| Multiscale geometric transform can represent two-dimensional or higher dimensional singularity, and it can better capture the directional information of the image, which is advantageous to hide watermark information. Moreover, extended discrete shearlet transform has the characteristics of multi-resolution and multiple direction. Relative to other multiscale geometric transformation, extended discrete shearlet can better describe the feature information of the image. In this paper, extend discrete shearlet transform is applied to the digital watermarking technology, and the main work is as follows:(1) A non-blind image watermarking algorithm of SVD and extend discrete Shearlet vertical cone is proposed. In the algorithm, in vertical cone, extend discrete Shearlet transform is performed on image and different directional sub-images can be obtained. Calculate the image entropy and choose the directional sub-image with the maximum entropy as watermark embedding location. In order to improve the robustness of the algorithm, the watermarking information is embedded into low-frequency singular value of the direction sub-image with the maximum entropy. The experimental results show that, under no attack, this algorithm has better imperceptibility. After adding attacks, the algorithm can resist a series of attacks, which means this algorithm has stronger robustness.(2) The watermarking algorithm of SVD and extend discrete Shearlet vertical cone is applied to the blind image watermark. In the process of the blind image watermark embedding, in the same way, the watermark information is embedded into the low frequency singular value of directional sub-image with the maximum entropy to improve the robustness of the algorithm. The algorithm is simulated by MATLAB. The simulation results show that, under no attack, the algorithm can realize the watermark embedding and extraction. At the same time, the algorithm has better imperceptibility. After adding different attacks to the embedded watermark image, the watermark information can still be extracted and this algorithm has stronger robustness. |
