| 摘要 |
<P>PROBLEM TO BE SOLVED: To determine the presence or absence of line-spacing watermark information embedded in a document at a high speed. Ž<P>SOLUTION: In steps S203-S205, line spacing values in a document image are extracted and a variance is calculated for fluctuations in the line spacing values. In a step S206, when the calculated variance is higher than a preset threshold value set previously in a step S201, the document image is determined as having line-spacing watermark information embedded therein. Such use of the variance in the line spacing values enables high-speed determination of the presence or absence of line-spacing watermark information. At this time, it is possible to further speed up the determination by using only some line spacing values in the document, instead of using all line spacing values. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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