  The popularity of various social platforms has prompted more people to share
their routine photos online. However, undesirable privacy leakages occur due to
such online photo sharing behaviors. Advanced deep neural network (DNN) based
object detectors can easily steal users' personal information exposed in shared
photos. In this paper, we propose a novel adversarial example based
privacy-preserving technique for social images against object detectors based
privacy stealing. Specifically, we develop an Object Disappearance Algorithm to
craft two kinds of adversarial social images. One can hide all objects in the
social images from being detected by an object detector, and the other can make
the customized sensitive objects be incorrectly classified by the object
detector. The Object Disappearance Algorithm constructs perturbation on a clean
social image. After being injected with the perturbation, the social image can
easily fool the object detector, while its visual quality will not be degraded.
We use two metrics, privacy-preserving success rate and privacy leakage rate,
to evaluate the effectiveness of the proposed method. Experimental results show
that, the proposed method can effectively protect the privacy of social images.
The privacy-preserving success rates of the proposed method on MS-COCO and
PASCAL VOC 2007 datasets are high up to 96.1% and 99.3%, respectively, and the
privacy leakage rates on these two datasets are as low as 0.57% and 0.07%,
respectively. In addition, compared with existing image processing methods (low
brightness, noise, blur, mosaic and JPEG compression), the proposed method can
achieve much better performance in privacy protection and image visual quality
maintenance.
