An efficient reversible data hiding algorithm using two steganographic images

• A novel dual-image reversible data hiding algorithm is proposed.
• Three consecutive stages that exploit the similarity between the two images to embed data are used.
• Significant increase in the embedding capacity with excellent stego image quality is achieved.

Reversible data hiding (RDH) algorithms are concerned with concealing data within images such that the original image can be fully recovered upon the extraction of hidden data. A substantial interest has grown recently in RDH algorithms that are based on using dual images in order to increase the embedding capacity. In this paper, we propose a RDH algorithm that is based on this concept. Effectively, embedding and extraction of data in the proposed algorithm is performed in three successive phases. In the first phase, four simple rules are used to embed about one bit in each pixel in the two images. On the other hand, the other two phases employ the concept of prediction for embedding secret data bits but without using any complex predictors. Specifically, these phases use one image as the prediction of the other image. Performance evaluation of the proposed algorithm showed its ability to embed around 1.23 bits per pixel with stego image quality above 48 dB. Moreover, the proposed algorithm is of low computational complexity and requires no communication of overhead information.