According to the problems which long-focal lens electric two variable or three variable lens in video monitoring system can not realize automatic focusing,this paper puts forward two kinds of control methods of realization of automatic focusing.One is open-loop control,the acquisition method of action time which is the key point is discussed; Another is a closed-loop control,the control process is given,and the commonly used two kinds of image resolution judgment method are analyzed.Finally,an improved algorithm is given.Both control methods have its advantages and disadvantages,in the application,you can use neatly.It can use the two auto-focus control methods which are proposed can be achieved by software,which has low cost and can be widely applied in large long focal length lens video surveillance system.%针对视频监控系统中长焦电动二可变/三可变镜头不能实现自动聚焦的问题,提出了两种实现自动聚焦的控制方法.第一种为开环控制,在此论述了其关键点—动作时间的获取方法；第二种为闭环控制,在此给出了控制流程,并分析了常用的两种图像清晰度判断方法,最后给出了一种改进算法.两种控制方法各有优缺点,可在应用中灵活采用.所提出的两种自动聚焦控制方法可采用软件方式来实现,成本低,能够广泛应用于大范围长焦视频监控系统中.
展开▼
