Reversible Data Hiding in Encrypted Images Using Four-Color Approach

Reversible data hiding in encrypted images (RDHEI) has become a hot topic, and a lot of methods are proposed to optimize this technology. However, these methods do not make full use of image spatial correlation, which may cause their outcomes to be flawed. In this paper, we propose an advanced scheme, the main contributions of which include two points. First, we introduce the four-color theorem approach to the image processing field for the first time. Second, we extend the four-color theorem to facilitate RDHEI. Experiments show that the embedding rate of the proposed scheme can outperform other RDHEI algorithms, and the PSNR value of the recovered image can be infinite.