1. A method performed by a medical image display apparatus, the method comprising: generating a three-dimensional (3D) stereoscopic image from volume data of an object, by an image generator of the medical image display apparatus, wherein the volume data of the object is acquired by a data acquisitor of the medical image display apparatus; generating at least one 2D stereoscopic image, by the image generator, based on at least one of a direction, a gradient, and a depth of a plane where a cross section of the object is located in the 3D stereoscopic image, wherein the at least one 2D stereoscopic image is parallel to or has a same depth as the plane; and displaying a medical image including the 3D stereoscopic image and the at least one 2D stereoscopic image in a stereoscopic imaging method, on a display screen of the medical image display apparatus, wherein the generating the 3D stereoscopic image comprises: performing a rendering of the volume data of the object at a point of view of one virtual camera of the medical image display apparatus; generating a plurality of images by dividing the rendered volume data of the object; and rendering a plurality of 3D stereoscopic images by setting the virtual camera in a virtual space where the object is located and changing a direction of ray casting towards the object from the virtual camera.