Auto-focusing system based on DSP

The focus evaluation functions on the basis of spatial domain are analyzed. Then, Tenengrad function based on Sobel operator is chosen as the focus evaluation function. Tenengrad function is improved to overcome the great computation cost and a x/y Tenengrad function which can be real-timely implemented in the Digital Signal Processing (DSP) platform is put forward. Experimental results indicate that with almost the same focusing precision, the focusing computation time for per image of 768 × 576 is within 25 ms, which is one thirty-fifth of that of the classic Tenengrad function. By finishing the video driver and UART driver in the TMS320DM642 platform, an auto-focusing system comprising x/y Tenengrad function and global searching algorithm is set up successfully.