DEFECT INSPECTION SYSTEM, DEFECT INSPECTION METHOD, AND DEFECT INSPECTION PROGRAM FOR WOOD PLANK

A light 2 for reflected light that emits visible light for reflected light onto a front side of a veneer 6, a light 32 for invisible light that emits near-infrared light for transmitted light onto a back side of the veneer 6, and an image processing device 1 that detects defects of the veneer 6 by analyzing a captured image generated by a line sensor camera 4 are provided. Defects of the veneer 6 are discriminated on the basis of a set of shading and shapes in an infrared-transmitted-light image based on the transmitted light, and colors in a visible-light image based on the reflected light. Consequently, even if a defect has a small color difference from a normal part in the visible-light image, difference of shading between the defective part and the normal part appears in the infrared-transmitted-light image, and a defect that is difficult to detect by seeing only a color difference in a visible-light image can be relatively easily detected.