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IEVref:845-23-068ID:
Language:enStatus: Standard
Term: correlated colour temperature
Synonym1: CCT
Synonym2:
Synonym3:
Symbol: Tcp
Definition: temperature of a Planckian radiator having the chromaticity nearest the chromaticity associated with the given spectral distribution on a modified 1976 UCS diagram where u,23v are the coordinates of the Planckian locus and the test stimulus

Note 1 to entry: The concept of correlated colour temperature should not be used if the chromaticity of the test source differs more than ΔC=[(utup)2+49(vtvp)2]12=5×102 from the Planckian radiator, where ut,vt refer to the test source, and up,vp to the Planckian radiator.

Note 2 to entry: Correlated colour temperature can be calculated by a simple minimum search computer program that searches for that Planckian temperature that provides the smallest chromaticity difference between the test chromaticity and the Planckian locus, or for example by a method recommended by Robertson, A.R. "Computation of correlated color temperature and distribution temperature", J. Opt. Soc. Am. 58, 1528-1535, 1968. (Note that the values in some of the tables in this reference are not up to date.)

Note 3 to entry: The chromaticity diagram originally used to determine the correlated colour temperature was the CIE 1960 uniform-chromaticity-scale diagram. The CIE 1976 uniform-chromaticity-scale diagram is a modified version of the CIE 1960 uniform-chromaticity-scale diagram and is equivalent to the (u, 3/2 v) diagram.

Note 4 to entry: The correlated colour temperature is expressed in kelvin (K).

Note 5 to entry: This entry was numbered 845-03-50 in IEC 60050-845:1987.

Note 6 to entry: This note applies to the French language only.


Publication date:2020-12
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