Abstract: This paper implements a student position detection and face image acquisition system based on classroom monitoring video. The system consists of a fixed focus panoramic camera and a PTZ camera. At first, the fixed camera obtains a panoramic image of the actual classroom environment. An abnormal light elimination algorithm based on the frame difference is proposed to realize the abnormal light and empty classroom detection and background image storage. The face detection is realized by HR network structure, which obtains a set of face detection boxes. As the lack of face information caused by the change of posture, occlusion and low resolution, this paper proposes a weighted moving target detection algorithm based on human head and shoulder feature to get target detection boxes, improving the position detection rate of students without face information. Aiming at the large amount of redundancy of multiple detection frames, this paper proposes multiple detection frame weighted fusion algorithms to effectively reduce the detection boxes. After the repetition of the test frame, the set of student character test frame is obtained. Then, the 〖JP2〗position information contained by the position detection is transmitted to the PTZ camera control subsystem, so that the PTZ focuses on the target students one by one, capturing a clear student face image, and providing a high quality image for face recognition.

Key words: face detection, moving object detection, frame difference, PTZ control