METHOD AND SYSTEM FOR RECOGNIZING SECURITY DOCUMENTS

A document is analyzed to determine whether it is a banknote or the like, by reference to image data corresponding to the document. Two analysis techniques may be used, one based on detection of a visible pattern characteristic of a security document, the other based on detection of a steganographic digital watermark characteristic of a security document. If either characteristic is found, the image is flagged, and appropriate anti-counterfeiting steps may be taken. Detection of the visible pattern can be performed using a series of successively more rigorous tests. If the image fails a test, successive testing steps can be skipped, speeding the process. Hough transform-based pattern recognition techniques are used in some embodiments. Provision of both a visible pattern detector and a watermark detector in a single apparatus enhances detection reliability, while permitting various implementation efficiencies.