Patent ID: 8467605

Claim:
A method performed by one or more processes executing on a machine, the method comprising: accessing a first image having values in M color channels for each of a plurality of points within the first image, where the quantity M of the color channels is M≧3; generating a first pseudo-color image at least in part by applying histogram-equalization transformations to the values in N color channels from among the M color channels of the first image, where 2≦N≦M, such that the generated first pseudo-color image is invariant to both (i) illumination conditions of a scene depicted in the first image and (ii) response of an imaging device that acquired the first image; generating an N-dimensional color histogram of the first pseudo-color image; identifying a match to the first image at least in part by accessing a second image having values in the N color channels for each of a plurality of points within the second image; generating a second pseudo-color image at least in part by applying a histogram-equalization transformation to the values in the same N color channels of the second image used to generate the first pseudo-color image, such that the generated second pseudo-color image is invariant to both (i′) illumination conditions of another scene depicted in the second image and (ii′) response of another imaging device that acquired the second image; generating an N-dimensional color histogram of the second pseudo-color image; comparing the N-dimensional color histogram of the first pseudo-color image with the N-dimensional color histogram of the second pseudo-color image to determine whether the N-dimensional color histograms of the first and second pseudo-color images are similar; in response to determining that the N-dimensional color histogram of the second pseudo-color image is similar to the N-dimensional color histogram of the first pseudo-color image, identifying the second image as the match to the first image; and in response to determining that the N-dimensional color histogram of the second pseudo-color image is dissimilar to the N-dimensional color histogram of the first pseudo-color image, identifying the second image as a mismatch to the first image.