An Image Enhancement Technique for Ultrasonic NDE of CFRP Panels

This paper discusses an image enhancement technique based on a standard deviation method to obtain high contrast C-scan results by using immersion ultrasonic testing. Ultrasonic C-scan results have relatively low resolution and poor imaging quality in anisotropic composites due to the speckle noise produced by the interference of backscattered signals. This developed technique will aid non-destructive evaluation (NDE) inspectors in making quick, accurate, and reliable decisions. A high quality region of interest (ROI) image was first reconstructed from the raw amplitude data obtained from ultrasonic testing. Then, a standard deviation based method was applied on ROI images to improve the edge contrast of the defect area to the non-defect area. The results obtained demonstrated that this applied method can greatly improve the image quality and offer detailed information of defects in an ROI by restraining the noises effectively. We believe this technique can make the defect evaluation process much easier and more accurate, and it can be expected to be a novel method for the ultrasonic C-scan result enhancement.