直方图移位安全可逆图像水印算法的研究

Research on histogram shift safe reversible image watermarking algorithm

针对一些在数字版权保护和多媒体信息安全领域中,需要对嵌入的水印信息进行加密来确保水印信息的机密性,提出直方图移位安全可逆的图像水印算法。对载体图像的最大像素值和最小像素值分别进行减一加一的操作,并且对该像素值进行标记,图像预处理的方法,解决了嵌入水印信息时像素值修改产生的溢出问题。利用祖冲之序列密码算法(ZUC算法)对水印信息进行加密。在水印嵌入阶段,计算每个半平面像素的四邻域、八邻域的预测差值,来构建二维直方图,嵌入加密的水印。实验结果表明,算法能够无损地恢复原始载体图像,加密水印信息能够正确解密,含加密水印图像的峰值信噪比均达到50 dB以上;该方案具有良好的加解密效果,水印图像具有很好的质量和水印隐蔽性,算法具有可逆性,并且解决了像素溢出的问题。

In the field of digital copyright protection and multimedia information security,the embedded watermark information needs to be encrypted to ensure the confidentiality of the watermark information,so a safe and reversible image watermarking algorithm for histogram shift is proposed.The maximum and minimum pixel values of the carrier image are subtracted one and added one respectively,and the pixel value is marked.The carrier image is preprocessed to solve the problem of overflow caused by pixel value modification when embedding watermark information.The watermark information is encrypted using ZUC sequence cipher.In the stage of watermark embedding,the predicted difference of four fields and eight fields of each half-plane pixel is calculated to construct a two-dimensional histogram,and then the encrypted watermark is embedded.Experimental results show that the algorithm can restore the original carrier image lossless,the encrypted watermark information can be decrypted correctly,and the peak signal-to-noise ration value of the encrypted watermark image reaches more than 50 dB.The experimental results further illustrate that the scheme has good encryption and decryption effects,the watermark image has good quality and watermark concealment,the algorithm is reversible,and solves the problem of pixel overflow.