An automatic exposure algorithm based on information entropy

According to the digital imaging of remote sensing camera and informatics theory, information entropy is presented as the automatic exposure criteria for remote sensing camera and its performance is detailedly analyzed. Aiming at the characteristics of gray-level histogram at different exposure time and the relationships between image brightness and information entropy, improved MCS (Mountain Climbing Servo) is proposed to approach the optimal exposure time in short order. The proposed algorithm has been successfully tested to be effective on a subminiature CMOS remote sensing camera system developed by the authors. Experimental results demonstrate that the proposed criteria can adjust the exposure time automatically according to the image information with high speed, sensitivity and reliability. It is of great value for CMOS camera to improve the quality of space imaging.