Phase shift estimation in interferograms with unknown phase step

We first present two closed formulas for computing the phase shift in interferograms with unknown phase step. These formulas obtain theoretically the exact phase step in fringe pattern without noise and only require the information in two pixels of the image. The previous formulas allows us to define a functional that yields an estimate of the phase step in interferograms corrupted by noise. In the experiment we use the standard Least Square formulation which also yields a closed formula, although the general formulation admits a robust potential. We provide two possible implementations of our approach, one in which the sites can be randomly selected and the other in which we can scan the whole image. The experiments show that the proposed algorithm presents the best results compared with state of the art algorithms.