| 摘要 |
PROBLEM TO BE SOLVED: To make the falsification of an image having digital contents detectable even when noncompression, reversible compression, or non-reversible compression is applied to the image by burying digital watermarking in the image. SOLUTION: After an input cryptographic key is preserved (S1) and image information is preserved (S2), the image information is divided into blocks composed of n×m pixels so that horizontally and vertically adjoining divided blocks may partially overlap each other (S3) and, when the division is not completed ('No' in S4), 'Hash NO' storing hash values is initialized (S5). Then the continuously running length (changing position) of pixel values is found by comparing the pixel values in the blocks with a threshold and, when the processing of all pixels is not completed ('No' in S6), a hash value is found and stored in 'Hash NO' (S7). When the changing position is in a changeable area ('Yes' in S8) which is not subjected to thinning ('No' in S10), the parity of 'Hash NO' is matched to that of the pixel value at the changing position (S11). The picture information is recorded by repeating the above- mentioned processing and burying digital watermarking (S13). The falsification of the image information is detected from the reproducibility of the digital watermarking. COPYRIGHT: (C)2003,JPO |
