An image acquisition unit acquires first and second radiation images from first and second radiation detectors. A first frequency analysis unit generates a first high-frequency component and a first low-frequency component of the first radiation image, and a second frequency analysis unit generates a second low-frequency component of the second radiation image. A subtraction processing unit generates a subtraction low-frequency component from the first low-frequency component and the second low-frequency component, and a synthesis unit synthesizes the subtraction low-frequency component and the first high-frequency component to generate a processed image.
