| 摘要 |
PROBLEM TO BE SOLVED: To perform as automatic adjustment of contrast and brightness. SOLUTION: The adjustment device of contrast and brightness for getting a scanning image consists of a signal strength distribution forming means for finding signal strength distribution from image data, a cumulative frequency calculating means for finding cumulative frequency from signal strength distribution, a contrast adjusting means for making a coarse contrast adjustment fitting the cumulative frequency indicating a central zone of the signal strength distribution with a central zone of display gradation zone and a fine contrast adjustment fitting the cumulative frequency indicating an end zone of the signal strength distribution with an end zone of the displayed gradation zone through adjustment of a gain of the detector with the cumulative frequency as an index, and a brightness adjusting means for making adjustment of brightness fitting the cumulative frequency indicating an end part of the signal strength distribution with an end part of the display gradation zone through adjustment of a display level with the cumulative frequency as an index. After the central zone of the signal strength distribution is fitted with the central zone in the display gradation zone, the end part of the signal strength distribution is fitted with the end part of the display gradation zone through repetition of fine contrast adjustment and brightness adjustment.
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