Dsp-based Autofocus Technology

In this paper we discussed an auto-focus system which is based on DSP and applied in digital video presenter. The video signal from digital CMOS image sensor is calculated in DSP to get a focus value,then the proper focusing position is found using optimized hill-climbing searching arithmetic,the step motor will drive the lens to this position to get a well focused image. This system is also suitable to other devices that need auto-focus technique such as microscope,vidicon and digital camera etc.The hardware and software in this auto-focus system is introduced particularly . The hardware includes digital image sensor,USB interface,DSP system,zoom lens and it's driving system . The software in this system is basically made up of USB communication software,video signal sampling and processing,optimized HCS(hill-climbing searching) arithmetic and step motor driving software.