Reseach And Implementation Of Auto-focus Control Algorithm Based On FPGA System

Auto-focus technology is the key technology of digital imaging systems. Asit is a key factor that determines the display quality of the imaging systemdirectly,this technique has benn widely used in a variety of imaging devices. Thetraditional focus technology can not meet the digital imaging systemrequirements of cost, applicability and complexity.AF control technique based onthe evaluation function has has greatly improved in cost, practicality and soon.So now it has been widely used.The key methods to study autofocus technology includs image evaluationfunction algorithm and motor search control algorithm. This paper mainly focuseson the search motor control algorithm to study and improve it to improve the AFspeed and accuracy.Considering DSP and ARM systems currently used at highcost of implementation, we design FPGA-based AF system that can effectivelyreduces the cost.Firstly, this paper studies two motor search control algorithm which arebetter than others in practice and compare the effects of two algorithms. Based ona number of evacuation function data in condition of low-cost equipment I do asequence of analysis.The result shows that the effect does not meet myexpectations. Based on this I proposed an improved algorithm which combinesthe advantages of the former two algorithms. By the comparison of a numbersimulation data of experiments in MATLAB it proves that the new algorithm hasgreatly rise the accuracy of the best focus location while the AF speed increasedby some extent.This paper designs the whole AF system plan based on FPGA.Thanks to theapplication of ping-pong storage mechanism of doubled SDRAM and efficientmotor search control algorithm. So the system has good performance of real-timeand accuracy. As a result of low-cost electric lens we make cost ofimplementation lower. This paper accomplishes some module part of the FPGAhardware modules: SDRAM pingpong controller, the DC PWM controller andVGA controller. System hardware designed in Verilog,which is hardwaredescription language,based on QuartusII has pass through the compiler andsimulation. The actual results of AF focus test system is done in the environmentof the surveillance developed by wuhan jiayeheng Co., Ltd.The results prove that the system has good AF focus speed and accuracy.