Abstract: A plurality of illumination elements configured to irradiate an inspection target region with illumination light obliquely at an identical angle in respective directions different from each other and equiangularly spaced from each other around an image capturing part are sequentially turned on and off. The image capturing part generates a plurality of pieces of captured image data by capturing an image of the target region in a normal direction when each of the plurality of illumination elements is turned on. A determination image generation part generates minimum luminance image data in which a minimum value among luminance values of the plurality of pieces of captured image data at an identical pixel position is set as a luminance value at the pixel position, and then generates determination image data based on the minimum luminance image data. A defect determination part determines existence of a defect based on the determination image data.

Abstract: A plurality of illumination elements configured to irradiate an inspection target region with illumination light obliquely at an identical angle in respective directions different from each other and equiangularly spaced from each other around an image capturing part are sequentially turned on and off. The image capturing part generates a plurality of pieces of captured image data by capturing an image of the target region in a normal direction when each of the plurality of illumination elements is turned on. A determination image generation part generates minimum luminance image data in which a minimum value among luminance values of the plurality of pieces of captured image data at an identical pixel position is set as a luminance value at the pixel position, and then generates determination image data based on the minimum luminance image data. A defect determination part determines existence of a defect based on the determination image data.