Adaptive focusing method based on depth-of-field estimation

Aiming at the autofocus requirements of lenses with variable aperture and focal length, this paper proposes an autofocus method based on depth-of-field estimation to adaptively calculate the search step length and adjust the focusing region. First, based on the relationship between the focus curve broadening and the existence of depth-of-focus, the search step size during coarse focusing is adaptively calculated by depth-of-focus estimation, so that the motor quickly approaches the focusing peak. Second, using the clarity data obtained during the adaptive step-size search, the direction of object space extension can be estimated, so that focusing region optimization can be performed to improve the peak shift of the focus curve in the state of small depth-of-field. Finally, the hill-climbing search method with small step length is used to realize accurate focusing. Experiments show that compared with the traditional hill-climbing search methods and the coarse-to-fine search methods, this method can reduce the number of focus searches by about 35% through adaptive focusing method, thus speeding up the focusing speed, and can improve the focusing reliability in the case of small depth-of-field through region optimization.