Abstract: In order to reliably detect a defect on an inspected surface, electronic pictures of the inspected surface are formed at different positions by moving an imaging area relative to the inspected surface. Defect candidate regions are extracted from a series of the pictures. The system examines whether a movement from one candidate region to another candidate region is proportional to the movement of the imaging area. If the movement between the candidate regions is in proportion to the movement of the imaging area, the system judges that the candidate regions are imagery of a defect on the inspected surface.

Abstract: A surface defect inspection apparatus a lighting unit shaped in an arched form laid across the path of movement of an object under inspection for illuminating its surface. A light diffusion sheet is located between the lighting unit and the path of movement of the object for forming a bright and dark light pattern on the surface of the object. A plurality of light sensors are arranged in an arched form laid across the path of movement of the object. Each of the light sensors produces an electrical signal in response to light of reflection from the surface of the object. The electrical signal is converted into an image including the bright and dark light pattern. This conversion is repeated to produce similar images in sequence for inspection of a defect which may exist on the surface of the object.