Phase unwrapping via hierarchical and balanced residue partitioning

Branch cut placement is an important issue in 2D phase unwrapping. The main requirement is to get the shortest branch cut placement with a minimum isolated area. We present a branch cut placement method that is based on hierarchical balanced partitioning (HBP) of the residue map. The method has two stages. In the first stage, the balanced residues which are one pixel or two pixels apart are connected. In the second stage, the remaining residues are processed via hierarchical and balanced partitioning of the residue map and subsequent serial connection. The method considers both local and global positioning of the residues and in this respect produces better results compared to the well-known conventional Goldstein method where the residue groups are connected based on local considerations only with respect to branch-cut length, and isolated area. The proposed method is also compared with the combined and extended methods based on residue searching, phase unwrapping max-flow method, exchange algorithm, minimum-cost matching theory, and hybrid genetic algorithm by using different types and sizes of wrapped input images. The implementation of the proposed method and the RMSE values are also comparable.