A plurality of original image signals representing radiation image information, which have been fed out from an image signal input apparatus, are fed into an operation processing device. Predetermined operation processing is performed on the plurality of the received original image signals in the operation processing device to obtain an operation-processed image signal. Also, at least one original image signal, which is among the plurality of the original image signals, is transferred to an image output device. Image outputting is performed with the image output device and in accordance with the one original image signal having been transferred. After the operation-processed image signal has been obtained from the predetermined operation processing, the operation-processed image signal is fed into the image output device, and image outputting is performed with the image output device and in accordance with the received operation-processed image signal.