Overall well focused catadioptric image acquisition with multi-focal images: a model based method

When a catadioptric imaging system suffers from limited depth of field, a single image can not capture all the objects with clear focus. To solve this problem, a set of multi-focal images can be used to extend the depth of field by fusing the best focused image regions to an overall well focused composite image. In this paper, we proposed a novel model based method that avoids the computational cost problem of previous extended-depth-of-field algorithms. Based on the special optical geometry properties of catadioptric systems, the proposed model describes the shapes of the best focused image regions in multi-focal images by a series of neighboring concentric annuluses. Then we proposed a method to estimate the model parameters. Based on this model, an overall well focused image is obtained by combining the best focused regions with a fast and reliable online operation. Experiments on catadioptric images of a variety of different scenes and camera settings verify the validity of the model and the robust performance of the proposed method.