A new PDE-based resolution enhancement technique for the analysis of low SNR particle displacement images

• Published in: European journal of mechanics, B, Fluids Vol. 85; pp. 289 - 311
• Main Author: Mohseni, Arman
• Format: Journal Article
• Language: English
• Published: Elsevier Masson SAS 01.01.2021
• Subjects: Background-Oriented Schlieren (BOS); Denoising; Particle Image Velocimetry (PIV); Poisson’s equation; Speckle displacement; Super-resolution; Background-Oriented Schlieren (BOS); Particle Image Velocimetry (PIV); Super-resolution; Speckle displacement; Poisson’s equation; Denoising
• ISSN: 0997-7546; 1873-7390
• DOI: 10.1016/j.euromechflu.2020.10.002

Speckle images have found multiple applications in image-based measurement techniques, where the objective of measurement is the estimation of speckle displacements between two often consecutive images. Depending on the characteristics of a measurement system and its measurands, the signal-to-noise ratio (SNR) of recorded images may become low and even marginal. One solution to improve the accuracy of speckle displacement estimation in such cases is the use of super-resolution methods. In this article a robust and versatile partial differential equation based resolution enhancement method is presented for the analysis of low SNR speckle displacement signals. The application of the method to synthetic one-dimensional and two-dimensional signals as well as actual particle displacement images indicate that the method is capable of reducing noise effects and partially recovering lost correlation, which in turn makes the selection of smaller interrogation windows and achieving higher resolution and accuracy of displacement estimation possible. The method is applicable to both speckle and particle displacement images.