Depth from focus (DFF) is a technique to estimate the depth and 3D shape of an object from a sequence of images obtained at different focus settings. The DFF is presented as a combinatorial optimization problem. After the estimate of the initial depth map solution of an object, the algorithm updates the depth map iteratively from the specially defined neighborhood. The results of the proposed DFF algorithm have shown significant improvements in both the accuracy of the depth map estimation and the computational complexity, with respect to the existing DFF methods.