Reversible data hiding in encrypted image using pixel prediction and room reservation

Abstract

Reversible Data Hiding in Encrypted Images (RDHEI) not only enables complete restoration of the original image but also ensures the security of the stego image. Wang et al. proposed a block prediction method to preserve space in 2022. This paper improves upon Wang et al.’s approach by employing inter-pixel group coding and compression techniques to reserve more space for data hiding. The proposed method first generates a prediction image and divides it into non-overlapping groups. Based on the range of prediction errors, Huffman coding is used to label each group type. Groups with smaller prediction error ranges require fewer bits for representation, resulting in increased space for data hiding. Subsequently, the image is encrypted using a secret key, and the encrypted secret message is embedded into the reserved space within the encrypted image. In the experiments, various group sizes were tested for both special and regular groups. The results show that incorporating special group processing, even with the need to record identifiers L and S, can still yield more space overall while the combined size of L and S is smaller than the additional space generated. Furthermore, comparisons with related methods indicate that the proposed approach achieves superior performance.