基于FPGA的数字相机自动曝光技术研究

针对传统的自动曝光算法不能满足特殊光照条件的场合,在研究数字相机的工作原理及特点的基础上,实现一种以现场可编程逻辑器件(FPGA)为控制核心的数字相机自动曝光系统,提出了基于图像熵的一种新的自动曝光算法.工作在外触发下的数字相机通过CameraLink接口作为图像数据的输入,利用FPGA的高速并行性完成了数字图像数据的采集、数据流的缓存控制,并且综合分析了基于图像熵的图像分区自动曝光算法的原理和过程,给出了该算法具体的实现方法,最后将得出的曝光参数输出给相机以达到合适的曝光.经实验验证:该算法的曝光效果不但适用于普通光照,而且在特殊光照条件下同样能很好的曝光,不受光照条件的影响,提高了相机系统输出图像的动态范围.

Study on technology of digital camera automatic exposure based on FPGA

Due to the need of the special illumination condition can not be met by the traditional automatic exposure algorithm, it designs a digital camera automatic exposure system using FPGA as the control core in research of the basic work principle and characteristic of digital camera, and presents a new automatic exposure algorithm for image based on entropy. 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, data cache control by high speed parallel characteristics and comprehensively analysis of the principle and process of image partition automatic exposure algorithm based on image entropy. It gives the realization method of the specific algorithm and finally draws to appropriate exposure parameter. Experiments prove: The exposure result of the proposed algorithm is not only suitable for general illumination, but also in the special illumination condition. The system is not affected by light conditions, and even improves the dynamic range of the camera system of the output image.