1. A method of processing a radiographic image in a radiographic image recording system in which a stimulable phosphor plate is exposed to X-rays passing through an object to record a radiographic latent image of the object in the form of energy of X-rays stored therein, the stimulable phosphor plate is then exposed to stimulating rays to emit light according to the energy of X-rays stored therein, the emitted light is detected by a photodetecting means and converted to an image signal and the image signal is used for recording a visible image on another recording material, said processing method comprising recording images of the same object from the same direction on a plurality of said stimulable phosphor plates, superposing the image signals obtained from the plurality of stimulable phosphor plates to obtain an image signal having averaged image information, and enhancing the contrast of said image signal thus obtained by a gradation processing.