PROBLEM TO BE SOLVED: To provide a technology for achieving noise reduction processing with higher accuracy without increasing a processing time in photographing the same subject with a plurality of frames while changing projection angles.SOLUTION: A plurality of projection images of a subject photographed by irradiating radiation to the subject from respectively different angles are acquired. A first determination area obtained by centering a target pixel is set in a first search area obtained by centering the target pixel in a first projection image. A pixel where the same object as the target pixel is projected is specified from a second projection image, and a second search area obtained by centering the pixel is set. Similarity between an area obtained by centering each pixel and the first determination area is acquired about each pixel in the first and second search areas, and weighting to a pixel value of the pixel is performed by using a weighted value which takes a smaller value as the similarity becomes large. A pixel value of the target pixel is updated by using the total value of pixel values which undergo weighting about each pixel in the first and second search areas.SELECTED DRAWING: Figure 4
