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The distimulus method of assessing luminous efficiency of the spectrally pure stimuli
Author(s) -
Fry Glenn A.
Publication year - 1984
Publication title -
color research and application
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.393
H-Index - 62
eISSN - 1520-6378
pISSN - 0361-2317
DOI - 10.1002/col.5080090306
Subject(s) - photometry (optics) , stimulus (psychology) , brightness , luminance , monochromatic color , flicker , second order stimulus , hue , optics , mathematics , physics , astrophysics , stimulus control , computer science , psychology , stars , cognitive psychology , neuroscience , nicotine , operating system
In the tristimulus method of photometry, the luminance of any monochromatic stimulus can be assessed by matching it in hue and brightness to a mixture of two primaries and then reducing the saturation of the test stimulus to obtain a complete match. The luminances of the stimuli are considered to be additive, and the luminances of the two mixtures to be equal. In this article it is shown that if the primaries are properly chosen, it is not necessary to desaturate the test stimulus. The difference in saturation between the test stimulus and the mixture of the two primaries can be ignored and it may be assumed that the luminance of the test stimulus is equal to the sum of the luminances of the two primaries when the mixture and the test stimulus match in hue and brightness. Luminous efficiencies assessed in this way agree well with assessments based on flicker photometry. Flicker photometry has been used to assess the luminances of the primaries.