Two-dimensional phase unwrapping using a block least-squares method

We present a block least-squares (BLS) method for two-dimensional (2-D) pha se unwrapping, The method works by tessellating the input image into small square blocks with only one phase wrap. These blocks are unwrapped using a simple procedure, and the unwrapped blocks are merged together using one of two proposed block merging algorithms. By specifying a suitable mask, the method can easily handle objects of any shape. This approach is compared wi th the Ghiglia-Romero method and the Marroquin-Rivera method. On synthetic images with different noise levels, the BLS method is shown to be superior, both with respect to the resulting gray values in the unwrapped image as w ell as visual inspection. The method is also shown to successfully unwrap s ynthetic and real images with shears, fiber-optic interferometry images, an d medical magnetic resonance images. We believe the new method has the pote ntial to improve the present quality of phase unwrapped images of several d ifferent image modalities.