| 摘要 |
<P>PROBLEM TO BE SOLVED: To make it difficult for a user who receives the same material to succeed in a collusion attack. <P>SOLUTION: In a watermark system, an encoded data processing apparatus is provided for creating a watermarked copy of an original material item by introducing one code word in a prescribed set to a copy of an original material item, and the set of code words are generated by shifting a first code word in the manner of circulation. A correlative value of all the code words generated by shifting the first code word is calculated by using a Fourier transformation correlator to remarkably shorten the time required for detecting a code word in the watermarked material item. The watermark system, is particularly effective for specifying a creation source of a pirate edition copy of a video material produced by photographing watermarked images while using a camcorder in a movie theater, for example. <P>COPYRIGHT: (C)2004,JPO |
