IMAGE ENHANCEMENT FOR RADIOGRAPHIC NON-DESTRUCTIVE INSPECTION OF THE AIRCRAFT
Xin Wang, Brian Stephen Wong, Chen Guan Tui, Kai Peng Khoo, Frederic Foo · 2006
Traditional radiography is a non-destructive inspection (NDI) process widely used for the detection of cracks and damage in aircraft structures. However a significant limitation is that it relies on visual assessment by the operator for identification of defects from the radiographic image. Digital radiography allows all the benefits of producing significant increases in magnification and image clarity, as well as efficient management of digital images. Image enhancement allows more accurate interpretation of digital radiography indications. In this paper, image enhancement methods are investigated for NDI inspection of the aircraft. The wavelet thresholding technique is applied to reduce the radiographic image noise. The contrast and brightness of the image is adjusted using gamma correction and contrast limited adaptive histogram equalization to enhance perception of defects. These are used to eliminate noise and background artifacts and to smooth sharp edges, but also tend to remove some of the detail in small objects. 1.