Study On Technology Of Digital Camera Automatic Exposure Based On FPGA

With the development of modern image technology, especially the constant improvement of CCD camera, CCD camera has been a important role in the areas of military,industrial. And it also be required to have high quality of the image. If the carema, which have large dynamic range and good quality, can't ensure the quality of the image, then the automatic exposure technology is undoubtedly one of the best ways and means for CCD camera to improve the quality of image. However, the current automatic exposure mode of digital camera is a generalization, is not suitable for some special requirements. So it is necessary to study automatic exposure technology of digital camera.In view of the traditional automatic exposure algorithm can't satisfy the special light conditions, the paper designs a kind of digital camera automatic exposure system using FPGA as control core, based on the study of the working principle and characteristics of digital camera. The digital camera which works in the external trigger mode transmits image data through Camera-Link interface. FPGA completes high frame rate digital image acquisition and data cache control by high speed parallel characteristics. The paper comprehensively analyze the principle and process of image partition automatic exposure based on image entropy. It also gives the method of using FPGA to realize automatic exposure, and finally draws to appropriate exposure parameter. At last, the carema adjust exposure time using exposure parameter provided by FPGA. Experiments prove that the exposure technology of the system is not only suitable for general illumination, but also in the special illumination condition. So the system is not affected by light conditions and meet the requirement of the subject.