| 摘要 |
The present invention discloses an asymmetric watermarking technology, which is particularly resistant to projection attack. The asymmetric watermark embedding technology of this invention comprises the following steps: Analyze an original image phi<SUB>o </SUB>to obtain its watermarking space W. Divide said watermarking space W to obtain two orthogonal subspaces g and h. Select an embedding key G, which is a matrix and which columns form bases of subspace g. Calculate a matrix H, H<SUP>T</SUP>G=0. Columns of matrix H form bases of subspace h. Calculate detecting key D: <?in-line-formulae description="In-line Formulae" end="lead"?>D=G<SUP>T</SUP>+BH<SUP>T</SUP>; <?in-line-formulae description="In-line Formulae" end="tail"?> wherein B is a matrix. Obtain a watermark w and embed said watermark w into said original image phi<SUB>o </SUB>to obtain a watermarked image phi<SUB>w</SUB>, as follows: <?in-line-formulae description="In-line Formulae" end="lead"?>phi<SUB>w</SUB>=phi<SUB>o</SUB>+Gw <?in-line-formulae description="In-line Formulae" end="tail"?> wherein D phi<SUB>o</SUB>=m<SUB>o </SUB>is not a 0 vector.
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