| 摘要 |
PURPOSE:To reduce the possibility that a detected irradiation field is smaller than an actual irradiation field by not recognizing two points where a differential value exceeds a specific value as contour points as they are, but regarding them as contour candidate points, and deciding that a position between both contour candidate points where the differential value is larger than minimum image data is inside the irradiation field. CONSTITUTION:Differential values delta at respective positions are calculated by primary differentiation and two points Ai and Bi where the absolute value of the differential value is larger than the specific value T0 are regarded as irradiation field contour candidate points on a line Lxn. Then, the minimum value T1 of digital image data on the line Lxn is calculated. Further, two points on both sides of the line Lxn where digital image data is equal to the minimum value T1 are detected as irradiation field contour points Di and Ei on the line Lxn. In other words, it is decided that positions Di-Ei where digital image data is larger than the minimum value T1 are within the irradiation field range on the line Lxn.
|
