METHOD FOR IMBEDDING AND DETECTING ELECTRONIC WATERMARK, DEVICE FOR IMBEDDING AND DETECTING ELECTRONIC WATERMARK, AND STORAGE MEDIUM WITH ELECTRONIC WATERMARK IMBEDDING AND DETECTION PROGRAM STORED THEREIN, AND ELECTRONIC WATERMARK SYSTEM AND INTEGRATED CIRCUIT

摘要

PROBLEM TO BE SOLVED: To detect an electronic watermark from a partial image by adding a watermark pattern resulting from applying discrete inverse Fourier transform to a watermark series matrix, after revision to an original image in a form of tiles to generate an imbedded image and to quicken image processing. SOLUTION: An imbed object component designation section 130 uses key information 104 to generate imbed object component position information 131 and gives the information 131 to a component value revision section 140. An imbed series generating section 120 spreads position marker information and an electronic watermark 103 to an imbed series 121 and gives the result to the component value revision section 140. The component value revision section 140 uses the imbed object component position information 131 and the imbed series 121, to set a null matrix to a watermark coefficient matrix 141 as its initial value. The component value revision section 140 revises component values of the watermark coefficient matrix 141 that is a complex matrix set initially to the null matrix, and a discrete inverse Fourier transform section 150 applies discrete inverse Fourier transform to the watermark coefficient matrix 141 to generate a watermark pattern 151. Then a watermark pattern addition section 110 emphasizes the watermark pattern by using a strength parameter 102, to provide an output of an imbedded image 105 that results from adding the watermark pattern to the input original image 101 in a form of tiles.