| 摘要 |
PROBLEM TO BE SOLVED: To embed watermark information to a color document image by appropriately imparting a background in accordance with an area color of the color document image and to surely detect a watermark from the printed matter or the copy of the color document image independently of the area colors. SOLUTION: An embedding area in which a background pattern can be embedded from a color image 223 is extracted. At least one of a color and a shape of the background pattern is determined depending on the area color of the embedding area. Since luminance of the color areas 301, 302 and 304 exceeds a threshold value, a background pattern image A is adopted for a plurality of embedding areas belonging to these color areas. Since luminance of a color area 303 is below the threshold value, on the other hand, a background pattern B is adopted to a plurality of embedding areas belonging to the color area 303. COPYRIGHT: (C)2008,JPO&INPIT
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