When an image representing an organ in which an excision region has been identified in such a manner that a blood vessel region in the organ is visually recognizable is generated from a three-dimensional image of the organ, an input specifying a depth of cutting is received, and a portion of a boundary surface within the specified depth of cutting along the boundary surface from an outer edge of the boundary surface toward an inside is determined as a cutting surface, and the boundary surface being between the excision region and a non-excision region in the organ. The image representing the organ in such a manner that only a partial blood vessel region, which is present in a neighborhood region of the cutting surface in the blood vessel region of the organ, is visually recognizable is generated from the three-dimensional image.