Information indicating the correspondence relationship of imaging conditions, the thickness of an object, and the thickness of a specific composition included in the object, and a contrast correction amount is stored. The thickness of the object and the thickness of a specific composition included in the object of each unit region having one or two or more pixels of the radiation image are acquired. For each unit region of the radiation image, a contrast correction amount corresponding to a combination of the imaging conditions, the thickness of the object acquired for the unit region, and the thickness of the specific composition is acquired with reference to the stored information indicating the correspondence relationship, and contrast correction is performed using the acquired contrast correction amount.
