Robust Human Face Hiding Ensuring Privacy

Nowadays, video surveillance of people must ensure privacy. In this paper, we propose a seamless solution to that problem by masking faces in video sequences, which keeps people anonymous. The system consists of two modules. First, an analysis module identifies and follows regions of interest (ROI's) where faces are detected. Second, the JPEG 2000 encoding module compresses the frames keeping the ROI’s in a separate data layer, so that the correct rendering of human faces can be restricted. The analysis module combines two complementary methods: face detection, to locate faces in the image, and tracking, to follow them seamlessly along the time. The fusion of these two methods increases robustness: once a face has already been detected in a frame, tracking may locate it in the consecutive frames, even when a face detection algorithm would not. In addition, detection of faces prevents tracking from loosing its targets. The encoding module downshifts the JPEG 2000 data corresponding to the identified ROI's to the lowest quality layer of the codestream. When the transmission bandwidth is limited, the human faces will then be decoded with a lower visual quality, up to invisibility when required. The proposed solution has been tested on different types of sequences. The results are presented in the paper.