1. A medical imaging apparatus comprising: a cardiac lumen region identifying unit configured to identify a cardiac lumen region from a medical image including a heart region; a myocardium identifying unit configured to identify a face of a myocardium region obtained by extending a face of the cardiac lumen region, identified by the cardiac lumen region identifying unit, by a certain distance at a time toward a myocardium side; and a generating unit configured to generate a color-coded image in which the face of the myocardium region, identified by the myocardium identifying unit, is colored in colors according to signal values of the medical image corresponding to positions on the face of the myocardium region.