NDTnet 1998 Aug, Vol.3 No.8

Abstract

Introduction


Figure 1: Defect: Lack of penetration Figure 2: Region segmentation Figure 3: Boundary extraction

Due to the degraded quality and the small size of the defects, X-ray films aresometimes difficult to inspect. The interpretation of such images is often likely to be affected by a certain human operator's subjectivity. It seems very interesting to introduce techniques that are operator independent.

The aim of this work which enter in a research project on NDT, is to conceive an aid system for interpretation and taking decisions, on imperfections in metallic fusion welds.We have studied and tested several segmentation techniquesbased on the two approaches ( edge and regions )(1).A quantitative analysis (2) will be applied to extract somerelative geometrical parameters. To the sight of thesecharacteristics, a first classification will be possible.

Algorithm and Results
We proceed as follow:

• Acquisition and digitising of an image radiogram, coded on 256 grey scale (Figure 1).
• Pre-processing ( noise reduction, contrast stretching for enhancing the image quality.
• Region segmentation to put failures in obviousness and defect selection (Figure 2).
• Contour following of the defect to extract some geometrical characteristics (Figure 3).
• Decision on the nature of the defect for a first classification.

References
1. N.R.Pal, S.K.Pal A review on image segmentation techniques; Pattern recognition, 1993 Vol 26, N° 9: 1277-1294.
2.Y. Cherfa, Y. Kabir, R. Drai, Analyse de defauts de soudures par traitements d'images, Maghreb in Conference on NDT, June 199 7, Algiers, 138-14 7.
3. Lavayssiere et al, CND par radiographie et traitement de Vinformation. 15eme colloque ETSI, Juan-Les-Pins, Sep. 1995, 1267-1270.

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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