基于预测误差自适应编码的图像加密可逆数据隐藏

Reversible Data Hiding of Image Encryption Based on Prediction Error Adaptive Coding

针对现有算法中加密图像存在安全隐患,及选用编码不佳导致图像压缩率较低的问题,提出了一种基于预测误差自适应编码的图像加密可逆数据隐藏算法.图像加密阶段,设计了一种基于误差维持的图像加密算法,首先对3×3的图像块做块间置乱和像素调制加密,然后根据图像块中心像素值将非中心像素分组置乱.数据嵌入阶段,根据图像自身预测误差分布自适应编码,使用编码表对像素进行标记分类后,将编码表与附加数据共同隐藏在加密图像中生成携密加密图像.实验结果表明:加密阶段分组置乱操作,使原始图像与加密图像中特征值差异块数增多,难以确定加密前后图像中各图像块间的对应关系,提高了加密图像的安全性,且图像整体的预测误差分布保持不变;相较于现有算法,平均嵌入率提高0.49bpp以上,且能无损提取附加数据、恢复原始图像.

For the security problem of existing schemes in the image encryption,and the problem of low compression due to poor coding,this paper proposes a reversible data hiding algorithm of image encryption based on prediction error adaptive coding.In the image encryption stage,an image encryption algorithm based on error maintenance is designed.First,block scrambling and pixel modulation encryption are performed on 3×3 image blocks,and then non-center pixels are grouped and scrambled according to the central pixel value of the image block.In the data embedding stage,adaptive coding is based on the prediction error distribution of the image,after marking and classifying the pixels with the coding table,and the coding table and additional data are hidden together in the encrypted image to generate a marked encrypted image.The experimental results show that group scrambling operation in the encryption phase increases the number of eigenvalue difference blocks between the original image and the encrypted image,makes it difficult to determine the correspondence between the image blocks in the image before and after encryption,improves the security of the encrypted image,and keeps the overall prediction error distribution of the image.Compared with state-of-the-art algorithms,the average embedding rate can be improved by more than 0.49bpp,the additional data can be extracted losslessly and the original image can be restored.