Canon Kabushiki Kaisha

Roger David Butler

Junya Arakawa

Alan Gordon Doubleday

Neil Yager

Matthew Christian Duggan

Disclosed is a method () for identifying potential tamper in a candidate document having content affected by noise. A candidate content value for each of a plurality of sub-regions of the candidate document and an original content value for each of a plurality of sub-regions of a corresponding original document are determined. The content values are desirably determined based on at least one characteristic of the content in the corresponding sub-region. The candidate content values () are associated with the corresponding original content values and a distribution of the candidate content values based on the corresponding original content values is determined. The method characterizes () the noise in the candidate document by determining an expected content value range based on the spread of a selected part of the distribution of candidate content values. The method can then identify () candidate content values outside the expected content value range as potential tamper.

Dynamic thresholds for document tamper detection

A method of authenticating a first document () including content () and a barcode (). The barcode () comprising barcode elements each having a predetermined form. A plurality of the barcode elements of the barcode are detected in a representation of the first document (). A visual difference between each of the detected barcode elements and the predetermined form of the barcode element is determined. The barcode () is decoded to determine a second document. The first document () and the second document are compared based on the determined visual difference, in order to authenticate the first document ().

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Abbotsford, Australia

Roger David Butler