| 摘要 |
Calculations are made to find the differences, DELTA ij=fij-f0, between the value of an image signal component f0 representing a picture element P0 in a radiation image and the values of image signal components fij representing the picture elements Pij, which are located on each of a plurality of lines Li, where i=1, 2, ..., n, extending from the picture element P0 to the peripheral parts of the radiation image, and which are spaced a plurality of distances rij, where j=1, 2, ..., m, from the picture element P0. A representative value, which is representative of the differences DELTA ij, is then found for each of the lines Li. A mean level value of two representative values for each set of two lines, which extend from the picture element P0 in approximately opposite directions, is then calculated. From the mean-level values, which have been calculated for a plurality of the sets of lines, a judgment is made as to whether the picture element P0 falls or does not fall within the region corresponding to a circular pattern in the radiation image. |
