The automated inspection of moving webs using machine vision

Many materials are manufactured industrially in the form of a continuously moving strip or web; examples include metal strip (cold rolled, plated and stainless steel; aluminium), paper, glass, textile materials (woven, knitted and printed fabric; lace; carpet), etc etc. To ensure high product quality it is necessary to inspect visually,; this inspection can be automated using machine vision. The motivations include increased cost effectiveness, much higher operating speeds, reliability, consistency and objectivity, and improved record keeping. For some applications, automated inspection using machine vision is already operational; other cases remain to be conquered. This paper discusses progress in the application of machine vision to automate web material inspection, concentrating on the development of a generalised theory for signal processing for defect detection. Limitations to the present state-of-the-art in machine vision inspection are considered. It is suggested that the dominant factor limiting the spread of machine vision inspection in industry is cost effectiveness