Single Image Multi-focusing Based on Local Blur Estimation

Abstract

In this paper, we address a challenging problem of multi-focusing image from a single photograph taken with an uncalibrated conventional camera. In order to achieve this, we firstly derive an optical degradation model which enables us to adopt a point operation scheme to realize image multi-focusing. This scheme can effectively reduce halo artifacts in the refocused image and greatly improve the computational efficiency. Then, a two-step approach is applied to estimate the blur map of the input image. i). A sparse blur map is obtained by estimating the amount of defocus blur at edge locations. ii). The guided image filtering method is applied to propagate the value from edge locations into the unknown regions. In order to obtain the depth map of the whole scene to realize the multi-focusing, we adopt a simple geometry prior of photograph to eliminate the ambiguity over the focal plane. Based on the obtained depth map, we can directly produce different styles of images by multi-focusing with the adjustment to the camera parameters. Experimental results on a variety of images show that our method can acquire visual pleasing multi-focusing results. Moreover, our method can also extract the depth map of the scene with fairly good extent of accuracy.