A prototype for an automated visual on-line metal strip inspection system is described. The system is capable of both detecting and classifying surface defects in copper alloy strips, and it has been installed for evaluation in a production line in a rolling mill. The image acquisition part of the system is based on a CCD line scan camera and condensing bright field illuminators. The inspection algorithms are based on morphological preprocessing and combined statistical and structural defect recognition. The image processing hardware consists of commercial modules. An analysis of this implementation is presented. A similar inspection principle has also been successfully applied to steel strip inspection.
Piironen, T., Silven, O., Pietikäinen, M., Laitinen, T., & Strömmer, E. (1990). Automated visual inspection of rolled metal surfaces. Machine Vision and Applications, 3(4), 247-254. https://doi.org/10.1007/BF01211850