Comparative analysis of interferogram noise filtration using wavelet transform and spin filtering algorithms

Abstract

The aim of this paper is to analyze 2D fringe pattern denoising performed by two chosen methods based on quasi-1D two-arm spin filter and 2D discrete wavelet transform (DWT) signal decomposition and thresholding. The ultimate aim of this comparison is to estimate which algorithm is better suited for high-accuracy measurements by phase shifting interferometry (PSI) with the phase step evaluation using the lattice site approach. The spin filtering method proposed by Yu et al. (1994) was designed to minimize possible fringe blur and distortion. The 2D DWT also presents such features due to a lossless nature of the signal wavelet decomposition. To compare both methods, a special 2D histogram introduced by Gutman and Weber (1998) is used to evaluate intensity errors introduced by each of the presented algorithms.

Comparison of Methods for Determining the Contrast Distribution in Interference Images with Speckle Noise

“…The speckle noise can be diminished by means of optical methods [4,5] as well as numerical ones [6][7][8], but it cannot be totally eliminated. Determining the contrast distribution is one of the main stages of transforming the images obtained by the optical methods into the distribution of a given measured quantity, described by a scalar, vector, or tensor field.…”