Real-time camera tampering detection using two-stage scene matching

We propose a tampering detection method using two-stage scene matching for real application with high efficiency and low false alarm rate. In the first stage, we use the intensity of edges as the main cue to detect the camera tampering events. Instead of using the entire edge points of the images, we sample the most significant edge points to represent the scene. Analyzing the edge variation with only the sample points, we discover that the events of camera tampering can be detected with low computation cost. Whenever the first stage detects the tampering event, the second stage is triggered to reduce false alarms. In the second stage, we propose an illumination change detector which can check the consistency of the scene structure using cell-based matching method. The experimental results demonstrate that our system can detect the camera tampering precisely and minimize false alarm even when the illumination changes dramatically or large crowds passing through the scene.