| 摘要 |
PROBLEM TO BE SOLVED: To detect minute defects such as chips and cracks at the mouth part of a container with accuracy. SOLUTION: The circular image of the mouth part of a container is once stored in image memory 3, and then its part is horizontally or vertically scanned by a scanning means 4 and is binarized by a binarizing means 5. A change point detecting means 6 detects the coordinates of the rising point and falling point of every scanning line, and a width detecting means 7 obtains the difference between both of them as a width. The obtained width is compared with a reference value predetermined by the location of the circular image. Thereby, it becomes possible to detect even a defect in which changes in the local inclination of a visual outline are small.
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