The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 29, 2003
Filed:
Mar. 15, 1999
Viresh Ratnakar, Sunnyvale, CA (US);
Seiko Epson Corporation, Tokyo, JP;
Abstract
A steganographic method embeds hidden information like digital watermarks and digital fingerprints into an image by applying one or more zero-mean patches to a digital signal that conveys the image. Each zero-mean patch comprises elements having an average value substantially equal to zero. A printer tracking system is implemented by selecting a plurality of zero-mean patches according to a string of bits representing a printer serial number, and modifying printer control signals to embed the plurality of patches in each of a number of virtual cells within the image to be printed. The offset of the virtual cells with respect to the boundaries of the image and the location of the patches within each virtual cell are established in pseudo-random fashion. The printer tracking system further includes a technique for subsequently detecting the printer serial number by scanning the printed image and running a detection algorithm on the scanned data to recover the string of bits embedded in the zero-mean patches.