Determination of the Tristimulus Values of the Spectrum for Eight Egyptian Observers and One British Observer

I. G. H. Ishak

doi:10.1364/JOSA.42.000844

Journal of the Optical Society of America
Vol. 42,
Issue 11,
pp. 844-849
(1952)
•https://doi.org/10.1364/JOSA.42.000844

Determination of the Tristimulus Values of the Spectrum for Eight Egyptian Observers and One British Observer

I. G. H. Ishak

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I. G. H. Ishak, "Determination of the Tristimulus Values of the Spectrum for Eight Egyptian Observers and One British Observer," J. Opt. Soc. Am. 42, 844-849 (1952)

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Abstract

The relative luminances of the matching stimuli were recorded for eight Egyptian observers and one British observer with normal color vision on Wright’s colorimeter. Results for the Egyptians were compared with similar measurements made on 11 British observers and no significant differences between the means of the two sets were found. These two sets of values were found to be different from the adopted values for the C.I.E. after the transformation of the latter to the unit basis used by Wright.

From the relative luminances of the matching stimuli, the spectral luminosity curve and the chromaticity coordinates of the eight Egyptians and the one British observer, their tristimulus values were computed in the usual manner. A marked difference in the blue values was found between the Egyptian observers and the available data for four British observers. The blue values were very low in the case of the Egyptians and the denser yellow pigmentation of the Egyptians could not account for all the differences.

The spectral tristimulus values were calculated for Wright, Guild, Weaver, Abney, and the C.I.E. from the combination of their data on the spectral chromaticity coordinates, together with the C.I.E. relative luminances of the matching stimuli and spectral luminosity curve.

When their results were used in calculating the chromaticity of the standard sources S_A, S_B, and S_C, it was found that Wright, Weaver, and Abney gave results which are very close to each other but deviate considerably from Guild’s results, while the C.I.E. values lie in between.

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Observer	Relative luminance of one unit of the matching stimuli (units based on matches 0.5825μ and 0.494μ)
Observer	red (0.65μ)	green (0.53μ)	blue (0.46μ)
M.K.	0.622	1.00	0.053
M. T.	0.671	1.00	0.052
S. A. S.	0.608	1.00	0.085
A. M. A.	0.702	1.00	0.047
I. G. H. I.	0.760	1.00	0.063
A. K. A.	0.609	1.00	0.041
E. G. T.	0.530	1.00	0.046
S. K. T.	0.658	1.00	0.049
Average	0.645	1.00	0.0545

Observer	Relative luminance of one unit of the matching stimuli (units based on matches 0.5825μ and 0.494μ)
Observer	red (0.65μ)	green (0.53μ)	blue (0.46μ)
A	0.572	1.00	0.065
B	0.708	1.00	0.048
C	0.588	1.00	0.060
D	0.568	1.00	0.046
E	0.841	1.00	0.046
F	0.736	1.00	0.047
G	0.648	1.00	0.051
L. C. T.	0.570	1.00	0.058
W. D. W.	0.648	1.00	0.051
F. H. G.	0.725	1.00	0.056
J. H. N.	0.711	1.00	0.068
Average	0.665	1.00	0.0542

λ in μ	I.G.H.I.			A.K.A.			E.G.T.			S.K.T.
λ in μ	$\bar{r} L_{r} (0.65 μ)$	$\bar{g} L_{g} (0.53 μ)$	$\bar{b} L_{b} (0.46 μ)$	$\bar{r} L_{r} (0.65 μ)$	$\bar{g} L_{g} (0.53 μ)$	$\bar{b} L_{b} (0.46 μ)$	$\bar{r} L_{r} (0.65 μ)$	$\bar{g} L_{g} (0.53 μ)$	$\bar{b} L_{b} (0.46 μ)$	$\bar{r} L_{r} (0.65 μ)$	$\bar{g} L_{g} (0.53 μ)$	$\bar{b} L_{b} (0.46 μ)$
0.41	0.001	−0.002	0.003	0.006	−0.007	0.014	0.003	−0.007	0.006	0.005	−0.010	0.012
0.42	0.002	−0.004	0.006	0.007	−0.006	0.016	0.002	−0.004	0.006	0.004	−0.006	0.011
0.43	0.003	−0.005	0.012	0.007	−0.003	0.029	0.003	−0.003	0.009	0.004	−0.004	0.011
0.44	0.002	−0.006	0.021	0.009	−0.018	0.061	0.003	−0.007	0.019	0.005	−0.009	0.025
0.45	0.002	−0.006	0.025	0.008	−0.020	0.073	0.004	−0.002	0.035	0.004	−0.010	0.028
0.46	⋯	⋯	0.032	⋯	⋯	0.090	⋯	⋯	0.028	⋯	⋯	0.024
0.47	−0.008	0.043	0.023	−0.015	0.098	0.062	−0.010	0.035	0.023	−0.010	0.032	0.021
0.48	−0.019	0.090	0.020	−0.023	0.156	0.031	−0.012	0.073	0.012	−0.017	0.058	0.015
0.49	−0.022	0.121	0.011	−0.034	0.264	0.020	−0.010	0.096	0.006	−0.019	0.106	0.007
0.50	−0.029	0.209	0.007	−0.031	0.354	0.008	−0.017	0.179	0.004	−0.028	0.122	0.006
0.51	−0.034	0.405	0.005	−0.034	0.482	0.003	−0.022	0.351	0.003	−0.030	0.357	0.003
0.52	−0.020	0.578	0.001	−0.028	0.656	0.001	−0.017	0.564	0.001	−0.026	0.603	0.002
0.53	⋯	0.753	⋯	⋯	0.718	⋯	⋯	0.752	⋯	⋯	0.824	⋯
0.54	0.049	0.800	−0.002	0.031	0.823	−0.001	0.036	0.820	−0.001	0.048	0.920	−0.001
0.55	0.119	0.815	−0.004	0.095	0.831	−0.002	0.077	0.839	−0.002	0.100	0.895	−0.002
0.56	0.200	0.805	−0.005	0.182	0.820	−0.003	0.138	0.864	−0.003	0.173	0.829	−0.002
0.57	0.260	0.656	−0.005	0.220	0.644	−0.003	0.194	0.738	−0.003	0.227	0.679	−0.002
0.58	0.329	0.516	−0.004	0.244	0.439	−0.002	0.251	0.571	−0.002	0.277	0.508	−0.002
0.59	0.339	0.334	−0.003	0.249	0.275	−0.001	0.293	0.394	−0.001	0.270	0.309	−0.001
0.60	0.371	0.209	−0.003	0.244	0.170	−0.001	0.340	0.281	−0.001	0.303	0.178	−0.001
0.61	0.358	0.113	−0.002	0.221	0.084	−0.001	0.349	0.162	−0.001	0.255	0.082	−0.001
0.62	0.318	0.056	−0.001	0.175	0.038	⋯	0.298	0.068	⋯	0.193	0.030	⋯
0.63	0.247	0.022	−0.001	0.128	0.014	⋯	0.221	0.028	⋯	0.120	0.011	⋯
0.64	0.176	0.006	⋯	0.082	0.003	⋯	0.155	0.008	⋯	0.073	0.003	⋯
0.65	0.124	⋯	⋯	0.054	⋯	⋯	0.109	⋯	⋯	0.044	⋯	⋯
0.66	0.104	−0.002	⋯	0.030	⋯	⋯	0.065	−0.001	⋯	0.026	⋯	⋯
0.67	0.057	−0.001	⋯	0.015	⋯	⋯	0.036	−0.001	⋯	0.015	⋯	⋯
0.68	0.024	−0.001	⋯	0.005	⋯	⋯	0.017	−0.001	⋯	0.008	⋯	⋯
0.69	0.013	⋯	⋯	0.003	⋯	⋯	0.009	⋯	⋯	0.004	⋯	⋯
0.70	0.006	⋯	⋯	0.002	⋯	⋯	0.004	⋯	⋯	0.002	⋯	⋯
	A.M.A.			S.A.S.			M.T.			M.K.
λ in μ	$\bar{r} L_{r} (0.65 μ)$	$\bar{g} L_{g} (0.53 μ)$	$\bar{b} L_{b} (0.46 μ)$	$\bar{r} L_{r} (0.65 μ)$	$\bar{g} L_{g} (0.53 μ)$	$\bar{b} L_{b} (0.46 μ)$	$\bar{r} L_{r} (0.65 μ)$	$\bar{g} L_{g} (0.53 μ)$	$\bar{b} L_{b} (0.46 μ)$	$\bar{r} L_{r} (0.65 μ)$	$\bar{g} L_{g} (0.53 μ)$	$\bar{b} L_{b} (0.46 μ)$
0.41	0.003	−0.006	0.004	0.006	−0.001	0.014	0.003	−0.007	0.007	0.004	−0.005	0.007
0.42	0.004	−0.004	0.007	0.004	−0.004	0.014	0.006	−0.015	0.019	0.005	−0.006	0.014
0.43	0.005	−0.005	0.013	0.002	−0.001	0.018	0.012	−0.030	0.035	0.004	−0.008	0.027
0.44	0.007	−0.016	0.030	0.003	−0.007	0.042	0.010	−0.038	0.058	0.004	−0.023	0.056
0.45	0.008	−0.027	0.044	0.002	−0.008	0.055	0.004	−0.021	0.053	0.001	−0.020	0.060
0.46	⋯	⋯	0.043	⋯	⋯	0.068	⋯	⋯	0.039	⋯	⋯	0.060
0.47	−0.014	0.061	0.026	−0.012	0.076	0.044	−0.007	0.051	0.024	−0.006	0.056	0.047
0.48	−0.012	0.092	0.017	−0.020	0.134	0.025	−0.010	0.125	0.018	−0.026	0.132	0.026
0.49	−0.026	0.156	0.010	−0.024	0.200	0.015	−0.016	0.156	0.010	−0.031	0.185	0.014
0.50	−0.032	0.267	0.007	−0.030	0.322	0.008	−0.026	0.198	0.006	−0.040	0.322	0.009
0.51	−0.037	0.407	0.003	−0.039	0.515	0.005	−0.044	0.423	0.005	−0.039	0.492	0.004
0.52	−0.030	0.592	0.001	−0.025	0.692	0.002	−0.026	0.524	0.002	−0.019	0.667	0.001
0.53	⋯	0.718	⋯	⋯	0.859	⋯	⋯	0.676	⋯	⋯	0.785	⋯
0.54	0.035	0.798	−0.001	0.039	0.875	−0.001	0.038	0.793	−0.001	0.046	0.865	−0.002
0.55	0.106	0.896	−0.002	0.084	0.918	−0.002	0.102	0.830	−0.002	0.114	0.833	−0.004
0.56	0.178	0.816	−0.003	0.142	0.834	−0.003	0.178	0.824	−0.003	0.174	0.823	−0.005
0.57	0.253	0.690	−0.003	0.206	0.700	−0.003	0.236	0.638	−0.003	0.244	0.712	−0.005
0.58	0.302	0.508	−0.002	0.276	0.526	−0.002	0.311	0.508	−0.002	0.304	0.518	−0.003
0.59	0.340	0.336	−0.002	0.299	0.325	−0.002	0.402	0.346	−0.002	0.344	0.334	−0.002
0.60	0.351	0.219	−0.001	0.345	0.219	−0.001	0.434	0.210	−0.001	0.358	0.225	−0.001
0.61	0.324	0.114	−0.001	0.346	0.132	−0.001	0.400	0.119	−0.001	0.329	0.112	⋯
0.62	0.275	0.049	−0.001	0.301	0.056	−0.001	0.341	0.065	−0.001	0.265	0.053	⋯
0.63	0.216	0.021	⋯	0.214	0.022	⋯	0.263	0.030	⋯	0.205	0.028	⋯
0.64	0.157	0.006	⋯	0.150	0.007	⋯	0.190	0.008	⋯	0.152	0.009	⋯
0.65	0.100	⋯	⋯	0.108	⋯	⋯	0.134	⋯	⋯	0.101	⋯	⋯
0.66	0.053	⋯	⋯	0.067	−0.001	⋯	0.086	−0.002	⋯	0.057	−0.001	⋯
0.67	0.031	−0.001	⋯	0.035	−0.001	⋯	0.046	−0.002	⋯	0.029	−0.001	⋯
0.68	0.014	⋯	⋯	0.018	−0.001	⋯	0.018	−0.001	⋯	0.011	−0.001	⋯
0.69	0.008	⋯	⋯	0.008	⋯	⋯	0.009	⋯	⋯	0.006	⋯	⋯
0.70	0.003	⋯	⋯	0.004	⋯	⋯	0.003	⋯	⋯	0.003	⋯	⋯

λ in μ	L.C.T.
λ in μ	$\bar{r} L_{r} (0.65 μ)$	$\bar{g} L_{g} (0.53 μ)$	$\bar{b} L_{b} (0.46 μ)$
0.41	0.008	−0.032	0.029
0.42	0.013	−0.064	0.062
0.43	0.011	−0.044	0.053
0.44	0.008	−0.022	0.040
0.45	⋯	−0.002	0.033
0.46	⋯	⋯	0.040
0.47	−0.012	0.048	0.024
0.48	−0.019	0.082	0.016
0.49	−0.018	⋯	⋯
0.50	−0.024	0.213	0.007
0.51	−0.025	0.357	0.004
0.52	−0.024	0.593	0.002
0.53	⋯	0.734	⋯
0.54	0.036	0.784	−0.002
0.55	0.083	0.857	−0.002
0.56	0.152	0.851	−0.003
0.57	0.208	0.687	−0.002
0.58	0.259	0.519	−0.002
0.59	0.291	0.374	−0.001
0.60	0.316	0.240	−0.001
0.61	0.320	0.140	⋯
0.62	0.279	0.078	⋯
0.63	0.207	0.031	⋯
0.64	0.152	0.010	⋯
0.65	0.108	⋯	⋯
0.66	0.057	−0.001	⋯
0.67	0.030	−0.001	⋯
0.68	0.015	⋯	⋯
0.69	0.007	⋯	⋯
0.70	0.003	⋯	⋯

	Red 0.65μ	Green 0.53μ	Blue 0.46μ
C.I.E.	0.614	1.00	0.047
Mean of 8 Egyptians	0.645	1.00	0.0545
Mean of 11 British	0.665	1.00	0.0542
Wright’s (calculated)	0.650	1.00	0.044

Abstract

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Tables (6)

Equations (48)

Journal of the Optical Society of America