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    基于像素预测和块标记的图像密文可逆信息隐藏

    Reversible Data Hiding in Encrypted Images Based on Pixel Prediction and Block Labeling

    • 摘要: 图像密文可逆信息隐藏是一种在加密图像上嵌入附加的信息,并能无损地提取信息和恢复原始图像的技术.由于该技术不仅能有效地实现信息传递,还能保障传输载体的安全性,所以随着云计算的发展和对隐私保护的需求的日益增长,近年来图像密文可逆信息隐藏逐渐得到广泛的关注.基于像素预测和分块标记的图像密文可逆信息隐藏算法,重点研究如何在保障安全性的同时,实现高嵌入容量和完全可逆性.在预处理阶段,采用中值预测的方法计算得到图像的预测误差.不同于之前的算法,该算法使用最高有效位表示预测误差的符号位,其余位平面表示数值位后得到预测误差位平面,并将预测误差位平面分块后自适应地标记.所得到的标记序列具有稀疏特征,可以使用算术编码有效压缩.在加密阶段,使用密钥生成伪随机矩阵,对原始图像的像素执行异或操作.在信息隐藏阶段,对于每种分块使用不同方法嵌入附加信息.最后根据相应密钥即可无损地提取信息并恢复原始图像.实验结果表明,提出算法的最终结果相较于此前的同类算法而言,在保证安全性和可逆性的同时,嵌入容量得到明显提升.

       

      Abstract: Reversible data hiding in encrypted images (RDHEI) is an effective technology that can embed additional data after image encryption, extract data error-free and recover images losslessly. It can not only achieve information transmission, but also ensure the security of the transmission carrier. Therefore, with the development of cloud computing and the growing demand for privacy protection, RDHEI has been widely concerned in recent years. In this paper, a RDHEI algorithm based on pixel prediction and block labeling is proposed. The proposed algorithm focuses on how to achieve high embedding capacity and complete reversibility while ensuring security. In the preprocessing step, the median edge predictor is used to calculate the prediction error. Different from the previous algorithms, the proposed algorithm uses the most significant bit to represent the sign of the prediction errors, and the rest of bit planes represent the absolute values of the prediction errors. The prediction error bit planes are divided into several non-overlapping blocks and these blocks are labeled adaptively. The label map with sparse feature can be compressed effectively via arithmetic coding. In the encryption step, the encryption key is used to generate a pseudo-random matrix to encrypt the original image. In the data hiding step, different methods are used to embed additional data for different types of blocks. Finally, according to the corresponding key, the additional data can be extracted error-free and the original image can be recovered losslessly. Experimental results show that, the proposed algorithm can not only ensure the security and reversibility, but also improve the embedding capacity significantly compared with the state-of-art RDHEI algorithms.

       

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