Shenzhen ThreeNH Technology Co., Ltd.
Shenzhen ThreeNH Technology Co., Ltd Since 1998, 3nh has been a professional factory with 20 years experience on color and glossy measurement industry.
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Fluorescent Light Tube D65 D50 TL83 U30 Different Color Temperature
CIE Standard Illuminant D65 (sometimes written D65[1][2]) is a commonly used standard illuminant defined by the International Commission on Illumination (CIE).[3] 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.[4][5]
The CIE positions D65 as the standard daylight illuminant:
[D65] is intended to represent average daylight and has a correlated colour temperature of approximately 6500 K. CIE standard illuminant D65 should be used in all colorimetric calculations requiring representative daylight, unless there are specific reasons for using a different illuminant. Variations in the relative spectral power distribution of daylight are known to occur, particularly in the ultraviolet spectral region, as a function of season, time of day, and geographic location.
— ISO 10526:1999/CIE S005/E-1998, CIE Standard Illuminants for Colorimetry