a hardware processor,

wherein the hardware processor calculates a feature amount relevant to a breast shape from a mammography image, and

the hardware processor selects a schema image corresponding to the breast shape of the mammography image from a plurality of types of predetermined schema images based on the feature amount relevant to the breast shape calculated by the hardware processor:

wherein the feature amount relevant to the breast shape is a feature amount relevant to a volume of a breast included in the mammography image or a feature amount relevant to a position of a nipple;

wherein the feature amount relevant to the volume of the breast is a ratio of a length of a perpendicular line drawn from the nipple to a breast base line in the mammography image to a length of the breast base line.