Dealing With Parallax in Shape-From-Focus

We propose a new method that extends the capability of shape-from-focus (SFF) to estimate the depth profile of 3-D objects in the presence of structure-dependent pixel motion. Existing SFF techniques work under the constraint that there is no parallax in the captured stack of frames. However, in off-the-shelf cameras, there can be appreciable pixel motion among the observations when there is relative motion between the object and the camera. In such a scenario, the depth estimates will be erroneous if the parallax effect is not factored in. Our degradation model accounts for pixel migration effects in the observations due to parallax resulting in a generalization of the SFF technique. We show that pixel motion and defocus blur therein are tightly coupled to the underlying shape of the 3-D object. Simultaneous reconstruction of the underlying 3-D structure and the all-in-focus image is carried out within an optimization framework using local image operations. The proposed method when tested on many examples, both synthetic and real, is very effective and delivers state-of-the-art performance.