The purpose of the present study is to describe the subject of the presnt CIE method of specifying color rendering properties of light sources and to propose a revised method to solve the subject. The revised method is as follows: (1) Test color samples consist of eight colors selected from the MacBeth Color-Checker with two actual skin colors added.(2) 5reference illuminants are selected.(3) CIE LAB color space and CIE chromatic adaptation transform are used to calculate the color rendering indices of light sources.
The revised Ra values by this proposal correlated well with the Ra values of the present CIE method. A part of revised method of this proposal was suggested to CIE TC1-33.