Optics: measuring and testing – By shade or color – Trichromatic examination
Patent
1980-08-25
1982-06-15
Evans, F. L.
Optics: measuring and testing
By shade or color
Trichromatic examination
356419, G01J 350
Patent
active
043347827
ABSTRACT:
Method and apparatus for expressing as a number the relative brightness of artificial illumination as it is perceived by the average observer. There is extracted (i.e., detected) from the illumination to be measured, a blue-appearing narrow band, a green-appearing narrow band, a yellow-appearing narrow band and a red-orange-appearing narrow band. From these extracted bands are generated six different signals: a signal expressed as (aB) where (a) is about 0.23 and (B) is the watts of energy in the blue band, a signal expressed as (bG) where (b) is about 0.97 and (G) is the watts of energy in the green band, a signal expressed as (cR) where (c) is about 0.33 and (R) is the watts of energy in the red-orange band, a signal expressed as (dY) where (d) is about 0.19 and (Y) is the watts of energy in the yellow band, a signal expressed as (eG) where (e) is about 0.25 and (G) is the watts of energy in the green band, and a signal expressed as (fR) where (f) is about 0.25 and (R) is the watts of energy in the red-orange band. These signals are combined in the following manner: aB+bG+cR-dY+(the larger of eG and fR minus the smaller of eG and fR). These combined signals are expressed as a number which is indicative of the relative brightness of artificial illumination as perceived by the average observer.
REFERENCES:
patent: 2933010 (1960-04-01), Vlahos
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patent: 3818198 (1974-06-01), Walker et al.
patent: 4176294 (1979-11-01), Thornton, Jr.
Judd, Illuminating Engineering, Feb. 1958, pp. 61-71.
Walker, Applied Optics, vol. 11, No. 9, Sep. 1972, pp. 2060-2068.
Walker et al., Journal of the SMPTE, vol. 83, No. 9, Sep. 1974, pp. 737-741.
Chen Edward
Morton Edward W.
Rachko Dorothy
Thornton, Jr. William A.
Evans F. L.
Palmer W. D.
Westinghouse Electric Corp.
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