Information embedding in document copies

• US 6,456,393 B1
• Filed: 08/18/1998
• Issued: 09/24/2002
• Est. Priority Date: 08/18/1998
• Status: Expired due to Term

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Bhattacharjya, Anoop K., Ancin, Hakan
• Primary Examiner(s): WALLERSON, MARK E
• Application Number:
  US09/136,161
• Time in Patent Office: 1,498 Days
• Field of Search: 358/1.12, 358/1.13, 358/1.9, 358/448, 358/452, 382/232, 382/181, 382/137, 382/306
• US Class Current: 358/1.9
• CPC Class Codes: G06V 30/40 Document-oriented image-based pattern recognition
• CPC Class Codes: H04N 1/32144 embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
• CPC Class Codes: H04N 2201/0091 Digital copier; digital 'photocopier' H04N2201/0093 and H04N2201/0094 take precedence
• CPC Class Codes: H04N 2201/3235 Checking or certification of the authentication information, e.g. by comparison with data stored independently
• CPC Class Codes: H04N 2201/3236 Details of authentication information generation
• CPC Class Codes: H04N 2201/327 which are undetectable to the naked eye, e.g. embedded codes

Abstract

A photocopier (10) scans a document and so modifies the resultant image as to embed in a resultant copy information that is visually imperceptible. To do so, it identifies regions (32, 33) that consist primarily of text-character parts. It embeds a message bitstream by selectively darkening the text pixels in such regions in accordance with the values of successive bits in the bitstream.

Claims