METHOD FOR DETECTING ALTERATIONS IN PRINTED DOCUMENT USING IMAGE COMPARISON ANALYSES

A document alteration detection method compares a target image with an original image using a two-step process. In the first step, the original and target images are divided into connected image components and their centroids are obtained, and the centroids of the image components in the original and target images are compared. Each centroid in the target image that is not in the original image is deemed to represent an addition, and each centroid in the original image that is not in the target image is deemed to represent a deletion. In the second step, sub-images containing the image components corresponding to each pair of matching centroids in the original and target images are compared to detect any alterations.