针对传统自动曝光算法难以兼顾实时性和平滑性的缺点，设计了一种结合直接计算法和可变步长调节法的综合性算法，研究了算法原理，给出了算法流程。该算法可以通过改变步长参数，自由设定将图像亮度调节到目标亮度的时间，使其能够适用于各种不同的应用场合。在基于FPGA的CMOS图像采集平台上完成了算法实现，实验结果证明采用该算法可以使图像亮度快速平稳地接近理想亮度，成像效果很好。

A comprehensive algorithm that combines direct calculation method and variable step adjustment method, aiming at the disadvantage of traditional autoexposure algorithm that can not realize instantaneity and smoothness simultaneously, was proposed in this paper. The principles of the algorithm were studied and the design process was provided. The time for adjusting the image brightness to the target value can be set unconditionally by modifying the step size parameter, thus it is suitable for various applications. The algorithm is implemented on the CMOS image acquisition platform based on FPGA and the test results prove that the camera using the algorithm can obtain video images with an excellent quality.