Watermark information embedding and detection method and apparatus of the black-and-white binary document image

摘要

PROBLEM TO BE SOLVED: To obtain a method and a device for embedding and detecting of watermark information in a black-and-white binary document picture which can embed even a document picture of paper, which is ordinarily black-and-white binary data, with watermark information and stably detect the embedded information. SOLUTION: A text area is detected from the document picture, and the feature quantity of the detected text area is increased or reduced, or the detected text area is divided into plural small sections and each small section is divided into two or more groups and the feature quantity of each group is increased or reduced, so that the document picture with watermark information is embedded. At the time of detection of a watermark, integrated values of feature quantities obtained from respective groups are compared to detect the watermark information.