Parametrization construction of two-dimensional wavelet filters

In this paper, a transformation that we refer to as shift unitary transform (SUT) of conjugate quadrature filter (CQF) is proposed. In terms of this transformation, we present a parametrization method for constructing two-dimensional orthogonal wavelet filters. It is proved that tensor-product wavelet filters are only special cases of this method. Therefore, more ways are provided to randomly generate perfect reconstruction filters. Nonseparable wavelet filters are derived by this method, and applied to a blind watermarking scheme. Experimental results show that watermarking scheme based on these filters is more resistant to sharpening than scheme based on tensor-product wavelet filters.