Improved image analysis based corrosion assessment using preprocessing techniques

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Pakrashi, Vikram
Schoefs, Franck
Memet, Jean Bernard
O'Connor, Alan J.
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The importance of non-destructive techniques (NDT) in structural health monitoring programmes is being critically felt in the recent times. The quality of the measured data, often affected by various environmental conditions can be a guiding factor in terms usefulness and prediction efficiencies of the various detection and monitoring methods used in this regard. Often, a preprocessing of the acquired data in relation to the affecting environmental parameters can improve the information quality and lead towards a significantly more efficient and correct prediction process. The improvement can be directly related to the final decision making policy about a structure or a network of structures and is compatible with general probabilistic frameworks of such assessment and decision making programmes. This paper considers a preprocessing technique employed for an image analysis based structural health monitoring methodology to identify sub-marine pitting corrosion in the presence of variable luminosity, contrast and noise affecting the quality of images. A preprocessing of the gray-level threshold of the various images is observed to bring about a significant improvement in terms of damage detection as compared to an automatically computed gray-level threshold. The case dependent adjustments of the threshold enable to obtain the best possible information from an existing image. The corresponding improvements are observed in a qualitative manner in the present study.
Image processing , Probability of detection , Probability of false alarm , Non destructive techniques
Pakrashi, V., Schoefs, F., Memet, J. B. & O'Connor, A. (2008). Improved image analysis based corrosion assessment using preprocessing techniques. MEDACHS 08 (Marine Environment Damage to Atlantic Coast Structures and Buildings: Methods of Assessment and Repair) 1st International Conference, Construction Heritage in Coastal and Marine Environments: Damage, Diagnostic, Maintenance and Repair. Lisbon, Portugal 28-30 Jan 2008.