Special document discrimination system

摘要

In a system for determining whether a document is identical to a predetermined reference, an image of the document is analysed to determine whether either the distances between a plurality of fine lines on the document is uniform eg due to planographic printing using a halftone screen, or there are a predetermined number of fine lines of a predetermined width eg due to intaglio printing. Thus it is possible to determine whether an original that is about to be duplicated is a banknote and prevent successful duplication.