High Capacity Reversible Data Hiding in Encrypted Images Based on Pixel Value Preprocessing and Block Classification

Reversible data hiding in encrypted images (RDHEI) can simultaneously achieve secure transmission of images and secret storage of embedded additional data, which can be used for cloud storage and privacy protection. In this paper, an RDHEI scheme based on pixel value preprocessing and block classification (PVPBC-RDHEI) is proposed. The content owner first preprocesses the pixel values of the original image and then encrypts the image by combining bitwise exclusive-or operation and block permutation, so that the correlation between neighboring pixels in the encrypted image block is preserved. Upon receiving the encrypted image, the data hider classifies all blocks into six types based on the number of continuously consistent value bit planes counted from top-down in the pixel block, and generates corresponding indicators for six block types using Huffman coding. Therefore, each pixel block in the image can vacate room for data embedding. The receiver can separately extract the additional data or recover the original image according to the different keys. The experimental results show that the embedding rate of the proposed scheme is significantly superior to the state-of-the-art schemes, and the security and reversibility are guaranteed.