| 摘要 |
PROBLEM TO BE SOLVED: To enable reduction of throughput at the time of signal detection by a method wherein a signal can be resurrected in the case that distortion exists in an input image which is caused by rotation of a paper etc. when a signal is detected, so that spin compensation of the image is unnecessary. SOLUTION: In this watermark padding method, dots are regularly arranged as a background of a document, a dot pattern different in rule of arrangement is inserted in the regularly arranged dots, and information is applied to rule of arrangement of a dot pattern. The dot pattern is constituted including at least first, second and third dots (a starting point dot, a level reference dot, a modulation dot). A value is set to the dot pattern in accordance with a characteristic value which is fixed by relative positional relationship of the first, the second and the third dots. The characteristic value is inner product of a vector wherein the third dot is made a starting point, the first dot is made an end point, and a vector wherein the third dot is made a starting point and the second dot is made an end point. COPYRIGHT: (C)2004,JPO
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