초록 ▼

Line art on a banknote or other security document is slightly changed to effect the encoding of plural-bit digital data (i.e. the banknote is digitally watermarked). When such a banknote is thereafter scanned, the resulting image data can be recognized as corresponding to a banknote by detection of

Line art on a banknote or other security document is slightly changed to effect the encoding of plural-bit digital data (i.e. the banknote is digitally watermarked). When such a banknote is thereafter scanned, the resulting image data can be recognized as corresponding to a banknote by detection of the encoded data. (Alternatively, the image data can be recognized as corresponding to a banknote by machine detection of other forms of watermarking, or by reference to visible structures characteristic of banknotes.) In response to detection of a banknote, the detecting apparatus (e.g., a scanner, photocopier, or printer) can intervene so as to prevent or deter counterfeiting. For example, the apparatus can interrupt a copying operation, and display a message reminding the operator that it is illegal to reproduce currency. Another option is to dial a remote service and report the attempted reproduction of a banknote. Yet another option is to permit the copying, but to insert forensic tracer data (e.g. steganographically encoded binary data) in the resultant copy. The tracer data can memorialize the serial number of the machine that made the copy and/or the date and time the copy was made. To address privacy concerns, such tracer data is not normally inserted in photocopied output, but is so inserted only when the subject being photocopied is detected as being a banknote.

대표청구항 ▼

1. A method of marking a financial instrument to convey plural binary bits, thereby facilitating machine-recognition thereof, the financial instrument having a visible structure formed thereon, the method being characterized in that the marking is not apparent to human observers of the document, yet

1. A method of marking a financial instrument to convey plural binary bits, thereby facilitating machine-recognition thereof, the financial instrument having a visible structure formed thereon, the method being characterized in that the marking is not apparent to human observers of the document, yet can be detected from image data generated by visible light scanning of the financial instrument.2. The method of claim 1 wherein the visible structure comprises at least one of a seal and logo.3. The method of claim 2 wherein the marking comprises a background pattern formed over at least a portion of the financial instrument.4. The method of claim 1 wherein the financial instrument comprises a paper document.5. The method of claim 1, wherein the financial instrument comprises legal tender.6. The method of claim 1, wherein the financial instrument comprises at least one of a credit card, a debit card and an ATM card.7. A method of marking a security document to convey plural bit information, thereby facilitating machine-recognition thereof through detection of image data generated by visible light scanning of the security document, the marking including a visible pattern formed over at least a portion of the security document, wherein the pattern does not betray the existence of the plural bit information to casual human observers of the document.8. The method of claim 7, wherein the security document comprises a financial instrument.9. The method of claim 7 wherein the visible pattern comprises a background pattern.10. The method of claim 7 wherein the visible pattern comprises a noise-like pattern.11. The method of claim 7 wherein the plural bit information is redundantly marked on the security document.12. The method of claim 7 wherein the visible pattern comprises artwork.