| 摘要 |
A statistical processing unit compares the gray levels at identical positions in raw and reference images using a raw image having three or more gray levels obtained by sensing an object by an image pick-up unit. As the reference image, a predetermined designed image or at least one shift image obtained by shifting the raw image by an integer multiple of the repetition period in the repetition direction of a specific pattern is used. The statistical processing unit statistically analyzes the occurrence state of the difference between the raw and reference images, thus accurately obtaining the formation state of repetitive patterns on the object.
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