US 6,983,056 B1
Method and device for embedding and detecting watermarking information into a black and white binary document image
Tomio Amano, Yokohama (Japan)
Assigned to International Business Machines Corporation, Armonk, N.Y. (US)
Filed on Jul. 21, 2000, as Appl. No. 9/621,567.
Claims priority of application No. 11-223490 (JP), filed on Aug. 06, 1999.
Int. Cl. G06K 9/00 (2006.01)
U.S. Cl. 382—100 12 Claims
OG exemplary drawing
 
1. An embedding method for embedding additional watermarking information into data representing text information as a black and white binary document image, comprising the steps of:
detecting a text image area;
splitting the detected text image area into two or more subblocks;
dividing the two or more subblocks into two or more groups;
extracting features for each of the two or more groups;
modifying the extracted features based on the additional watermarking information by increasing the extracted features of one group and decreasing the extracted features of another group; and,
embedding the modified features into each of the two or more groups as the additional watermarking information, wherein the embedded additional watermark information is provided into said data representing text information in a manner that is not visually recognizable by human perception.