Defocus Map Estimation From a Single Image Based on Two-Parameter Defocus Model.

Defocus map estimation (DME) is highly important in many computer vision applications. Nearly, all existing approaches for DME from a single image are based on a one-parameter defocus model, which does not allow for the variation of depth over edges. In this paper, a novel two-parameter model of defocused edges is proposed for DME from a single image. We can estimate the defocus amounts for each side of the edges through this proposed model, and the confidence that the edge is a pattern edge, where the depth remains the same over the edge, can be generated. Then, we modify the TV-L1 algorithm for structure-texture decomposition by taking advantage of this confidence to eliminate pattern edges while preserving structural ones. Finally, the defocus amounts estimated at the edge positions are used as initial values, and the structure component is employed as a guidance in the following Laplacian matting procedure to avoid the influence of pattern edges on the final defocus map. Experiment results show that the proposed method can effectively eliminate the influence of pattern edges compared with the state-of-art method. Furthermore, the estimated defocus map is feasible in applications of depth estimation and foreground/background segmentation.