Design and implementation of a metal surface defect image acquisition system

A high speed, high resolution surface defect image acquisition system has been designed and implemented. The system was designed to acquire images of a wide, moving metal surface. The goal of the system is to show the factory operators the location and the shape of surface defects. Since the size of a defect is very small and the area of inspection is very large, a great amount of pixel data should be handled within a short time. In order to achieve this requirement, a large amount of data reduction is needed. The system consists of a set of CCD linescan cameras, a line image processing system, and a workstation. Among the components of the system, lighting and multicamera system are the most important parts. Six high resolution linescan cameras are used to obtain more than twenty thousand pixels per each line. The line image processing unit consists of a camera controller, frame grabbers, and defect image modules. In order to reduce the data drastically, run-length-encoding scheme was used - encoding only the locations of possible defects. These programs were implemented with FPGA chips. We show our implementation details in this paper.