The invention determines the degree of similarity between a target image
and each of a plurality of reference images. The measure used for the
degree of similarity between images is based on the human perceptive
system, so that images that appear to a human to be similar in color have
a higher similarity measure than images that appear to a human to be
dissimilar in color. Each of the most populous colors of each partition
of the target image is associated with a color in a corresponding
partition of the reference image that is closest to the target image
color. The similarity measure is based on the number of occurrences of
each of these associated colors in the corresponding partitions, as well
as the color difference between these associated colors. Thus, images
that have similar, albeit not identical, colors, will have a higher
similarity measure than images that have dissimilar colors. In a
preferred embodiment, color difference is determined based upon the CIE
luminance-chrominance color space. Also, in a preferred embodiment, the
target image color is quantized into a set of discrete colors that are
based upon the predominant colors in the reference images.