Digital radiography:Digital Radiographic Testing，Dr, for short, is an advanced digital imaging system formed by the combination of computer digital image processing technology and X-ray radiation technology. On the basis of the original X-ray direct film imaging, through a / D conversion and D / a conversion, real-time image digital processing is carried out, and then the image is digitized. It breaks the traditional concept of X-ray and realizes the transformation from analog X-ray image to digital X-ray image. It is a kind of X-ray direct conversion technology. It uses X-ray detector to convert ray information. It has few imaging links, high resolution, clear, delicate image and large dynamic range. In the later stage, it can be edited according to different situations, and it is convenient for transmission and sharing. It is more and more widely used in the industrial field. DR is used in the in-service weld detection, wall thickness corrosion, internal defect detection of steel castings, and structural inspection of electronic components. Dr has a high detection efficiency and reduces labor cost, so it is very popular in automatic production.