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:
Jul. 14, 2009
Filed:
Apr. 04, 2003
T. S. Anthony Ho, Singapore, SG;
Jun Shen, Singapore, SG;
K. K. Andrew Chow, Singapore, SG;
W. M. Jeremiah Woon, Singapore, SG;
T. S. Anthony Ho, Singapore, SG;
Jun Shen, Singapore, SG;
K. K. Andrew Chow, Singapore, SG;
W. M. Jeremiah Woon, Singapore, SG;
Datamark Technologies Pte Ltd, Singapore, SG;
Abstract
The invention provides a method and apparatus for watermarking a document, the method comprising: associating the document with an identification number; generating () a first set of numbers using a seed for the number generation comprising or derived from the identification number; applying a transform () to at least a portion of an image of the document to form a transform of the image; defining a second set of numbers comprising transform coefficients from the transform of the image; forming a modified second set of numbers based on the first set and the second set; substituting the modified second set for the second set in the transform of the image to form a modified transform (); and applying an inverse () of the transform to the modified transform to thereby produce a modified image of the document; whereby the modified image of the document or an output of the modified image constitutes the watermarked document.