| 摘要 |
PROBLEM TO BE SOLVED: To provide an electronic watermark information detecting method by which imbedded electronic watermark information can surely and quickly be read even when conversion by magnification/reduction is applied to a digital image to the frequency component value of which the electronic watermark information is imbedded. SOLUTION: This invention provides the electronic watermark information detecting method where an image is divided into blocks with a size, a frequency component by each block is obtained, and the electronic watermark information is detected from an image resulting from applying magnification or reduction conversion to the original image a prescribed frequency component by each block of which the electronic watermark information is imbedded. The converted image is received, the converted image is divided into blocks with a prescribed size, processing for detecting the electronic watermark information is applied to the divided image, when no electronic watermark information is detected, to block size is revised, and the detection processing and the block size revision are conducted until the electronic watermark information is detected.
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