Research On Auto-focusing And Auto-dimming In Embedded Platform Of Optical Imaging System

Auto-focusing and auto-dimming are important functions of the imaging system and important guarantees of imaging quality.For real-time changing scene and illumination conditions,the system can accurately and steadily complete the auto-focusing and auto-dimming control,which is of great significance to the follow-up image processing of the imaging system.According to the actual situation,a miniaturized embedded optical focusing imaging system and a miniaturized embedded dimming imaging system are constructed in this paper,and the methods of auto-focusing and auto-dimming based on image processing are studied.The main research work completed in this paper is summaried as follows:1.Understanding the development status of auto-focusing and auto-dimming research at home and abroad and the basic principle of auto-focusing and auto-dimming of optical imaging system.Combining with the requirement of project scene,the selection of zoom lens and CCD imaging module is completed,and the embedded auto-focusing platform based on ARM architecture is constructed.The type of CMOS imaging sensor is selected and an embedded automatic dimming platform based on FPGA architecture is built.2.Research on auto-focusing of embedded optical imaging system: Based on the motor drive design and software control scheme design of the optical imaging system,the method of focusing window selection based on image entropy and the method of evaluating area selection based on the maximum gray difference of row pixels are proposed.The results of outdoor experiments show that the method can obtain a good focusing evaluation curve,improve the stability of the system and reduce the focusing evaluation time.3.Research on auto-dimming of embedded optical imaging system: A two-stage adaptive dimming method based on embedded platform is proposed.Firstly,the adaptive adjustment is completed based on the luminance histogram,then the appropriate light measuring area is selected according to the adjustment condition,and finally the search adjustment based on image entropy is realized.The experimental results show that the method has good environmental adaptability.