一种应用于CMOS图像传感器的快速自动曝光控制方法  

A Fast Automatic Exposure Control Method for CMOS Image Sensor

作　　者：戈志伟[1] 姚素英[1] 徐江涛[1] 宿晓慧[1] 

机构地区：[1]天津大学电子信息工程学院,天津300072

出　　处：《天津大学学报》2010年第10期854-859,共6页Journal of Tianjin University(Science and Technology)

基　　金：国家自然科学基金资助项目(60806010);教育部高等学校博士点基金资助项目(200800561111)

摘　　要：针对应用于CMOS图像传感器的传统固定步长自动曝光方法曝光过程缓慢的缺点,设计了一种快速自动曝光控制方法.在相同光照强度下,CMOS图像传感器的曝光强度值与增益值和曝光时间的乘积的比值是一个常量值,基于这一感光特性,根据当前的曝光时间、增益值和图像强度统计值判断出当前的光照强度,基于光强范围查找表,得到最优曝光时间,从而实现快速自动曝光调节.经过MATLAB算法评估,这种曝光方法在暗光情况下正确曝光平均帧数为3.6帧,而传统曝光方法需12.6帧;强光情况下正确曝光平均帧数为3.6帧,而传统曝光方法需要8.8帧.经过FPGA实际验证,这种方法能够很好地应用于CMOS图像传感器,在保证图像正确曝光的情况下实现快速调节曝光时间和增益值.A fast automatic exposure control method against the slow process of the conventional fixed-step automatic exposure control method for CMOS image sensor was proposed. The ratio of the output signals after being exposed to the product of gain value and exposure time is a constant under the same illumination. According to this characteristic, the luminous intensity was obtained by using the current exposure time, gain value and brightness of the object. After the optimal exposure time was obtained by using the light look-up table, fast automatic exposure control was thus realized. After the proposed algorithm using MATLAB is assessed, the result shows that the average frame number achieving the correct exposure is 3.6 frames under conditions of dark light, but for the conventional method the number is 12.6 flames. Under conditions of bright light, it needs 3.6 frames to achieve the correct exposure, but the conventional method needs 8.8 frames. It is verified on FPGA board that the proposed method can be applied to CMOS image sensor well. As it turns out, this algorithm can achieve the goal of quick adjustment of exposure time and gain value on the premise of ensuring correct exposure.

关 键 词：CMOS图像传感器 快速自动曝光控制 曝光时间 增益值 

分 类 号：TN4[电子电信—微电子学与固体电子学]