High-Capacity Reversible Data Hiding in Encrypted Images using Adaptive Encoding.

With the popularization of digital information technology, the reversible data hiding in encrypted images (RDHEI) has gradually become the research hotspot of privacy protection in cloud storage. As a technology that can embed additional information in the encrypted domain, extract the embedded information correctly and recover the original image losslessly, RDHEI has received a lot of attention from researchers. To embed sufficient additional information in the encrypted image, a high-capacity RDHEI method using adaptive encoding is proposed in this paper. Firstly, the occurrence frequency of different prediction errors of the original image is calculated and the corresponding adaptive Huffman coding is generated. Then, the original image is encrypted and the encrypted pixels are marked with different Huffman codewords according to the prediction errors. Finally, additional information is embedded in the reserved room of marked pixels by bit substitution. Experimental results prove that the proposed method outperforms the state-of-the-art methods in embedding rate and can extract the embedded information correctly and recover the image losslessly.