Reversible Data Hiding in Jpeg Images for Privacy Protection

Recently, how to protect privacy in JPEG images has become an important issue in social networks. Besides encryption, reversible visual transformation has been studied for content and privacy protection. In this paper, an improved algorithm is proposed to conceal privacy information in JPEG images. By adopting face detection, the regions to be protected can be identified so that the DC and some AC coefficients in them are modified. The changes that have been made are reversibly saved in the other AC coefficients, and the block selection information is hidden into the whole image also by reversible data hiding. As a secret key is employed to control the process of transformation, the protected content can hardly be obtained without knowing the key. We conduct the proposed algorithm on a set of test images, and compare the performance with several existing algorithms in terms of information leakage, file size increment, and image quality. The experimental results show that improved image quality and less information leakage can be achieved with the proposed reversible transformation algorithm.