适用于大动态范围场景的自动曝光控制算法

针对数码成像系统在大动态范围场景下存在的对主体曝光不足或曝光过度的问题,本文提出了一种新的自动曝光控制算法.该方法将图像窗口分割成M×N个矩形块,利用大动态范围场景中主体与背景之间所具有的较大的对比度,采用一个主动搜索的过程将主体鉴别出来,随后根据主体与背景之间的亮度关系对光照条件进行判断,并且在计算图像整体亮度水平时赋予主体与背景相应的权重从而更多地反映出主体的信息.实验结果表明,算法对所有的评估场景都做出了正确的光照条件判断,其在大动态范围场景下拍摄的预览帧数和曝光误差分别小于8.8帧和6.56%.

Auto-exposure Algorithm for Scenes with Large Dynamic Range

The proposed algorithm for digital imaging system ensures correct exposure to the main object of scenes with large dynamic range. The image window was divided into M×N tiles. Using the contrast between the main object and the background of large dynamic scenes,the algorithm identified the main object through a certain search process,detected the lighting condition based on the search result,and then assigned different weights to the main object and the background so that the overall brightness level was made to carry more information of the main object. The experiment results show that the lighting conditions of all the scenes for evaluation are correctly detected. For the high dynamic range lighting conditions,the number of preview frames and the exposure error are less than 8.8 frames and 6.56% respectively.