Development of Defect Detection Algorithm for Surface Inspection System Using Twin Illumination and Subtraction Technique

Surface inspection of steel products is very important for quality assurance. Many automatic in-line surface inspection systems using camera techniques have already been installed in steel sheet production lines. However, automatic surface inspection of steel products such as steel pipes and plates has not advanced because the entire product surface is covered with uneven mill scale, and it is difficult to distinguish the pattern of the mill scale from defects with concave-convex shapes in images captured by a camera.