Isolation of Defects in Radiographic Weld Images with Wavelet Denoising Using Log-Gabor Filter

Radiography is one of the oldest and most widely used NDT methods for the detection of volumetric defects in welds and castings. Radiographic films are chosen to record the images, due to higher resolution and their flexible usability for any kind of job. When digitized any radiographic image is characterized by three parameters, viz., optical density, contrast, resolution. Of these parameters, resolution of the film depends on the film quality and geometrical unsharpness. The objective of presented work is to compare the radiographic film image acquired at three different resolutions and denoise those images using wavelet technique and to find out the best filter that furnishes the maximum details of the acquired radiographic image. The denoising operation is performed using non orthogonal log-gabor wavelet function. This paves way to decide the best filter to retrieve the information recorded in the radiographic weld images which in turn helps to locate the defects and its dimensions in the corresponding weld piece. Radiographic image offline scattered porosity defect that occurs in weld is taken for this work.