Patent ID: 7995246
Filing Date: 2011-08-09
Classification: G06T,G07B,G07D

Abstract:
1. A method of determining whether a printed-image-under-examination (PIUE) is a copy of an original printed image, 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) transforming the pixel data in at least some of the data blocks to obtain transform domain data by applying at least one of a Fourier transform, a fast Fourier transform, a discrete cosine transform (DCT) and a wavelet transform to the pixel data in the at least some of the data blocks to obtain the transform domain data; (d) applying a watermark detecting operation to the transform domain data for respective ones of the data blocks to generate recovered watermark data; and (e) determining a correlation between the recovered watermark data for at least some of the data blocks and a brightness of said data blocks.