Unsupervised corrections of unknown chromatic dominants using a Brownian-path-based Retinex algorithm

An experimental analysis of chromatic equalization based on a new implementation of the Retinex algorithm is presented. The experiments are carried out on a colored Mondrian patchwork illuminated with different commercial light sources and on synthetic images generated with a photometric ray tracer using different illuminants. Regarding the Mondrian patchwork, the spectral characteristics of the bulbs and the reflected light from each patch are measured using a commercial spectrometer. From the measured data, synthetic images of the patchwork with different illuminants are created and processed by the Retinex algorithm. The chromatic correction capabilities of the Retinex implementation have been measured and compared with unfiltered values and with the results of another Retinex implementation and classic color equalization algorithms. Results show that Retinex performs an unsupervised color correction without requiring any information about the spectral composition of the illuminant. © 2003 SPIE and IS&T. [DOI: 10.1117/1.1584051]