08023159 cites 21 patents.

The present invention provides methods and apparatus for embedding an identifying pattern of visible speckles into the digitized image of each page of a document. A speckle is a cluster of black or white pixels. Speckles are printed as black speckles on the white paper, or conversely, as areas of missing black removed from the black text characters, called white speckles. The collective pattern of all embedded black and white speckles on a single document page is called a specklemark. A specklemark can survive contrast manipulations on photocopiers and binary rasterization done by fax scanning prior to data transmission. The random pattern of the black and white speckles visible in the digitized image of a document page can be detected automatically, and by systematically matching the detected pattern with those known to have been embedded into marked copies of a document page, a specific document copy can be identified. Methods for composing, embedding and detecting specklemarks are the subject of this patent.

Title
Marking images of text with speckle patterns for theft deterrence
Application Number
12/169786
Publication Number
8023159 (B2)
Application Date
July 9, 2008
Publication Date
September 20, 2011
Inventor
Frederick C Mintzer
Shrub Oak
NY, US
Gordon W Braudaway
Yorktown Heights
NY, US
Agent
Hoffman Warnick
Brian Verminski
Assignee
International Business Machines Corporation
NY, US
IPC
G06K 9/00
H04N 1/40
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