12 December 1994 New methods for unwrapping noisy phase maps
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An algorithm for unwrapping noisy phase maps has recently been proposed, based on the identification of `discontinuity sources' which mark the start or end of a 2(pi) phase discontinuity. Branch cuts between sources act as barriers to unwrapping, resulting in a unique phase map, independent of the unwrapping route. Five methods to optimize the placing of the cuts are described. The most successful is one based on a global minimization of the total cut length, using a graph theory `maximum flow' algorithm. Computation time increases approximately as the square of the number of sources. With this approach, unfiltered speckle interferometry phase maps with very high discontinuity source densities (at least 0.1 sources pixel-1) can be reliably unwrapped. An alternative method based on a one- dimensional unwrapping along the time axis is also described. The main advantages of this second technique are (1) it is inherently simple, (2) phase errors are constrained within the high noise regions, and (3) phase maps containing global discontinuities are unwrapped correctly, provided the positions of the discontinuities remain fixed with time.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Jonathan Mark Huntley, Jonathan Mark Huntley, } "New methods for unwrapping noisy phase maps", Proc. SPIE 2340, Interferometry '94: New Techniques and Analysis in Optical Measurements, (12 December 1994); doi: 10.1117/12.195900; https://doi.org/10.1117/12.195900

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