Method and apparatus for embedding identification codes in printed documents.

摘要

A method and apparatus (1203, 1403) for embedding identification information in documents. The present invention embeds information in each copy of a document (1207, 1407) such that a particular copy of the document is distinguishable from all other copies of the same document. Additionally, this embedded information (1209, 1301, 1409) is designed to remain intact even if the original is copied. A method and apparatus is also disclosed to embed verification information in a printed document (1207, 1407) such that modification to the text subsequent to printing is detectable. <IMAGE>