Research on automatic focusing technique based on image autocollimation

According to accuracy requirements of aerial camera focusing and characteristics of CCD camera imaging, this paper proposed automatic focusing system of aerial camera based on image processing technology. Firstly, in accordance with self-made resolution target, image sharpness function and optimization of hill climbing algorithm, autocollimation defocusing compensation method was used to achieve correction of the aerial camera defocus caused by temperature and atmospheric pressure. Then the amount of defocus was calculated by introducing the aircraft height data, and defocus adjustment was realized by appropriate device. Finally, the experiment was carried out for simulating and testing of the system, and the results showed that: error of the system for camera defocusing correction is less than half of the camera focal depth, which can meet the requirements of the aerial camera, such as fast, high-precision focusing and so on.