| 摘要 |
PROBLEM TO BE SOLVED: To simplify the inspection of the surface state of a circumferential wall face of a through hole in a through hole plate and to enhance the accuracy of the inspection. SOLUTION: Regarding a first main face (a main face on the side where an opening area is wide) and a second main face (a main face on the side where opening area is narrow) on a shadow mask SM, a prescribed number of first main-face gradation data and second main-face gradation data are obtained from a live image. Both image data are shading-corrected (S132 to S137), and a noise which is caused by a light source or the like is removed. Then, the first main-face gradation data which has been corrected is divided by the second main-face gradation data (S139), and offset gradation data in which data corresponding to the second main-face gradation data has been offset from the first main-face gradation data, is obtained. The offset gradation data is smoothed and processed by a median filter which comprises 31×31 filter windows, and median data which has been smoothed is obtained (S140). After that, the offset gradation data is divided by the median data, standardized data is found (S141), an image is displayed on the basis of the standardized data (S142), and an image from which the grade of the shadow mask SM has been removed and in which an irregularity in light transmittance has been emphasized is displayed.
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