Abstract: This disclosure generally relates to identifying objects by comparing their histograms. In aspect, the histograms of different color resolutions are constructed for each image and each compared to a corresponding histogram of another image. The results of the comparisons are combined to obtain an indicator of the difference between the color contents of the images and can be used to determine whether the images match each other. In another aspect, the color space is divided unevenly for each histogram, with the portions of the color space corresponding to white or gray being more finely divided than the portions corresponding to more saturated colors.