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CIE Standard Illuminant D65 (sometimes written D65) is a commonly used standard illuminant defined by the International Commission on Illumination (CIE). It is part of the D series of illuminants that try to portray standard illumination conditions at open-air in different parts of the world. D65 corresponds roughly to the average midday light in Western Europe / Northern Europe (comprising both direct sunlight and the light diffused by a clear sky), hence it is also called a daylight illuminant. As any standard illuminant is represented as a table of averaged spectrophotometric data, any light source which statistically has the same relative spectral power distribution (SPD) can be considered a D65 light source. There are no actual D65 light sources, only simulators. The quality of a simulator can be assessed with the CIE Metamerism Index. The CIE positions D65 as the standard daylight illuminant: ==History== The CIE introduced three standard illuminants in 1931: * A: Incandescent bulb simulator * B: Daylight simulator (direct) * C: Daylight simulator (shade) B and C were derived from A by using liquid filters. The approximation to real light this provided was found lacking, so in 1967 the CIE accepted a proposal by Judd, MacAdam, and Wyszecki for a new series of daylight simulators, bearing the initial D. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Illuminant D65」の詳細全文を読む スポンサード リンク
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