Abnormalities in Ultrasonic (C-Scan) Images of Composite Structures: Impact Damaged Versus Hole Damaged

This paper is about applying image processing to detect different types and levels of damage in composite structures using in C-scan images produced by ultrasonic testing. This method plays an important role as it can detect any discontinuities or flaws in the specimen. To analyze such critical image in an, automated inspection environment an image processing method that correlates Threshold values to Gradient Field values is used to extract important information from the c-scan images in order to detect abnormalities that may exist. The paper presents an improved approach to composite damage characterization using Threshold Level Variation as an input variable to Gradient Fields. Furthermore, the detailed results showed an important dependency between what can be detected and the used threshold level. At each level certain abnormalities appeared. Setting threshold value is proved to be a function of image type and quality, purpose and application.