Color measurement in standard CIELAB coordinates using a 3CCD camera: correction for the influence of the light source

We have analyzed the accuracy of the compensating performance of the white- balance mechanism of a 3CCD camera for the three common types of light-fluo rescent (F), incandescent (I), and daylight (D). We study the behavior of t he camera using the RGB and CIELAB coordinates for a wide set of color samp les covering the visible spectrum. CIELAB coordinates are obtained from the tristimulus XYZ. Using linear methods, we obtain the XYZ values from the ( RGB)cco values acquired by a 3CCD camera. We propose two different approach es: the first is specific for each particular light source (F, I, and D); t he second considers the equienergetic spectral light source as an approxima tion for white lighting. We measure the mean color difference in the CIELAB space under a change of illuminant and compare the results in order to eva luate the performance of the response of a BCCD camera. The transformations that are specific for a given light source allow an improved response unde r change of illuminant in terms of color constancy. (C) 2000 Society of Pho to-Optical Instrumentation Engineers.