Means of eliminating background effects for defect detection and visualization in infrared thermography

Pulse infrared thermography is renowned as an effective and rapid method of nondestructive inspection. The primary difficulty in making useful interpretations of a thermal image is the presence of extraneous effects such as thermal noise, optical distortion through the thermal imaging system, and of...

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Bibliographic Details
Published in:Optical Engineering 2000-04, Vol.39 (4), p.879-884
Main Authors: Plotnikov, Yuri A, Rajic, Nik, Winfree, William P
Format: Article
Language:English
Subjects:
backgrounds
defect detection
image analysis
infrared thermography
nondestructive testing
trend removal
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Summary:Pulse infrared thermography is renowned as an effective and rapid method of nondestructive inspection. The primary difficulty in making useful interpretations of a thermal image is the presence of extraneous effects such as thermal noise, optical distortion through the thermal imaging system, and of most concern, non-uniform heating through the uneven excitation of the surface. A means for removal of background trends caused by uneven illumination is presented. It is based on a polynomial fitting technique applied to a rectangular infrared image on a line-by-line basis in either horizontal or vertical directions. The polynomial coefficients are found by choosing three key pixels through a conditional iterative technique. The proposed algorithm enables improvements in flaw visibility and assists the effective application of additional image processing techniques. The procedure is found to remove trends without distorting real flaw indications as long as the indication spans less than 67 of the interval under examination. ©
ISSN:0091-3286
1560-2303
DOI:10.1117/1.602460