| 摘要 |
PURPOSE:To decide an area decided with a differential value and a threshold value as an irradiation field, by finding the differential value between adjacent picture data from read picture information, comparing the differential value with the threshold value, and scanning it in two directions. CONSTITUTION:Firstly, a cumulative phosphor sheet 10 is scanned by prereading excitation light, and a stimulated excitation beam of light generated from the sheet 10 is read by a photoelectric means. The differential value between a digital picture data obtained in such way and the adjacent picture data is found, and the differential value is compared with the prescribed threshold value Th. Then, as for a a direction of X-axis, change points are generated at the point where it changes from out of the irradiation field to the irradiation field (over +Th), and the point where it changes from the irradiation field to the out of the irradiation field(less than -Th). By deciding the point at every scanning line, two vertical lines are expressed, and the area sandwiched with the two vertical lines is decided as the irradiation field in the direction of X-axis. As for a direction of Y-axis, it is possible to decide the irradiation field by comparing the differential value with the threshold value Th similarly.
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