Inferring three-dimensional (3D) shape of real objects from visual information belongs to the main domain of the computer vision applications. Shape From Focus (SFF) is one of the passive methods that uses focus as a cue to infer the 3D structure of the object. In SFF, the objective is to find out the depth by measuring the distance of well-focused position of each object point from the camera lens. A sequence of images is acquired either by displacing the object in small steps or by changing the focal length of the lens in the camera. First, a focus measure, which is a criterion that can...