1. An apparatus configured to generate a medical image, the apparatus comprising: a sample image extractor configured to extract a sample image from an original image containing color information of an object; a color gamut modeler configured to model a color gamut of the sample image to have a predetermined shape; a 2D color map generator configured to generate a 2D color map based on the modeled color gamut; a volume data generator configured to generate 3D volume data based on a sectional image of inner tissues of the object; and a controller configured to generate a 3D color medical image by applying values of the 2D color map to a 3D grayscale medical image acquired by volume rendering of the 3D volume data.