Unsupervised Color Correction for Digital Photographs

The paper describes a reliable and rapid method for detecting and removing a color cast (i.e. a superimposed dominant color) in a digital image without any a priori knowledge of its semantic content. A multi-step algorithm classifies the input images as having no cast, evident cast, ambiguous cast, or intrinsic cast (images presenting a cast due to a predominant color that must be preserved). If an evident or ambiguous cast is found, a cast remover step, a modified version of the white balance algorithm, is then applied in the two cases of evident or ambiguous casts. The method we propose has been tuned and tested with positive results on a data set of over 650 images.