High-accuracy method for calculating correlated color temperature with a lookup table based on golden section search

A high-accuracy method for calculating the correlated color temperature (CCT) of a light source was proposed through constructing a small-scale lookup table (LUT) based on the golden section search algorithm. The LUT, which only needs to be constructed once, is employed to narrow the search range of CCT. And it is easily extended to apply to a desired CCT range. The golden section search algorithm suitable for finding the extremum of a unimodal function is adopted to determine the CCT value of a test light source in a reduced range. The proposed method does not need to store a large number of precomputed data without utilizing any fitting operation. The method was tested in a wide range of chromaticity with CCT from 1000 K to 20,000 K and Duv from −0.03 to 0.03. The results show that relative to the combined solution, the proposed method can achieve significantly high accuracy, yielding an average error of 0.008 K and the maximum error less than 0.32 K. Furthermore, the calculation accuracy of the method is independent on the Duv value of a test light source.