An Image Zero-watermarking Algorithm in DT-CWT Domain
一种DT-CWT域内的图像零水印算法

To achieve the copyright protection of digital image,we present a novel zero-watermarking algorithm based on DT-CWT(dual-tree complex wavelet transform).The algorithm doesn't modify any information of the image,therefore it possesses both the invisibility and robustness,while it can resolve the loss of energy of conventional watermarking algorithms based on redundant transform.Exploiting the idea of real wavelet zerotree structure,we choose the vital-coefficient-trees from the transformed image,then by using PCA(principal component analysis),extract the first principal components,quantize and encode them to construct the zero-watermark signal,which is registered to the center of authentication and is used to identify user's copyright later.Experiments show,that the robustness of the algorithm is very good,and it can resist various attacks such as filtering,noising,lossy compression,etc..