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A sliding-window transform-domain technique for denoising of DSPI phase maps

We have developed a technique for denoising speckle pattern fringes, which makes use of an overcomplete expansion in transform domain combined with suitable thresholding of transform-domain coefficients related with the speckle size. In this paper, we modify the technique to work on noisy phase maps obtained by Phase Shifting Digital Speckle Pattern Interferometry (PSDSPI). The modified version utilizes a complex-valued representation for the phase maps and consequently employs Discrete Fourier transform in sliding window mode for obtaining the sought overcomplete expansion. We discuss issues related of the window size and local threshold value selection. We compare this approach with two state of the art denoising techniques on simulated speckle pattern phase maps. Furthermore, we demonstrate the performance of our technique for denoising of real phase maps, obtained through PSDSPI in an out-of-plane sensitive set-up.