Estimation equations for practical use on lightness‐reflectance (L/Y) ratios in the whole chromaticity gamut

Publisher Website
Google Scholar
Abstract
A multiple regression analysis is reported to predict L/Y ratios as a function of chromaticity coordinates x, y. the specified variables were selected statistically from the 20 terms of Ψmψn. the quantities Ψ, ψ are the transformed values of x, y, respectively, and 1 ≦ m + n ≦ 5. the contour lines of equal L/Y ratios are estimated in the whole chromaticity gamut including spectral colors by using each of the regression equations with 6, 9, and 20 specified variables. the regression equations with 20 specified variables can satisfactorily predict the corresponding experimental results. In case of regression equations with 6 specified variables, the predicted contour lines are significantly different in shape from those of the corresponding experiments. the same defects are found in the Ware‐Cowan equation only using 4 specified variables recommended by CIE Division 1 for further tests.