Abstract
Recent works have demonstrated that the direct use of grey levels for image matching and indexing allows building very powerful systems. The present paper tries to enlarge these results to the case of color images. First, it presents a small abstract about photometry and cameras, which allows justifying the choice of a color representation system. Then it presents, evaluates, compares several illumination models, and discusses image normalization techniques. Finally, the paper presents a set of color invariants for image matching and indexing.