Digital image processing has become a key technology in the area of manu­ facturing and quality control. Increasing quality demands require inspection of every single part, which in turn will lead to a much more widespread use of automatic visual inspection systems in the near future. Furthermore, the documentation requirements of ISO 9000 and similar quality control standards can only be met by fully automated, networked inspection systems. On the other hand, despite a multitude of successful applications, digital image processing has not yet established itself as an accepted element of man­ ufacturing technology. This holds true for the industrial practice as well as for the training of engineers. Digital image processing is still widely regarded as some kind of secret lore, mastered only by a small number of expensive -- experts. This impression of incomprehensibility frequently leads to the accusation of unreliability. The manufacturers of digital image processing systems in the industry are not least responsible for this state of affairs, due to their policy of giving the customer as little information as possible about the methods and technology used to inspect his products.