Multi-scale gapped smoothing algorithm for robust baseline-free damage detection in optical infrared thermography

Abstract

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A robust multi-scale gapped smoothing algorithm for baseline-free damage mapping from raw thermal images in flash thermography

“…In the original GSA implementation [9], a single pixel is considered for the spatial gap, and its sound behavior is approximated by fitting a cubic polynomial to the gapped pixel's surrounding pixels. However, considering the typical shape of IRT measurements, it was found that a linear fitting polynomial is more appropriate for thermographic datasets [12]. Besides the obvious reduction in the polynomial's order, this also accounts for a large reduction in calculation time.…”

“…This contribution discusses the Multi-Scale Gapped Smoothing Algorithm (MSGSA) [12], which is a novel image processing technique that evaluates a wide range of spatial gap sizes and combines them into a unique damage index map. This multi-scale approach robustly detects defects of different sizes in the presence of non-uniform background and measurement noise.…”

Vibro-Thermal Wave Radar: Application of Barker Coded Amplitude Modulation for Enhanced Low-Power Vibrothermographic Inspection of Composites

“…Especially for composites with high in-plane diffusivity, the latter is of high concern. Proper post-processing of the thermographic dataset is essential in order to ensure maximum detectability [ 3 , 4 , 5 , 6 ]. The test-piece may also be inspected in the transmission mode such that the defects are detected based on the thermal response transmitted to the back surface, which leads to increased detectability of deep defects [ 7 ].…”

Adaptive spectral band integration in flash thermography: Enhanced defect detectability and quantification in composites

“…However, flash thermography is inherently limited by the highly diffusive and strongly damped nature of the induced thermal waves, making the accurate detection of small and deep defects very challenging. Several image processing techniques, which only use the input of one single thermogram, have been developed to enhance the defect detectability by reducing noise and background non-uniformities [6][7][8]. Also many data post-processing techniques, which use the complete recorded thermographic sequence, have been implemented to further enhance the defect detectability [1,[9][10][11][12].…”