Abstract:A new algorithm to detect targets is proposed.Firstly,the first frame of video is used as the background frame,then the weighted accumulative image way is used to update the background.The update rate of background image is determined by the adjacent frame difference,the moving target is extracted by background difference algorithm.The entropy of moving target area is calculated,the characteristics of the target is estimated by entropy value. The simulation results show that the algorithm is simple and has good stability,and it can better solve the problem of dynamic background and detect the specific goal.