METHOD FOR INSERTING GUILLOCHE PATTERNS, METHOD FOR EXTRACTING GUILLOCHE PATTERNS, AUTHENTICATION METHOD FOR SAID GUILLOCHE PATTERNS AND IMPLEMENTATION DEVICES

摘要

The invention relates to a method for inserting guilloche patterns on a document, each guilloche pattern being able to encode variable alphanumeric data ensuring a different appearance to each guilloche pattern so as to secure said document, the method comprising an operation (300-600) for determining an insertion intensity of each previously generated guilloche pattern (100) according to a medium gray level of the document adjacent said guilloché pattern.;The invention also relates to a device implementing this insertion method.;The invention also relates to a method for extracting the guilloche patterns (601-608) from a secure document (600) that can be degraded, the method comprising the following operations: -determining (710) a contrasts map (c) of at least a portion of the secure document including the guilloche patterns; - identification (720), on this map of the contrasts, of an optimal percolation trajectory; and extraction (730) of the optimal percolation trajectory, said trajectory corresponding to the guilloche pattern.;The invention further relates to a method for authenticating the guilloche patterns of a secure document that may be degraded, comprising: - the previous extraction operations, and an operation (740) for comparing each extracted guilloche pattern with a corresponding theoretical guilloche pattern.