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, 2008
Filed:
Mar. 16, 2001
Applicants:
Sheng Huang, Singapore, SG;
Jian Kang Wu, Singapore, SG;
Inventors:
Sheng Huang, Singapore, SG;
Jian Kang Wu, Singapore, SG;
Assignee:
Trustcopy Pte Ltd., Singapore, SG;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G09C 3/08 (2006.01); G09C 3/00 (2006.01); H04L 15/34 (2006.01); H04L 9/00 (2006.01); B42D 15/00 (2006.01); G06K 15/00 (2006.01); H04N 1/40 (2006.01);
U.S. Cl.
CPC ...
Abstract
A multiple-layered watermark is generated to be placed on document, to protect against counterfeiting and forgery. Hidden information embedded into each of the watermark's layers is only detectable by using a corresponding decoder. Because of the multiple-layered structure, it is difficult to reverse engineer the optical watermark. The generalized watermark structure significantly increases the 'key space' of the decoder.