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Proceedings Paper

Preprocessing of raw data for quality enhancement of the pointwise dynamic speckle analysis
Author(s): Elena Stoykova
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Paper Abstract

The pointwise intensity-based processing of time-correlated speckle patterns allows for detection of activity in threedimensional objects by building a two-dimensional map of a certain statistical parameter. We have developed in this work reliable approaches for high-quality visualization of the activity map through normalization and preprocessing of the captured raw data. As a first task, we analyzed statistical behavior of correlation-based estimates to show erroneous determination of activity under non-uniform illumination or varying reflectivity across the object surface for nonnormalized algorithms and wrong detection of zero-activity regions for the normalized algorithms. Next, we proposed solution for the non-uniform illumination issue by using the sum of the speckle patterns at a given time lag for normalization and by introducing a flexible threshold to form binary patterns. We checked the option of the spatial smoothing of the raw data for activity map visualization enhancement and proved that smoothing in the temporal domain was more effective. Efficiency of the proposed preprocessing for data captured at uniform and non-uniform illumination was demonstrated on synthetic and experimental speckle patterns.

Paper Details

Date Published: 7 September 2018
PDF: 8 pages
Proc. SPIE 10834, Speckle 2018: VII International Conference on Speckle Metrology, 108341O (7 September 2018); doi: 10.1117/12.2319495
Show Author Affiliations
Elena Stoykova, Institute of Optical Materials and Technologies (Bulgaria)

Published in SPIE Proceedings Vol. 10834:
Speckle 2018: VII International Conference on Speckle Metrology
Malgorzata Kujawińska; Leszek R. Jaroszewicz, Editor(s)

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