Dual-JPEG-image reversible data hiding

Because of the widespread popularity of JPEG image compression format, reversible data hiding (RDH) for JPEG images has practical application value with increasing research attention. This paper proposes a dual-image RDH method based on a modification of the discrete cosine transform (DCT) coefficients. Because of the limited embedding capacity, a dual-image strategy is introduced and improved according to the characteristics of JPEG. In our method, all nonzero DCT coefficients are embedded without the additional dis-tortion caused by invalid modifications, and the spatial distortion caused by the modifica-tion of DCT coefficients with different frequencies varies. A dynamic allocation method is proposed to arrange the embedding capacity reasonably to achieve less distortion. The nonzero DCT coefficients can be embedded flexibly with different bits of secret data to sig-nificantly improve the embedding capacity. As far as we know, this is the first work to achieve RDH in JPEG images in a dual-image manner. Furthermore, we also apply the pro-posed method to the reversible authentication of JPEG images. Experimental results demonstrate the efficacy of the proposed method with high embedding capacity and sat-isfactory visual quality while suppressing file size expansion. (c) 2021 Elsevier Inc. All rights reserved.