Robust watermarking techniques are always used for copyright protection and ownership assertion.Many watermark embedding schemes in transform domain are proposed such as 2-D DFT

2-D DCT and 2-D DWT which are used to transform the image data

and 3-D DCT and 3-D DWT which are used to transform the video data and 3-D image data.In this paper

a gray-level image watermarking scheme based on 3-D separable wavelet transform(SWT) with lifting scheme is presented.A gray-level image is decomposed into a 3-D image sequences by sub-sample of zigzag scan which are transformed using 3-D SWT.Simultaneously it is proved that the distribution of 3-D SWT coefficients follow the generalized Gaussian density function by using the distribution relative entropy theory.To make the compromise between the robustness and the imperceptivity

a new 3-D HVS model is reconstructed and used to adjust the embedding strength.In watermark detection

the optimum detector is used to implement the blind detection.It is shown in our experiments that the scheme is strongly robust against various attacks.