A first image signal representing a radiation image of an object is obtained by exposing a stimulable phosphor sheet, on which the radiation image has been stored, to stimulating rays, which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation, the emitted light being detected. A second image signal representing the radiation image is thereafter obtained by again exposing the stimulable phosphor sheet to stimulating rays, the light emitted by the stimulable phosphor sheet being detected. Read-out conditions, under which the second image signal is to be obtained, and/or image processing conditions, under which the second image signal having been obtained is to be image processed, are adjusted on the basis of the first image signal. A storage device stores information representing a standard pattern of radiation images. A signal transforming device transforms the first image signal representing the radiation image into a transformed image signal representing the radiation image, which has been transformed into the standard pattern. A condition adjuster is provided with a neural network, which receives the transformed image signal and feeds out information representing the read-out conditions and/or the image processing conditions.