correlated colour temperature [Tcp]
temperature of the Planckian radiator having the chromaticity nearest the chromaticity associated with the given spectral distribution on a diagram where the (CIE 1931 standard observer based) coordinates of the Planckian locus and the test stimulus are depictedUnit: KNOTE 1 The concept of correlated colour temperature should not be used if the chromaticity of the test source differs more than from the Planckian radiator, where refer to the test source, to the Planckian radiator.NOTE 2 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 e.g. 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). Abbreviation: “CCT”