The aim is to reduce manning-levels in quality control. In the quality assurance techniques of a production line, it is proposed that the evaluation of data shall in future be done automatically by implementing digital image processing, where optical information are turned into electrical signals. The results will, in comparison with the present state of image-analysing, be safer and more reproducible. With an expert system, welding procedures may be controlled while the feasibility of finding defects, including their classification and evaluation will be studied.