A Flexible Auto White Balance Based on Histogram Overlap

Auto white-balance plays a very important role in computer vision, and also is a prerequisite of color processing algorithms. For keeping the color constancy in the real-time outdoor environment, a simple and flexible auto white balance algorithm based on the color histogram overlap of the image is presented in this paper. After looking at a numerous images under different illuminance, an essential characteristic of the white-balance, the color histogram coincidence, is generalized as the basic criterion. Furthermore the overlap area of the color histogram directly reflects this coincidence, namely, when the overlap area of the color histogram reaches the maximum, the respective gain coefficients of color channels can be derived to achieve the white-balance of the camera. Through the subjective and objective evaluations based on the processing of real world images, the proposed histogram overlap algorithm can not only flexibly implement the auto white-balance of the camera but also achieve the outstanding performance in the real-time outdoor condition.