Methods and systems for watermark processing of line art images
AssigneeDigimarc Corporation
InventorGeoffrey B. Rhoads
Life of this patent
Estimating the term…
Abstract
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.
Claims15
A method of embedding binary data in a banknote, comprising:
- providing nominal line art for the banknote;
- defining a plurality of virtual regions in at least an excerpt of said line art, each of said regions having an area less than 0.001 square inches;
- and
- changing a luminance value of plural of said regions to embed binary data therein,
- wherein said changes are not apparent to a human viewer of the banknote, yet can be detected from visible light scan data corresponding to said banknote.
A method for encoding plural-bit digital data in a banknote, to facilitate later machine identification of the banknote, comprising:
- receiving initial banknote artwork including plural artwork elements;
- changing the position o r dimension of certain of said artwork elements to steganographically encode said plural-bit digital data, yielding adjusted banknote artwork;
- and
- printing a banknote corresponding to said adjusted banknote artwork.
A method of watermarking a banknote to convey auxiliary data, the banknote including an element having a contour, characterized in that the method includes spatially shifting the location of said contour.
Dependencies are inferred from the claim text.