Method of and apparatus for processing a radiation image

A method of processing a radiation image in a radiation image recording system in which a stimulable phosphor is scanned with a stimulating ray and the radiation image information recorded in the stimulable phosphor is read out and converted into an electric signal upon stimulation thereof and then a visible image is recorded on a recording material by use of the electrical signal, said method comprising a step of conducting an operation represented by a formula

• S'=Sorg+F(X)
• is conducted at every scanning point, where Sorg is the original image signal read out from the stimulable phosphor, Sus is an unsharp mask signal corresponding to a super-low spatial frequency, X is Sorg-Sus, and F(X) is a monotomically increasing function which satisfies the condition of F'(X.sub.1).gtoreq.F'(X.sub.2).gtoreq.0 for arbitrary values X.sub.1, X.sub.2 of X (.vertline.X.sub.1 .vertline.<.vertline.X.sub.2 .vertline.) and in which there exists at least one certain value X.sub.0 of X which satisfies the condition of F'(X.sub.1)>F'(X.sub.2) when .vertline.X.sub.1 .vertline.<.vertline.X.sub.0 .vertline.<.vertline.X.sub.2 .vertline., whereby the frequency component above said super-low spatial frequency is emphasized.