An identification code signal is impressed on a carrier to be identified (such as an electronic data signal or a physical medium) in a manner that permits the identification signal later to be discerned and the carrier thereby identified. The method and apparatus are characterized by robustness...http://www.google.fr/patents/US5710834?utm_source=gb-gplus-shareBrevet US5710834 - Method and apparatus responsive to a code signal conveyed through a graphic image
Method and apparatus responsive to a code signal conveyed through a graphic ...
