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—fluorescent (F), incandescent (I), and daylight (D). We study the behavior of the camera using the RGB and ClELAB coordinates for a wide set of color samples covering the visible spectrum. CIELAB coordinates are obtained from the tristimulus XYZ. Using linear methods, we obtain the XYZ values from the (RGB)CCD values acquired by a 3CCD camera. We propose two different approaches: the first is specific for each particular light source (F, I, and D); the second considers the equienergetic spectral light source as an approximation 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 evaluate the performance of the response of a 3CCD camera. The transformations that are specific for a given light source allow an improved response under change of illuminant in terms of color constancy.