2′, etc., are within the chromaticity gamut of Fig. 2 of this paper.
Table VI
Numerical correlations between sets of color-matching ellipses of different observers.a
Observer G
Scaling factor α and correlation coefficient
Observer g
GF
AR
FMC
α
〈x〉
α
〈x〉
α
〈x〉
α
〈x〉
1.0
1.00
0.360
1.00
0.443
1.00
0.448
α1
0.86
0.280
0.83
0.327
1.42
0.477
α2
0.80
0.270
0.75
0.311
1.15
0.430
GW
1.0
〈d〉
1.00
0.260
1.00
0.300
1.00
0.411
α1
〈d1〉
0.86
0.223
0.83
0.237
1.42
0.363
α3
〈d3〉
0.84
0.222
0.80
0.235
1.36
0.361
DLM
FMC
1.0
1.00
0.298
1.00
0.297
α1
0.91
0.253
1.17
0.303
WRB
α2
0.85
0.245
1.07
0.290
1.0
〈d〉
1.00
0.240
1.00
0.252
α1
〈d1〉
0.91
0.212
1.17
0.243
α3
〈d3〉
0.85
0.208
1.11
0.239
FMC
1.0
1.00
0.175
α1
1.01
0.176
PGN
α2
0.98
0.173
1.0
〈d〉
1.00
0.142
α1
〈d1〉
1.01
0.142
α3
〈d3〉
0.98
0.141
All calculations were done with m = 18 chromaticity differences [see, for example, Eq. (5)]. The constant c2 was 7.81 in the calculations involving GW, and c2 = 1.0 in the calculations involving WRB and PGN as observer G.
Tables (6)
Table I
Color-matching ellipsoids and their cross sections of observers GF, AR, and GW.
The third coordinate l0 of the color center is constant for all 28 test colors; l0 = 0.2 log10Y0 = 0.2156, corresponding to a luminance L0 ≡ Y0 = 12 cd · m−2.
Supplementary to Table I. The data given in row M correspond to a mean ellipsoid and its cross section for the respective test color; these data are identical to those given in Table 1.
Table III
Color-matching ellipses of observers PGN, WSS, and FMC.a
Color center
No.
Obs.
x0
y0
θ(deg)
a(·103)
b(·103)
a/b
log10A
1
PGN
0.160
0.057
62.5
0.85
0.35
2.43
−6.029
WSS
85.5
2.4
1.4
1.71
−4.977
FMC
76.4
1.1
0.34
3.20
−5.926
2
PGN
0.187
0.118
77.0
2.2
0.55
4.00
−5.420
WSS
76.8
6.3
2.9
2.17
−4.241
FMC
72.0
2.0
0.53
3.88
−5.469
3
PGN
0.253
0.125
55.5
2.5
0.50
5.00
−5.405
WSS
53.4
7.4
2.8
2.64
−4.187
FMC
53.5
2.3
0.49
4.65
−5.448
4
PGN
0.150
0.680
105.0
9.6
2.3
4.17
−4.159
WSS
116.6
24.2
11.4
2.12
−3.062
FMC
100.5
7.3
3.1
2.36
−4.154
5
PGN
0.131
0.521
112.5
4.7
2.0
2.35
−4.530
WSS
105.3
22.6
10.3
2.19
−3.136
FMC
100.3
5.6
2.6
2.19
−4.350
6
PGN
0.212
0.550
100.0
5.8
2.3
2.52
−4.378
WSS
105.7
19.4
10.9
1.78
−3.178
FMC
91.1
5.2
2.4
2.21
−4.417
7
PGN
0.258
0.450
92.0
5.0
2.0
2.50
−4.503
WSS
91.3
16.3
9.9
1.65
−3.295
FMC
80.4
4.1
1.8
2.32
−4.642
8
PGN
0.152
0.365
110.0
3.8
1.9
2.00
−4.644
WSS
97.0
17.8
7.6
2.34
−3.372
FMC
92.4
4.3
1.8
2.36
−4.614
9
PGN
0.280
0.385
75.5
4.0
1.5
2.67
−4.725
WSS
79.9
14.8
8.8
1.68
−3.388
FMC
73.3
3.6
1.4
2.57
−4.788
10
PGN
0.380
0.498
70.0
4.4
1.2
3.67
−4.780
WSS
110.0
12.8
9.6
1.33
−3.413
FMC
68.9
4.0
1.7
2.42
−4.677
11
PGN
0.160
0.200
104.0
2.1
0.95
2.21
−5.203
WSS
92.0
11.2
4.5
2.49
−3.800
FMC
85.7
3.0
1.0
2.93
−5.022
12
PGN
0.228
0.250
72.0
3.1
0.90
3.44
−5.057
WSS
76.7
12.6
5.9
2.14
−3.632
FMC
72.8
3.2
0.99
3.22
−5.007
13
PGN
0.305
0.323
58.0
2.3
0.90
2.56
−5.187
WSS
68.0
13.5
7.4
1.82
−3.503
FMC
65.5
3.3
1.1
2.95
−4.935
14
PGN
0.385
0.393
65.5
3.8
1.6
2.38
−4.719
WSS
65.8
12.2
8.6
1.42
−3.482
FMC
61.2
3.3
1.3
2.53
−4.871
15
PGN
0.472
0.399
51.0
3.2
1.4
2.29
−4.852
WSS
55.4
9.5
8.0
1.19
−3.622
FMC
53.1
3.1
1.4
2.67
−4.868
16
PGN
0.527
0.350
20.0
2.6
1.3
2.00
−4.974
WSS
38.4
8.8
6.1
1.44
−3.773
FMC
43.5
2.8
1.4
1.98
−4.908
17
PGN
0.475
0.300
28.5
2.9
1.1
2.64
−5.000
WSS
41.5
10.9
5.3
2.06
−3.741
FMC
43.4
2.8
1.2
2.28
−4.972
18
PGN
0.510
0.236
29.5
2.4
1.2
2.00
−5.043
WSS
34.3
10.9
3.2
3.41
−3.960
FMC
32.8
2.7
1.2
2.19
−4.982
19
PGN
0.596
0.283
13.0
2.6
1.3
2.00
−4.974
WSS
31.0
8.3
3.5
2.37
−4.040
FMC
27.8
2.4
1.5
1.64
−4.941
20
PGN
0.344
0.284
60.0
2.3
0.90
2.56
−5.187
WSS
56.7
12.6
6.2
2.03
−3.610
FMC
56.9
3.1
0.97
3.16
−5.026
21
PGN
0.390
0.237
47.0
2.5
1.0
2.50
−5.105
WSS
45.3
11.8
4.5
2.62
−3.778
FMC
46.1
2.9
0.94
3.11
−5.063
22
PGN
0,441
0.198
34.5
2.8
0.95
2.95
−5.078
WSS
36.4
11.4
2.9
3.93
−3.984
FMC
35.5
2.9
1.0
2.83
−5.038
23
PGN
0.278
0.223
57.5
2.4
0.55
4.36
−5.382
WSS
62.1
11.5
5.1
2.26
−3.735
FMC
61.2
3.0
0.79
3.75
−5.137
24
PGN
0.300
0.163
54.0
2.9
0.60
4.83
−5.262
WSS
49.6
9.7
3.4
2.85
−3.985
FMC
49.8
2.7
0.64
4.19
−5.267
25
PGN
0.365
0.153
40.0
3.6
0.95
3.79
−4.969
WSS
38.8
10.1
2.5
4.04
−4.101
FMC
38.1
2.8
0.77
3.64
−5.165
Data of observer PGN refer to 2° test colors with a common luminance of L0 = Y0 = 48 cd · m−2 (approx.) surrounded by a 42° white surround with a luminance of 24 cd · m−2 (approx.). For details see Ref. 2. Data of observer WSS are those predicted by the line element of Stiles3 for similar observing conditions. Data of observer FMC are those predicted by the Friele–MacAdam–Chickering formulas9 whose parameters were optimized to give a best fit with the PGN ellipses.
Table IV
Color-matching ellipses of observers WRB and DLM.a
Color center
No.
Obs.
x0
y0
l0
θ(deg)
a(·103)
b(·103)
a/b
log10A
1′
WRB
0.580
0.341
0.253
171
3.0
1.6
1.88
−4.822
DLM
159
3.0
1.5
2.00
−4.850
2′
WRB
0.422
0.330
0.260
40
2.8
1.3
2.15
−4.912
DLM
25
2.9
1.4
2.07
−4.894
3′
WRB
0.364
0.505
0.243
67
2.4
1.1
2.18
−5.081
DLM
58
2.8
1.8
1.56
−4.800
4
WRB
0.370
0.218
0.195
35
2.7
1.0
2.70
−5.072
DLM
24
2.8
1.0
2.80
−5.056
5′
WRB
0.492
0.446
0.212
32
1.7
1.3
1.31
−5.158
DLM
18
2.0
1.0
2.00
−5.202
6′
WRB
0.308
0.424
0.201
72
2.8
0.8
3.50
−5.153
DLM
56
2.3
0.9
2.56
−5.187
7′
WRB
0.446
0.450
0.260
49
1.6
1.1
1.46
−5.257
DLM
3
1.7
1.0
1.70
−5.272
8′
WRB
0.319
0.581
0.230
90
2.3
1.5
1.53
−4.965
DLM
—
—
—
—
—
9
WRB
0.682
0.302
0.264
156
1.3
0.6
2.17
−5.611
DLM
150
1.3
0.8
1.62
−5.486
11
WRB
0.650
0.292
0.265
1
1.6
0.8
2.00
−5.396
DLM
174
1.7
0.8
2.12
−5.369
12
WRB
0.314
0.183
0.097
39
2.8
0.8
3.50
−5.153
DLM
32
2.5
0.7
3.57
−5.260
13
WRB
0.221
0.148
0.055
46
1.3
0.6
2.17
−5.611
DLM
46
1.2
0.4
3.00
−5.822
14
WRB
0.668
0.317
0.185
164
1.9
1.1
1.73
−5.183
DLM
162
2.0
0.9
2.22
−5.248
15
WRB
0.484
0.267
0.113
29
3.0
1.1
2.73
−4.984
DLM
15
2.7
1.5
1.80
−4.896
16′
WRB
0.436
0.366
0.211
17
2.7
1.1
2.46
−5.030
DLM
22
1.3
0.7
1.86
−5.544
17′
WRB
0.525
0.390
0.199
0
2.1
1.5
1.40
−5.004
DLM
168
2.3
1.0
2.30
−5.143
18
WRB
0.552
0.290
0.240
17
2.7
1.1
2.46
−5.030
DLM
16
2.6
1.1
2.36
−5.046
19
WRB
0.249
0.204
0.100
61
2.5
1.0
2.50
−5.105
DLM
56
2.3
0.8
2.88
−5.238
20′
WRB
0.258
0.325
0.165
79
3.1
1.3
2.38
−4.898
DLM
56
2.1
1.1
1.91
−5.139
21′
WRB
0.268
0.322
0.168
66
3.0
0.9
3.33
−5.072
DLM
59
1.8
0.9
2.00
−5.293
22′
WRB
0.310
0.288
0.160
61
2.8
1.1
2.54
−5.014
DLM
51
2.0
0.8
2.50
−5.299
23′
WRB
0.255
0.255
0.131
69
2.5
0.9
2.78
−5.151
DLM
60
2.4
0.9
2.67
−5.168
24′
WRB
0.383
0.489
0.280
90
1.8
1.2
1.50
−5.168
DLM
78
2.0
1.5
1.33
−5.026
25′
WRB
0.323
0.558
0.265
93
3.2
1.4
2.29
−4.852
DLM
83
2.4
1.4
1.71
−4.976
26′
WRB
0.354
0.358
0.267
43
2.7
1.1
2.46
−5.030
DLM
43
2.1
0.8
2.62
−5.278
27
WRB
0.416
0.236
0.231
40
1.8
1.1
1.64
−5.206
DLM
35
3.2
1.4
2.29
−4.852
28′
WRB
0.612
0.317
0.265
176
1.8
0.9
2.00
−5.293
DLM
143
2.1
1.0
2.10
−5.181
29′
WRB
0.473
0.317
0.313
27
1.6
1.0
1.60
−5.299
DLM
18
2.3
1.1
2.09
−5.100
30
WRB
0.358
0.230
0.220
42
2.3
0.8
2.88
−5.238
DLM
35
3.0
1.0
3.00
−5.026
31′
WRB
0.321
0.491
0.245
92
2.7
1.3
2.08
−4.957
DLM
71
2.2
1.1
2.00
−5.119
32′
WRB
0.294
0.367
0.258
78
2.1
1.1
1.91
−5.139
DLM
61
2.2
0.8
2.75
−5.257
33′
WRB
0.294
0.367
0.006
69
5.5
1.6
3.44
−4.558
DLM
69
3.5
1.2
2.92
−4.880
34′
WRB
0.385
0.400
0.275
62
2.0
0.9
2.22
−5.248
DLM
38
1.6
1.3
1.23
−5.185
35
WRB
0.199
0.524
0.139
97
5.1
2.3
2.22
−4.434
DLM
90
5.0
1.3
3.85
−4.690
36
WRB
0.212
0.642
0. 135
98
8.3
1.8
4.61
−4.328
DLM
83
5.2
2.3
2.26
−4.425
37
WRB
0.203
0.419
0.146
107
3.9
1.1
3.54
−4.870
DLM
106
4.2
1.6
2.62
−4.676
38
WRB
0.171
0.189
0.188
92
2.3
0.6
3.83
−5.363
DLM
89
2.3
0.4
3.75
−5.539
39
WRB
0.191
0.329
0.152
86
3.6
1.0
3.60
−4.946
DLM
100
2.3
1.1
2.09
−5.100
The color-matching ellipses are cross sections through the centers of color-matching ellipsoids determined for 2° test colors of different luminances (l0 = 0.2 log10Y0, with Y0 ≡ L0 in cd · m−2) presented in a dark surround. For details see Ref. 2 or 3. The numbers of the test colors are those used by Brown and MacAdam2; there is no No. 10. Test colors 32 and 33 have the same chromaticity and differ only in luminance [Y0 (32) = 19.6 cd · m−2; Y0 (33) = 1.1 cd · m−2]. Test colors marked with a prime, e.g., 1′, 2′, etc., are within the chromaticity gamut of Fig. 2 of this paper.
The color-matching ellipses are cross sections through the centers of (weighted) mean color-matching ellipsoids determined by a group of 12 observers for 10° test colors of different luminances (l0 = 0.2 log10Y0, with Y0 ≡ L0 in cd · m−2) presented in a large near-white surround with a luminance of 8.9 cd.m−2 (that is, l0 = 0.190). For details see Ref. 15 or 3. Test color (13) is identical to test color 13 except that its angular subtense is reduced to 2°. Test colors marked with a prime, e.g., 1′, 2′, etc., are within the chromaticity gamut of Fig. 2 of this paper.
Table VI
Numerical correlations between sets of color-matching ellipses of different observers.a
Observer G
Scaling factor α and correlation coefficient
Observer g
GF
AR
FMC
α
〈x〉
α
〈x〉
α
〈x〉
α
〈x〉
1.0
1.00
0.360
1.00
0.443
1.00
0.448
α1
0.86
0.280
0.83
0.327
1.42
0.477
α2
0.80
0.270
0.75
0.311
1.15
0.430
GW
1.0
〈d〉
1.00
0.260
1.00
0.300
1.00
0.411
α1
〈d1〉
0.86
0.223
0.83
0.237
1.42
0.363
α3
〈d3〉
0.84
0.222
0.80
0.235
1.36
0.361
DLM
FMC
1.0
1.00
0.298
1.00
0.297
α1
0.91
0.253
1.17
0.303
WRB
α2
0.85
0.245
1.07
0.290
1.0
〈d〉
1.00
0.240
1.00
0.252
α1
〈d1〉
0.91
0.212
1.17
0.243
α3
〈d3〉
0.85
0.208
1.11
0.239
FMC
1.0
1.00
0.175
α1
1.01
0.176
PGN
α2
0.98
0.173
1.0
〈d〉
1.00
0.142
α1
〈d1〉
1.01
0.142
α3
〈d3〉
0.98
0.141
All calculations were done with m = 18 chromaticity differences [see, for example, Eq. (5)]. The constant c2 was 7.81 in the calculations involving GW, and c2 = 1.0 in the calculations involving WRB and PGN as observer G.