Finding Waldo, or focus of attention using local color information

A method is presented to locate an object in a color image, or more precisely, to select a set of likely locations for the object. The model is assumed to be of known color, which permits the use of color-space processing. A new method is presented, which exploits more information than the previous backprojection algorithm of Swain and Ballard at a competitive complexity. The new algorithm is based on matching local histograms with the model, instead of directly replacing pixels with a confidence that they belong to the object. It is proved that a simple version of this algorithm degenerates into backprojection in the worst case. The authors show how to estimate the scale of the model. The use of co-occurrence histograms is proposed to deal with cases where important color variations can be expected