06807634 is referenced by 38 patents and cites 3 patents.

A digital watermarking method encodes different pairs of watermarks into each of a plurality of images offered for use by a vendor. The watermarks in each pair are derived from two separate collections of watermarks and sufficiently different so as to prevent false positives. Because each pair of watermarks is assigned to a different customer relative to a particular image, unauthorized use of a digital image sold to a customer may be determined by locating the associated pair of watermarks assigned to the customer in the image. Collusion detection is also realized by forming each pair of masks from sub-collections of masks which are detectable in an image formed by combining the same images sold to one or more customers.

Title
Watermarks for customer identification
Application Number
9/449618
Publication Number
6807634 (B1)
Application Date
November 30, 1999
Publication Date
October 19, 2004
Inventor
Chai W Wu
Poughquag
NY, US
Charles P Tresser
Mamaroneck
NY, US
James B Shearer
Ossining
NY, US
Frederick C Mintzer
Shrub Oak
NY, US
Marco Martens
Chappaqua
NY, US
Gordon W Braudaway
Yorktown Hts.
NY, US
Agent
Whitham Curtis & Christofferson P C
US
Agent
Stephen C Kaufman
US
Assignee
International Business Machines Corporation
NY, US
IPC
H04L 9/00
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