ELECTRONIC WATERMARK DETECTING APPARATUS AND METHOD THEREOF

摘要

PROBLEM TO BE SOLVED: To provide an electronic watermark detecting apparatus for more accurately detecting watermark information weakened by attacks such as image segmentation and scaling without an increase in the computation amount and in the circuit scale.

SOLUTION: The electronic watermark detecting apparatus comprises: an extraction unit 10 for extracting a signal of a prescribed frequency component from a watermark embedded image; first orthogonal transforming units 11A and 11B for calculating an orthogonal transformation image of an extraction signal and an orthogonal transformation image of the watermark embedded image, respectively; amplitude adjustment units 12A and 12B for adjusting amplitude of the two orthogonal transformation images in accordance with a difference between amplitude components of the two orthogonal transformation images; a composite unit 13 for compositing the two orthogonal transformation images whose amplitudes are adjusted; a second orthogonal transforming unit 14 for applying orthogonal transformation to a composite signal and calculating a second orthogonal transformation signal; and an estimate unit 15 for estimating the watermark information on the basis of a peak appearing in the second orthogonal transformation signal.

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