An image processing apparatus, comprises an information acquiring unit that acquires three-dimensional data representing characteristic information on an object at a plurality of voxels; a shape information acquiring unit that acquires information on a surface shape of the object; a distance calculating unit that calculates, for each of the voxels, a distance between a surface of the object and a position inside the object corresponding to the voxel, based on the information on the surface shape; a filtering unit that performs, for each of the voxels, filtering processing, including blur processing in accordance with the calculated distance; and an image generating unit that generates a two-dimensional image, based on the three-dimensional data after the filtering processing.