Robust steganography by modifying sign of DCT coefficients

Abstract

Modern adaptive image steganography with minimizing a distortion function has high performance of undetectability. However, when an image with hidden information is attacked by JPEG compression, its robustness cannot be guaranteed, that remarkably limits its extension from the lab to the real world. In this paper, a novel image steganographic algorithm is proposed that is robust to JPEG compression. First, by using the sign of DCT coefficients, that remains unchangeable before and after JPEG compression, we select the candidate coefficients for resisting JPEG compression. Second, the designed distortion function assigns cost for each candidate DCT coefficient. Finally, relying on both error correction code and Syndrome-Trellis Codes, an encoded message is embedded into the cover image with minimum embedding distortion. Compared with prior arts, extensive experimental results highlight both undetectability and robustness of our proposed algorithm.