Global approaches and local strategies for phase unwrapping

Guerriero, L. and Refice, A. and Stramaglia, S. and Satalino, G. and Veneziani, N. and Blonda, P. and Pasquariello, G. and Chiaradia, M.T. (2001) Global approaches and local strategies for phase unwrapping. Il nuovo cimento C, 24 C (1). pp. 205-222. ISSN 1826-9885

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Phase unwrapping, i.e. the retrieval of absolute phases from wrapped, noisy measures, is a tough problem because of the presence of rotational inconsistencies (residues), randomly generated by noise and undersampling on the principal phase gradient field. These inconsistencies prevent the recovery of the absolute phase field by direct integration of the wrapped gradients. In this paper we examine the relative merit of known global approaches and then we present evidence that our approach based on “stochastic annealing” can recover the true phase field also in noisy areas with severe undersampling, where other methods fail. Then, some experiments with local approaches are presented. A fast neural filter has been trained to eliminate close residue couples by joining them in a way which takes into account the local phase information. Performances are about 60–70% of the residues. Finally, other experiments have been aimed at designing an automated method for the determination of weight matrices to use in conjunction with local phase unwrapping algorithms. The method, tested with the minimum cost flow algorithm, gives good performances over both simulated and real data.

Item Type: Article
Additional Information: Paper presented at the Workshop on Synthetic Aperture Radar (SAR), Florence, 25-26 February, 1998. Support for this work was provided through a post-doc grant by the Istituto Nazionale di Fisica della Materia (INFM).
Uncontrolled Keywords: Image processing ; Neural networks, fuzzy logic, artificial intelligence ; Numerical optimization
Subjects: 500 Scienze naturali e Matematica > 550 Scienze della Terra
Depositing User: Marina Spanti
Date Deposited: 10 Mar 2020 18:12
Last Modified: 10 Mar 2020 18:12

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