Research On Topic Tracking In News Video Broadcasts

News video topic tracking techniques can be used to scout news reports in every news station, detect the same topic, track the develop of event, present the cause-and-effect generating of event. They can advance the video information value in use and satisfy the demand of some units and individual with a wide application foreground in information security, video library, etal. In this paper, we have studied news video topic tracking techniques and obtained the following three achievements mainly.(1) We have researched keyframe extraction technology and proposed a synthesizing method based upon global statistic. Unlike traditional methods, we obtain a synthesized frame according to the possibilities that pixel values appear at the same position of every frame. Experimental results indicate that this method has sufficiently considered both spacial and temporal information of every frame in the shot and has better shot information representation than conventional methods.(2) We have studied the near duplicate keyframe detection of news video, and a BIC (Bayesian Information Criterion) based method is proposed. Firstly, corner points of the frame are detected and feature vectors are extracted at these points; then whether two frames are near-duplicate or not can be judged by comparing their feature vectors using BIC. Experimental results show that this method, which doesn't need threshold value and machine learning, has better recall and precision than conventional methods.(3) We have researched topic tracking techniques of news video, and proposed a multimodal feature matching fusion method to track topic. In this method, both low-level features and near-duplicate features are used in keyframes similarity detection. We use a linear weighted fusion method for combining the relevance outcome, get story order from frames similarity score, and then extend query corpus and story corpus to accomplish tracking. Experiment results prove that this method has more powerful tracking ability than use global features or local features alone.