| 摘要 |
PROBLEM TO BE SOLVED: To provide a robust electronic watermark inserting apparatus and a robust electronic watermark detecting apparatus. SOLUTION: The inserting apparatus produces a magnification reduction detecting pattern, a rotary angle detecting pattern, and a data pattern set to a position combined with inserted data among object positions, applies inverse Fourier transform to all the patterns, and adds an image obtained by the conversion to an original image. The detecting apparatus classifies the image into blocks, obtains the amplitude of each frequency component of each block by applying Fourier transform to data of each block, sums the amplitudes of each frequency component between the blocks to obtain a total amplitude of each frequency, detects a magnification / reduction rate by using the magnification reduction detecting pattern, and detects the data on the basis of the combination of a prescribed number of total amplitude positions denoting a relatively greater value among the total sum amplitudes at the object positions on the basis of the total sum amplitude wherein the magnification reduction factor and the rotary angle are corrected. COPYRIGHT: (C)2004,JPO
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