隐含异位联合编码的密文图像可逆信息隐藏

Objective The technology of reversible data hiding in encrypted images(RDHEI)aims to embed secret informa⁃ tion into encrypted images,ensuring that the secret information and the original image can be extracted and restored with⁃ out loss. This technology is gaining increasing attention from researchers and is widely applied in cloud services to protect users’privacy. Currently,RDHEI can be mainly divided into two categories:the VRAE(vacating room after encryption) algorithm and the RRBE(reserving room before encryption)algorithm,based on the order of image encryption and room operation. The VRAE algorithm vacates space by compressing the pixels of the encrypted image. This compression yields only a limited amount of space due to the high information entropy of the encrypted image. In contrast,the RRBE algorithm primarily compresses the image using pixel correlation before encrypting it. The original image has lower information entropy;thus,more space can be reserved before encryption. This paper proposes a new RDHEI scheme based on bit-plane compression containing opposite bits and leverages the correlation between the encoding information delivery effi⁃ ciency and adjacent pixels to improve the performance of reversible data hiding in encrypted images. Method First,bit-plane rearrangement and pixel prediction methods are adopted to ensure the utilization of the correlation between adjacent pixels. The image owner initially divides the original image into several equally sized blocks and calculates the prediction errors of the original image pixels. Afterward,the eight bit-planes of the processed image are rearranged. In the phase of bit-plane compression,a combined encoding method containing the opposite bit is introduced. Specifically,based on the threshold length,the image bitstream is divided into continuous and discontinuous streams for compression. After com⁃ pressing a continuous bitstream string,the next opposite digit at the end of the string is include;that is,each long com⁃ pressed bitstream adds an opposite digit. According to this rule,the rearranged images are compressed and sequentially placed in each high-level plane with additional information. Encryption and scrambling operations occur at this point. The room in the low-level plane is then vacated,and the information hider embeds the data into the reserved space of the encrypted image. Finally,the image receiver extracts the original image or secret information without loss based on the dif⁃ ferent keys used. Result Experimental comparisons with six advanced methods on six standard test images and two common datasets,namely BOSSBase and BOWS2,are conducted to evaluate the effectiveness of this algorithm. The embedding rate is used to measure algorithm performance,while peak signal-to-noise ratio(PSNR)and structural similarity(SSIM) indicators serve as quantitative evaluation metrics for lossless reversible recovery. Experimental results show that the aver⁃ age embedding rates of the proposed algorithm on the BOSSBase and BOWS2 datasets are 3. 818 3 bpp and 3. 694 3 bpp, respectively,demonstrating superior performance compared to similar algorithms. PSNR and SSIM are constant values equal to +∞ and 1,indicating the reversibility of the algorithm. Conclusion The proposed algorithm uses the image correla⁃ tion of the original image and effectively explores the potential of the encoded and compressed information during the encod⁃ ing and compression processes. This algorithm addresses the issue of compression loss caused by the short and large num⁃ ber of continuous bitstream strings in practical applications,thereby improving compression efficiency and enhancing the embedding rate.