Auto White Balance Using the Coincidence of Chromaticity Histograms

This paper presents a simple and robust auto white balance algorithm using the coincidence of chromaticity histograms. After analyzing the relationship between the coincidence of the color histogram and color constancy, the overlap area of chromaticity histograms that keep chromaticity of color images but not the effect of luminance existing in the color histogram is employed to estimate the correct illuminant in scenes. When the overlap reaches the maximum, correspondingly the respective gain coefficients of color channels can be derived to achieve the white balance of the camera. Through numerous experiments and evaluations based on the processing of real world images, the proposed coincidence of chromaticity histograms algorithm achieves the outstanding performance comparing to other algorithms. Furthermore, the simplicity, easy implementation and robustness to the luminance make it flexibly apply to the vision system of the autonomous robot running outdoor.