Method and system for detecting a geometrically transformed copy of an image

Abstract

A method for detecting a geometrically transformed copy of content in at least a portion of an image, comprises the steps of: (a) providing first and second digital images; (b) searching for objects of interest within each digital image; (c) identifying pairs of corresponding objects of interest in the digital images, wherein each pair of corresponding objects of interest comprises a located object of interest in the first digital image and a corresponding located object of interest in the second digital image that corresponds to the located object of interest in the first image; (d) locating feature points on each located object of interest in each digital image; (e) matching feature points on the located object of interest in the first digital image to the feature points on the corresponding object of interest in the second digital image, thereby generating a set of correspondence points for each image; (f) determining parameters of a geometric transformation that maps the set of correspondence points in the first digital image into the set of correspondence points in the second digital image; (g) transforming the first digital image according to the parameters of the geometric transformation determined in step (f); and (h) detecting regions of similarity between the content of the transformed first digital image and the second digital image, thereby determining if the second image contains a region that is a geometrically transformed copy of a region in the first image.