Abstract: According to the principles,characteristics and the advantages of the application of DWT and SVD theory in watermarking field,this paper presents a singular value decomposition of block-based watermarking technology in wavelet domain.The decomposition advantages of wavelet and singular value are made full use of.In accordance with the idea of carved blocks in JPEG program,wavelet transformation is firstly made to the host image.Then singular value decomposition is done to the low frequency parameters.The largest singular value of each block is selected to a new matrix to be embedded into water-mark information.Moreover,multiple extraction methods is presented to cope with various attacks.Experimental results show that the algorithm is robust enough to some  image degradation process.

Key words: blind-watermark, singular value decomposition (SVD), wavelet domain, robustness