| abstract |
In a radiation image recording system using a stimulable phosphor in which a radiation image is once recorded and then read out by use of stimulating rays impinging thereupon, the gradation of the image is processed by setting the read out level of the read out system and by setting the gain of the read out system. Among the image signal read out from the stimulable phosphor, the maximum Smax, the minimum Smin and the average S are determined. When logSmax-logSmin is less than a predetermined value, Smin is made a standard input signal. When it is more than the predetermined value, S or (logSmax+logSmin)/2 is made a standard input signal. The standard input signal is read out as a predetermined level of a standard output signal. Further, the gain of amplification in the image read out system is controlled to be Δs/(logSmax-logSmin) in the former case, and is fixed in the latter case, where Δs is a reproduced signal region. |