D65 Tube Light Philips T8 36W/965 TL-D 90 De Luxe
Model: TL-D 90 De Luxe
Watt: 36W
Size: 4 Feet
Type: T8
Brand: Philips
Origin: Poland
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 Tube Light Philips
D65 corresponds roughly to the average midday light in Western Europe
/ Northern Europe (comprising both direct sunlight
and the light diffused by a
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)
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
[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 ColorimetryD65 is a tabulated SPD in increments of 5 nm from 300 nm to 830 nm, using linear interpolation on the original data binned at 10 nm. The CIE recommends using linear interpolation of the component SPDs, S0, S1, and S2 if the application requires greater precision, but there is a proposal to use spline interpolation instead.
Using the standard 2° observer, the CIE 1931 color space chromaticity coordinates of D65 are
{displaystyle {begin{aligned}x&=0.31271=31.271%\y&=0.32902=32.902%\z&=0.35827=35.827%end{aligned}}}
Normalizing for relative luminance (i.e. set Y = 100), the XYZ tristimulus values are
{displaystyle {begin{aligned}X&=95.047\Y&=100\Z&=108.883end{aligned}}}
For the supplementary 10° observer,
{displaystyle {begin{aligned}x&=0.31382=31.382%\y&=0.33100=33.1%\z&=0.35518=35.518%end{aligned}}}and the corresponding XYZ tristimulus values are
{displaystyle {begin{aligned}X&=94.8110\Y&=100\Z&=107.304end{aligned}}}
Color Temperature
The name D65 suggests that the correlated color temperature (CCT)
revision of the constants in Planck’s law after the definition of the illuminant. This shifted the Planckian locus, affecting all CCTs, which are calculated by finding the nearest point on the locus to the white point.
The same discrepancy applies to all illuminants in the D series—D50, D55, D65, D75—and can be “rectified” by multiplying the nominal color temperature by {displaystyle {frac {c_{2}}{1.4380}}}; for example {displaystyle 6500 {text{K}}times {frac {1.438776877dots }{1.4380}}=6503.51 {text{K}}} for D65.
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