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Efficient phase-unwrapping algorithm by using phase blocks

: Wang, B.; Lu, T.; Zheng, Z.; Mischo, H.

Wen, T.d.:
3rd International Symposium on Test and Measurement, ISTM/99. Conference proceedings
Beijing: International Academic Publishers, 1999
ISBN: 7-80003-441-0
International Symposium on Test and Measurement (ISTM) <3, 1999, Xi'an>
Conference Paper
Fraunhofer IPT ()
phase unwrapping by blocks; cellular automata; path-dependant phase unwrapping

Phase unwrapping is extensively used in optical measurements where phase-shifting technique is employed. For removing 2 pi-phase jumps resulted from phase computation, path-dependent and path-independent (cellular automata) algorithms for phase-unwrapping are usually employed. The method described in this paper is the phase unwrapping by blocks which combines the advantages of both the path-dependent and the cellular automata algorithms. It determines unwrapping strategy according to the fringe distributions of wrapped phase map, divides the phase map into phase blocks of different sizes and unwraps them by using either path-dependent or cellular automata algorithms. The unwrapped phase maps blocks are then connected into a complete phase map with one line or column of each neighboring block overlapped. A criterion for block divisions and for marking inconsistent data (bad points) is given. The proposed phase-unwrapping method is of high speed in unwrapping as compared with the conventional path-dependent and the path -independent unwrapping rnethods. Computer memories can be saved by use of this method and the method is therefore especially suitable for unwrapping large-sized phase maps.