Patent ID: 8086024

Claim:
A defect detection apparatus for detecting a defect on an image-picked-up object surface from a multi-valued image picked up by an image pickup device, the apparatus comprising: a size setting accepting device for accepting setting of a size of a defect as a detection object; a size setting device for setting the defect size accepted by the size setting accepting device; a reduction ratio setting device for setting an image reduction ratio in accordance with the defect size set by the size setting device; an image reducing device for generating a reduced image obtained by reducing the multi-valued image at the image reduction ratio; a filter processing device for performing filter processing on the reduced image for removing a defect in the reduced image; an image enlarging device for generating an enlarged image obtained by enlarging the reduced image, subjected to the filter processing by the filter processing device, at an image enlargement ratio corresponding to the reciprocal of the image reduction ratio; and a difference calculating device for generating a difference image obtained by performing a calculation of a difference between the multi-valued image and the enlarged image.