Tampering detection apparatus and tampering detection method for printed document

Abstract

A printed document tampering detection apparatus 120 for detecting tampering with a printed document having embedded in the background thereof at least part of the document contents as an electronic watermark comprises a reader unit 127 that reads the printed document and generates an image of the printed document, a watermark detection unit 125 that detects document contents from the electronic watermark embedded in the printed document and an output unit 123 that brings up a first display frame 310 for the printed document image and a second display frame 320 for the document contents in such a manner that a ready comparison thereof is enabled. The user is able to visually compare the contents of document information 105 and the printed document image 126 and retrieve the initial unadulterated information. Thus, the tampering does not result in any data loss.

Dependencies are inferred from the claim text.