Improved Roberts focusing evaluation method for an autofocusing system

In this paper, a new focusing evaluation method based on local 2/8 center windows is proposed for an autofocusing system. We have proposed an evaluation function which improved the Roberts function with eight-neighborhood or four-neighborhood. The approximate optimal criteria window is selected by a 2/8 rule. Comparative experiments implemented with other methods have shown that the 2/8 rule method not only can find the approximate optimal evaluation window quickly, but also has better generality. This evaluation function of improved Roberts’ function has higher sensitivity and better real-time performance.