The optimization and design of the auto-exposure algorithm based on image entropy

In order to make the CMOS image sensor exposure automatically and correctly in different environment, this paper presents an improved algorithm based on image entropy. Image entropy is the information measure of image. Thus, with the purpose of getting the most appropriate exposure time, we can search the maximum information entropy. What´s more, by using the formula manipulation of image entropy and the piecewise linearization of the log function, the algorithm grasps the overall change rule and avoids the traditional precise calculation, which can save the computing time greatly and reduce the use of the resource. Meanwhile, simulation results demonstrated the effectiveness of the algorithm, which leaves a strong foundation for the hardware realization of the CMOS image sensor auto-exposure.