The state of the art of weld seam radiographic testing Part I, image processing

Over the past 30 years, a large amount of research has been conducted to develop an automatic (or semiautomatic) system for the radiographic detection and classification of discontinuities in continuous welds. There are two major types of research in this field: image processing, which consists of improving radiographic image quality and segmenting regions of interest in the images, and pattern recognition, which aims at detecting and classifying the discontinuities segmented in the images. Because of the complexity of the problem of detecting weld discontinuities, a large number of techniques have been investigated in these areas. This paper represents a state of the art report on weld testing and is divided into separate parts on image processing and pattern recognition. The techniques presented are compared at each basic step of system development for the identification of discontinuities in continuous welds. This part deals with image processing.