Enhancement of phase detection for autofocus
Phase detection autofocus (PDAF) is a technique that uses sensors on left and right pixels to determine the relative position between the object and the focal plane. When an image is out of focus, a shift between the assembled left and right pixels is resulted, which can be used to determine the lens movement during the autofocus process. However, the presence of noise and blur often affects the accuracy of shift estimation and hence the performance of autofocus. In this paper, we propose a method to enhance phase detection for such sensors. A Gaussian filter is applied to overcome the adverse effect of image noise and blur. Experiments are conducted to show that the proposed method leads to a more accurate estimate of lens movement than the traditional phase correlation.