Privacy-Preserving Recoverable Photo Sharing in Mobile Social Network
Huaibo Sun, Hong Luo, Yan Sun · 2016
It is common to take photos and share them by smartphone in mobile social network at present, but the sharer may need to mask partial areas of the photo to avoid leaking the privacy. Reversible image mosaic can mask the privacy very well. However, there is little discussion on how to effectively control and safely store the mosaic information for recovering. In this paper, we first propose a prediction algorithm of reversible image mosaic size (PARIMoS), which can calculate the maximum number of mosaic blocks according to the image quality of non-mosaic area and the recovery quality of mosaic required by user. And then, we propose an efficient and reliable generating algorithm of reversible image mosaic (GAoRIM). In GAoRIM, we compress the secret information of the mosaic area with twice-run-length-encoding and then store the compressed result in special non-mosaic areas of image separately. Therefore, it can ensure reliable recovery even the image is partly stained, and hardly change the roughness of non-mosaic area. The experiment results show that the biggest change of average roughness in the non-mosaic area is less than 0:5%. Comparing with the similar algorithms, on average, the amount of data protected by GAoRIM is at least 8:70% higher than theirs while the peak signal noise ratio (PSNR) of stego image without mosaic is similar to theirs.