Patent ID: 9582953
Date: 2017-02-28
CPC Classifications: G01N,G07D,G07F

Claim:
1. A method for checking a value document, with the following steps of: detecting in spatially resolved fashion measuring values (Ii, Ij) in a plurality of different measuring points on the value document which are distributed over the value document two-dimensionally; forming a two-dimensional network of nodes (Ki, Kj), wherein each node corresponds to at least one measuring point on the value document, and allocating the measuring value detected in the respective measuring point to the node corresponding to this measuring point; creating two additional nodes arranged on mutually opposing sides of the two-dimensional network, and connecting the two additional nodes with the two-dimensional network of nodes (Ki, Kj), wherein one of the additional nodes is a source node (KQ) forming a source for a flow through the network, and the other one is a sink node (KS) forming a sink for a flow through the network; determining respectively one capacity value for each pair of two adjacent nodes (Ki, Kj) of the network, said capacity value being a measure of the maximally possible flow between the two adjacent nodes, by mutually comparing the measuring values (Ii, Ij) of respectively two adjacent nodes (Ki, Kj) of the network, ascertaining respectively one capacity value (cij) for each of the pairs of adjacent nodes on the basis of this comparison and allocating the respective capacity value (cij) to a connecting line between the two adjacent nodes (Ki, Kj) of the respective pair of adjacent nodes whose measuring values have been mutually compared; computing the maximally possible flow from the source node (KQ) through the network to the sink node (KS) on the basis of the ascertained capacity values (cij); classifying the value document, in particular in view of the presence of a composed forgery, as suspected of forgery or not suspected of forgery in dependence on the computed maximally possible flow through the network.