US 6,449,377 · Granted 2002-09-10
Methods and systems for watermark processing of line art images
Line art on banknotes and the like is subtly altered to steganographically encode plural-bit digital information. For example, the lines' widths or spacings can be locally changed so as to slightly modulate the apparent luminance of the document. The encoded information can be decoded using suitably-equipped processing equipment and used to identify a document as a banknote. Various anti-counterfeiting actions can then be taken.
Patent details
- Publication number
- US 6,449,377
- Filing date
- 1998-05-06
- Grant date
- 2002-09-10
- Assignee
- Digimarc Corporation
- Inventor(s)
- RHOADS GEOFFREY B.
- CPC class
- H04N1/00846
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