Patent Document ID: 6014453
Application ID: 08660409
Patent Flag: 1

Claim One:
1. A counterfeit detecting method to generate a counterfeit probability data representing a probability that an attempt is being made to counterfeit a document, comprising the steps of: comparing an input image pattern of a document with a characteristic pattern peculiar to a non-reproducible image of a document which may not be reproduced to generate a first comparison data with respect to said characteristic pattern peculiar to a non-reproducible image; and comparing said input image pattern with a set of altered patterns which correspond to a set of results of tampering with said non-reproducible image to generate a second comparison data with respect to said altered patterns, said set of altered patterns is within a range of alterations which cannot fool an electrical eye but do not arouse suspicion when viewed by a human eye, wherein said first comparison data and said second comparison data are used to determine said counterfeit probability data and wherein said counterfeit probability data is obtained by plugging into a specified algorithm a result of sorting goodness of fit which is previously obtained by applying a predetermined threshold to goodness of fit of said input image pattern with respect to said characteristic pattern peculiar to said non-reproducible image and said set of altered patterns respectively.