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Allowable CCT Variations – ANSI C78.377

In some cases, clients would say that why my CCT test data is lower or higher than the nominal CCT.

An allowable range of tolerance or variation corresponds to each nominal CCT, both perpendicular to the curve and along the curve. Variations along the curve cause the light source to look more bluish or reddish, while those variations that are above and below the black-body curve cause the light to look more pinkish or greenish. These variations along the black body curve are measured in degrees Kelvin, while variations perpendicular to the curve are notated as Duv.

Within each color temperature’s color space, the allowable CCT variations both perpendicular and along to the curve define a quadrangle. The Duv and CCT ranges for the temperature of each color determine each quadrangle’s size.

Here show you the comparison of the same nominal CCT in 2-Step, 3-Step, 5-Step and 7-Step MacAdam Ellipses.


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