Novel Auto-Focusing Method

In this paper, an advanced auto-focusing method is proposed to improve the efficiency of the traditional auto-focusing method based on criterion function with the same accuracy. Firstly, a depth from defocus auto-focusing method based on autocorrelation of differential image is used to give a rough estimate of the right focus position with only two or three defocused images. Then traditional method based on criterion function is used to find accurate focus position in this rough field with fixed step-length mountain climbing servo (MCS). The experimental results demonstrate that this novel method not only maintains the accuracy, but also has some advantages of rapid reaction and good performance for any objects.