ELECTRONIC WATERMARK EMBEDDING APPARATUS AND METHOD THEREOF, AND ELECTRONIC WATERMARK EXTRACTING APPARATUS AND METHOD THEREOF

摘要

PROBLEM TO BE SOLVED: To solve the problem that photographing a printed image having an electronic watermark embedded therein causes distortion, resulting in the difficulty in correctly detecting the electronic watermark.

SOLUTION: A photographing unit 30 photographs an image obtained by sticking a frame around the periphery of an original image having an electronic watermark embedded therein and printing it. A lens distortion correcting unit 32 corrects distortion generated in the photographed image. A feature point extracting unit 34 extracts a plurality of feature points arranged with a predetermined interval in the frame of the photographed image after the lens distortion correction. An image shape/size determining unit 36 determines the shape and the actual size of an original image region on the basis of the arrangement of the plurality of feature points. A transparent distortion correction unit 38 uses a feature point template matching the shape and actual size of the original image region to detect positional deviation of each of the feature points in the frame of the photographed image, thereby correcting the transparent distortion generated in the original image region. A watermark extracting unit 40 extracts watermark information X from the corrected original image region.

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