Applications of Digital Image Enhancement Techniques for Improved Ultrasonic Imaging of Defects in Composite Materials

Abstract

Several standard digital image enhancement techniques have been applied to digitized ultrasonic C-scan images of defects in graphite/epoxy composites. Features in the computer enhanced images are much more distinct than those in the original images. In some cases, cracks which are too close together to be visually resolved in the original images are clearly resolved in the enhanced images. Noisy images have been improved by first smoothing the original data and then edge enhancing the smoothed data. The resulting sharpened edges improve the visualization of features in the images. The application of digital image enhancement techniques has allowed the imaging of defects in composite materials at frequencies as low as 3.5 MHz. This use of these lower frequencies permits better imaging of defects in thick composite materials. INTRODUCTION