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1 April 2003 Spatial-temporal signal processing for subsurface thermographic imaging
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Analysis and processing of thermographic NDT data has been primarily based on either visual analysis of single images acquired during the cooling sequence, or examination of a contrast curve based on comparison to a defect free reference region. Analysis of the sequence is complicated by the fact that the surface temperature of the sample decreases monotonically over a large dynamic range, yet the temperature differences generated by subsurface features may be small by comparison. A simple linearization operation can be performed on the entire sequence so that the time history of each pixel behaves in a manner similar to that of the contrast curve. The linearized data allows visualization of the entire sequence in a fixed dynamic range that is small enough to allow visualization of weak features, as well as presentation of the data in a line slice manner similar to an ultrasonic b-scan.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Steven M. Shepard and James R. Lhota "Spatial-temporal signal processing for subsurface thermographic imaging", Proc. SPIE 5073, Thermosense XXV, (1 April 2003);

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