【摘要】During the last 2 decades, Vision Technology has gradually entered the paper industry. Twenty years ago, a small Finnish Company Roibox developed the first Web Inspection System (WIS) using line scan cameras and, at the time, quite advanced DSP processors to analyze camera signals. In WIS (web inspection systems), cameras are typically placed at the reel just before the winder, in a line across the entire web width. In the beginning it was more or less just about hole detection. Over the years, this technology has experienced one major technology change, this was around the year 2000, when true imaging was introduced and technology was mature enough. Today there are 3 main and some smaller suppliers. Most suppliers use line scan cameras except one main supplier uses area scan cameras. - Today's systems are rather mature and can detect and classify most clearly visible defects. The areas in need of further improvement are low contrast defects and complicated texture art defects.