中文摘要：

为了提高密文图像上的可逆数据隐藏方法的性能,在加密前处理图像以获得数据嵌入空间。首先,分析了在解压缩分块上进行可逆嵌入的可行性;其次,计算了成功恢复解压缩分块的理论概率;最后,提出了基于解压缩分块的密文图像可逆数据隐藏算法,主要过程包括预处理、加密、数据嵌入、数据提取与图像恢复。从图像恢复错误率、嵌入容量和PSNR这3个方面与3种已有方法进行对比,表明所提方法实现了数据提取和图像解密在操作上的完全分离,且图像恢复错误率更低,嵌入容量更大,PSNR更高。

英文摘要：

To improve the performance of RDH（reversible data hiding） method in encrypted images, the embedding room was reserved before encryption and realizes the real separation of the data extraction from image decryption in operation. First, the feasibility of RDH in JPEG decompressed image blocks was researched. Then the theoretical probability of successful recovery of decompressed image blocks was calculated. Finally, a method of RDH in encrypted images was proposed and the main steps of the method include pretreatment, encryption, data embedding, data extraction and image recovery. The performance of the proposed method was compared with three existing RDH methods in encrypted images. The results demonstrate the proposed method has less error in image recovery, and for given embedding rates, the PSNR of decrypted image containing the embedded data are significantly improved.