| 摘要 |
PURPOSE:To ensure the presence or absence decision of an irradiation field diaphragm which prevent the determination of the most suitable reading conditions by preparing the histogram of a picture signal, dividing into plural small areas with using a discriminating reference and detecting the spread of the levels of both sides when while radiating picture information is recorded onto an accumulative phosphor sheet, etc. CONSTITUTION:After a stimulated luminous light from the accumulation type fluorescent material sheet is read by a photo-electric converting means and the picture signal of every picture element is obtained, the histogram is prepared and it is divided into plural small areas by an automatic threshold value selecting method with using the discrimination reference. Next, a small area A to be located on the lowest level side out of the divided small areas is partitioned into a low level partition a1 and a high level partition a2 with a mean picture signal level mua as a boundary the degree of the spread of the picture signal level of the partitions a1 and a2 in a high-low direction is checked, when the spread of the partition a1 is larger, that the irradiation field diaphragm is present is decided and when the partition a2 is larger, that the diaphragm is absent is decided. |
