Document verification system, document verification method, document verification program and recording medium

摘要

PPROBLEM TO BE SOLVED: To detect the fraudulent alteration of document with high accuracy, even when causing ink blotting, toner scattering, distortion and noise during printing/scanning, or the like. PSOLUTION: A document verification system 111 acquires a feature value of a plurality of areas of original document data from watermark data, receives a plurality of candidates of an n-value-ized threshold, uses the plurality of candidates for the n-value-ized threshold to n-value-ize the pixel value of a pixel included in a plurality of areas corresponding to the plurality of areas of the original document data of image data of a verification target document, acquires a feature value for comparison calculated on the basis of the n-value-ized pixel value, defines a feature value for comparison whose difference from the feature value of the original document data is the smallest as a determined feature value in each corresponding to area, compares the n-value-ized threshold used when acquiring the determined feature value between areas adjacent to each other, and when the compared difference is larger than a predetermined value, determines that the verification target document is falsified in the area. PCOPYRIGHT: (C)2011,JPO&INPIT