Improving Shape From Focus Using Defocus Cue

The shape-from-focus (SFF) method uses a sequence of frames to estimate the structure of a 3-D object. Its accuracy depends on the step size by which the translational table is moved while capturing the images. Existing SFF algorithms use an ad hoc interpolation strategy to account for the error due to the finite step size. We propose an improved SFF method that uses relative defocus blur derived from actual image data to arrive at the final estimates of the structure of the object. A space-variant image restoration scheme is also proposed to obtain a focused image of the 3-D object. The reconstructed 3-D structure as well as the quality of the restored image are superior for the proposed method in comparison to traditional SFF.