Patent ID: 7446891
Filing Date: 2008-11-04
Classification: G06T,H04N

Abstract:
1. A method of determining whether a printed-image-under-examination (PIUE) is a original printed image, with a fragile watermark the method comprising: (a) scanning the PIUE to generate scanned image data, the scanned image data comprising pixel data, the pixel data comprising gray scale values and representing the PIUE as a set of scanning pixels; (b) forming a plurality of data blocks from the scanned image data, each data block consisting of pixel data which corresponds to a respective region of the PIUE; (c) determining for each of the data blocks an average value of the pixel data in the data block; (d) determining for each of the data blocks an index value based on the average value of the pixel data in the data block; (e) for each data block, calculating a difference between the index value for the data block and a value that represents a target value for a corresponding block of pixel data that was used to generate the original printed image, and (f) determining whether the PIUE is the original printer images with the fragile watermark.