METHOD FOR DETECTING ALTERATIONS IN PRINTED DOCUMENT USING IMAGE COMPARISON ANALYSES
First Claim
1. A method implemented in a data processing apparatus for detecting alterations between an original image and a target image, the original and target images being binary bitmap images, the method comprising:
- (a) extracting connected image components from the original and target images;
(b) calculating a centroid for each of the extracted connected image components in the original and target images;
(c) comparing all centroids of the original image and all centroids of the target image to determine whether each centroid of the original image has a matching centroid of the target image, and whether each centroid of the target image has a matching centroid of the original image;
(d) for each centroid of the original image that does not have a matching centroid in the target image, identifying the corresponding connected image component of the original image as a deleted connected image component;
(e) for each centroid of the target image that does not have a matching centroid in the original image, identifying the corresponding connected image component of the target image as an added connected image component;
(f) for each pair of matching centroids of the original and target images, comparing a pair of sub-images of the original and target images containing connected image components corresponding to the centroids to detect alterations; and
(g) generating an alteration map which indicates any deleted or added connected image components identified in steps (d) and (e) and any alterations detected in step (f).
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Accused Products
Abstract
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.
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Citations
20 Claims
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1. A method implemented in a data processing apparatus for detecting alterations between an original image and a target image, the original and target images being binary bitmap images, the method comprising:
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(a) extracting connected image components from the original and target images; (b) calculating a centroid for each of the extracted connected image components in the original and target images; (c) comparing all centroids of the original image and all centroids of the target image to determine whether each centroid of the original image has a matching centroid of the target image, and whether each centroid of the target image has a matching centroid of the original image; (d) for each centroid of the original image that does not have a matching centroid in the target image, identifying the corresponding connected image component of the original image as a deleted connected image component; (e) for each centroid of the target image that does not have a matching centroid in the original image, identifying the corresponding connected image component of the target image as an added connected image component; (f) for each pair of matching centroids of the original and target images, comparing a pair of sub-images of the original and target images containing connected image components corresponding to the centroids to detect alterations; and (g) generating an alteration map which indicates any deleted or added connected image components identified in steps (d) and (e) and any alterations detected in step (f). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A computer program product comprising a computer usable medium having a computer readable program code embedded therein for controlling a data processing apparatus, the computer readable program code configured to cause the data processing apparatus to execute a process for detecting alterations between an original image and a target image, the original and target images being binary bitmap images, the process comprising:
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(a) extracting connected image components from the original and target images; (b) calculating a centroid for each of the extracted connected image components in the original and target images; (c) comparing all centroids of the original image and all centroids of the target image to determine whether each centroid of the original image has a matching centroid of the target image, and whether each centroid of the target image has a matching centroid of the original image; (d) for each centroid of the original image that does not have a matching centroid in the target image, identifying the corresponding connected image component of the original image as a deleted connected image component; (e) for each centroid of the target image that does not have a matching centroid in the original image, identifying the corresponding connected image component of the target image as an added connected image component; (f) for each pair of matching centroids of the original and target images, comparing a pair of sub-images of the original and target images containing connected image components corresponding to the centroids to detect alterations; and (g) generating an alteration map which indicates any deleted or added connected image components identified in steps (d) and (e) and any alterations detected in step (f). - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification