Vol. 34, Issue 6, pp. 1189-1197

We present an e$cient indexing/matching algorithm that is independent of the changes in the illuminant color and the
geometric conditions for 3-D object with multiple colors. The color contents of an object can be represented bythe peak
coordinates in the chromaticityhistogram space corresponding to the distinct colors in an image. The visible color areas
and their relative sizes of the histograms maychange with viewing conditions, but the coordinates of local maxima
remain stable. However, a change in illumination color results in a deformation of the chromaticitydistribution so as to
degrade the performance of color recognition. In order to discount lighting change, we de"ne a chromatic invariant that
normalizes the chromaticities of the histogram peaks bythe norm of each channel. Therefore, the normalized coordinates
of the peaks are stable to the changes in illumination color, scaling, rotation, partial occlusion, viewing direction, and
deformation. Test results on a database of diverse images show that the chromatic invariant yields excellent recognition
rate even when the illuminant color and geometric conditions varysubstantially .