High-capacity reversible data hiding in encrypted images based on adaptive block coding selection

Recently, data hiding techniques have flourished and addressed various challenges. However, reversible data hiding for encrypted images (RDHEI) using vacating room after encryption (VRAE) framework often falls short in terms of data embedding performance. To address this issue, this paper proposes a novel and high-capacity data hiding method based on adaptive block coding selection. Specifically, iterative encryption and block permutation are applied during image encryption to maintain high pixel correlation within blocks. For each block in the encrypted image, both entropy coding and zero-valued high bit-planes compression coding are pre-applied, then the coding method that vacates the most space is selected, leveraging the strengths of both coding techniques to maximize the effective embeddable room of each encrypted block. This adaptive block coding selection mechanism is suitable for images with varying characteristics. Extensive experiments demonstrate that the proposed VRAE-based method outperforms some state-of-the-art RDHEI methods in data embedding capacity. The average embedding rates (ERs) of the proposed method for three publicly-used datasets including BOSSbase, BOWS-2 and UCID, are 4.041 bpp, 3.929 bpp, and 3.181 bpp, respectively.