| 摘要 |
A method for inserting/extracting a watermark from printed documents and a system using the same are provided to offer a technology having a high practical value by securing a watermark insertion quantity enough to represent information of a user printing the document or other information needed for the document, and inserting the watermark into the document printed in a binary image. A watermark inserter(100) includes an image converter(110) converting the information into a format available in a printer driver, an encoder(120) transforming the information to be hidden into the watermark, an inserter(130) inserting the watermark into an image signal output from the image converter, and a printing part(140) printing a document image including the watermark. A watermark extractor(200) includes the image converter(210) converting the output document into a digital image, a preprocessor(220) processing the digital image into the format conveniently handled in a watermark extractor(230), the watermark extractor extracting watermark information from the document image, and a decoder(240) decoding the hidden information from the extracted watermark.
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