Defect inspection method and apparatus

A defect inspection apparatus comprising:

• an image acquisition unit obtaining an image of an inspection object by imaging the inspection object having a pattern thereon;
• a reference image generation unit generating a reference image that does not include a defect from the image of the inspection object obtained by the image acquisition unit and generating a multi-value mask for masking a non-defective pixel from the obtained images of the inspection object;
• a feature amount computing unit calculating a defect accuracy by matching the brightness of the image of the inspection object obtained by the image acquisition unit and the reference image generated by the reference image generation unit;
• and
• a defect detection processing unit detecting the defect by comparing the defect accuracy calculated by the feature amount computing unit with the multi-value mask generated by the reference image generation unit.

An ultrasonic inspection apparatus comprising:

• a detection unit comprising an ultrasonic probe emitting an ultrasonic wave and a flaw detector detecting a reflected echo generated from an inspection object by the ultrasonic wave emitted from the ultrasonic probe;
• an A/D conversion unit A/D converting a signal output from the flaw detector having detected the reflected echo in the detection unit;
• and
• an image processing unit processing a signal output from the flaw detector which has detected the reflected echo and converted into a digital signal by the A/D conversion unit, generating a sectional image in a plane parallel to a surface of the inspection object inside the inspection object, processing the generated internal sectional image, and thereby inspecting an internal defect of the inspection object, wherein
• the image processing unit comprises:
• a sectional image generation unit detecting the reflected echo generated from the flaw detector, processing the output signal, and generating the sectional image of the inside of the inspection object;
• a reference image generation unit generating a reference image that does not include a defect from the sectional image of the inside of the inspection object generated by the sectional image generation unit and generating a multi-value mask for masking a non-defective pixel from the obtained internal image of the inspection object;
• a feature amount computing unit calculating a defect accuracy by matching the brightness of the internal sectional image of the inspection object generated by the sectional image generation unit and the reference image generated by the reference image generation unit;
• a defect detection processing unit detecting the defect by comparing the defect accuracy calculated by the feature amount computing unit with the multi-value mask generated by the reference image generation unit;
• and
• an output unit outputting the internal defect detected by the defect detection processing unit.