Patent ID: 9405991
Filing Date: 2016-08-02
CPC Classification: G06F,G06K,G06T,H04M

Claim Text:
1. An image processing method for comparing images to identify a reference image that best matches a test image, the method including the acts: generating a reference image histogram for each of plural reference images, each reference image histogram comprising a set of plural bins where each bin has a value, at least one of said reference image histograms including a bin with a zero value and a bin with a non-zero value; generating a test image histogram for a test image, the test image histogram comprising a set of plural bins where each bin has a value, the test image histogram including a bin with a zero value and a bin with a non-zero value; wherein there is a correspondence between bins in the reference image histograms and bins in the reference histogram, so that each bin in a reference image histogram corresponds to a counterpart bin in the test image histogram, thereby defining pairs of test-reference bins, a first of said pairs having a zero value in the reference histogram bin, and a second of said pairs having a zero value in the test histogram bin; scaling each bin value of the test image histogram by a common scaling factor, yielding a scaled test histogram, said scaling reducing sensitivity of the image comparison method to difference in sizes between the test image and the reference images; and computing a first comparison metric for each of the reference image histograms, said computing including summing plural factors, where each factor is based on one of said pairs of bins, said computed first comparison metrics serving to indicate which of said reference image histograms most closely corresponds to the scaled test image histogram; wherein the factor based on said first pair of bins makes a contribution of zero to said summing due to the zero value in the reference histogram bin, but the factor based on said second pair of bins makes a non-zero contribution to said summing, despite the zero value in the test histogram bin.