1. A medical imaging apparatus comprising: a scanner configured to obtain projection data of an object; a three-dimensional restoring module configured to restore a volume of the object based on the projection data; a volume segmentation module configured to segment a plurality of material volumes corresponding to a plurality of materials included in the object based on the volume of the object; a reprojection module configured to generate a plurality of reprojection images according to the plurality of materials by reprojecting the plurality of material volumes from a plurality of virtual viewpoints; and an image fusion module configured to generate a plurality of fusion images according to the plurality of virtual viewpoints, each of the plurality of fusion images being generated by fusing reprojection images obtained from the same virtual viewpoint.