基于数字全息的Contourlet-SVD域水印算法

The watermarking algorithm based on digital holography and Contourlet-SVD domain

将数字全息技术和Contourlet-SVD域相结合,提出一种基于Contourlet-SVD域数字全息的水印算法。首先共轭对称扩展傅立叶数字全息方法用于生成相应的全息水印图像,将载体图像进行2级Contourlet变换,将产生的与原载体图像大小相同的低频子带进行SVD分解,确定嵌入强度后将水印信息叠加到奇异值矩阵中,实现水印的嵌入。通过仿真实验发现,该算法在保证水印信息量的前提下,满足了水印信息的隐蔽性,嵌入水印图像的峰值信燥比(PSNR)值达到30 dB以上,提取出的水印图像和原始水印图像的相似性(NC值)达到了0.9858,同时该算法对椒盐、高斯噪声和中通滤波攻击的鲁棒性较强,提取出的水印图像和原始水印图像的相似性(NC值)均达到0.90以上,提取出的水印图像可以清晰识别。提出的算法可以有效的保存水印信息,并且对常规攻击具有良好的抵抗能力。

Combining digital holography with Contourlet-SVD domain,a watermarking algorithm based on Contourlet-SVD domain and digital holography is proposed.First,the conjugate symmetric extended Fourier digital holography method is used to generate the corresponding holographic watermark image.A 2-level Contourlet transform is performed on the carrier image,and the generated low-frequency sub-bands of the same size as the original carrier image are subjected to SVD decomposition.Then,after determining the embedding strength,the watermark information is superimposed into the singular value matrix to realize the embedding of the watermark.Through the simulation experiments,it is found that the algorithm satisfies the concealment of watermark information under the premise of ensuring the amount of watermark information.Peak signal-to-noise ratio of embedded watermark images(PSNR)reaches 30 dB or more,and similarity between the extracted watermark image and the original watermark image(NC value)reaches 0.9858.At the same time,the algorithm is robust to salt and pepper,Gaussian noise and medium pass filtering attacks.Similarity between the extracted watermark image and the original watermark image(NC values)are all above 0.90,and the extracted watermark images can be clearly identified.The proposed algorithm can effectively preserve the watermark information and has good resistance to conventional attacks.