A printed object, such as an item of postal mail, a book, printed advertising, a business card, product packaging, etc., is steganographically encoded with plural-bit data. When such an object is presented to an optical sensor, the plural-bit data is decoded and used to establish a link to an internet...http://www.google.com/patents/US6542927?utm_source=gb-gplus-sharePatent US6542927 - Linking of computers based on steganographically embedded digital data
