Patent ID: 6154567
Filing Date: 2000-11-28
Classification: G06K,G06T

Abstract:
A method for comparing a model image with a run-time image so as to provide a quantitative measure of image similarity, the method comprising:at train-time,extracting sample pixels of the model image so as to provide a pixel position and a gray value for each sample pixel of the model image;computing gray value differences between overlapping pairs of sample pixels of the model image;computing a compact binary representation for each overlapping pair;computing an expanded binary representation for each compact binary representation;associating a corresponding pixel position with each expanded binary representation to provide a model element; andgrouping all model elements together to provide a model, and at run-time,determining gray values at a plurality of selected pixel locations in a run-time image in accordance with pixel positions of the elements of the model;computing gray value differences between overlapping pairs of the selected pixels of the run-time image;computing a compact binary representation for each overlapping pair of the selected pixels of the run-time image;computing a run-time bit-expanded representation for each run-time compact binary representation;comparing each run-time bit-expanded representation with a corresponding model bit-expanded representation to provide a match count increment; andcombining all match count increments to provide a total match value.