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. 03, 2001
Filed:
Apr. 15, 1998
Walter Bender, Auburndale, MA (US);
Daniel Gruhl, Cambridge, MA (US);
Massachusetts Institute of Technology, Cambridge, MA (US);
Abstract
A technique for embedding a tracking number as a series of bits in a printed image alters characteristic parameter values at a set of pseudo-random locations chosen for each bit in an embedding zone. The alteration markedly changes the expectation value of some linear combination of mathematical functions of the values at that set of locations. A marker bit encoded to a higher certainty than other bits in the string aids in orienting the zones in decoding. The tracking number is detected and identified by exploiting the behavior of sums of a large number of random variables, based on the Patchtrack approach.