A method corrects a color image by avenging at least two color channels in regions near the minimum of histograms of the at least two color channels; selecting the smallest of the avenge color values as a black point; averaging at least two color channels in regions near the maximum of the histograms...http://www.google.fr/patents/US7057768?utm_source=gb-gplus-shareBrevet US7057768 - Automatic color balance
