A RST-invariant Robust DWT-HMM Watermarking AlgorithmIncorporating Zernike Moment and Template
结合Zernike矩和模板具有RST不变性的DWT-HMM鲁棒水印算法

One of the key issues for robust watermarking is to resist geometrical attacks.A matching strategy from coarse to fine scale to achieve the geometrical synchronization incorporating Zernike moments and the template in wavelet domain is proposed.At the coarse stage,the rotation and scaling parameters are estimated with the Zernike moments of the translation-normalized image,while the translation parameters are estimated with the centroid's increments between the original image and the image that are corrected for rotation and scaling.At the fine stage,the accurate values of rotation,scaling,and translation(RST)are obtained by matching the template around the roughly estimated RST values,which hence reduces the searching spaces to some extent.Finally,the attacked image is corrected with the accurate RST values.A watermarking scheme based on the vector Hidden Markov Model in wavelet domain(DWT-HMM)is also adopted.Good robustness is observed against StirMark attacks and their joint attacks.