1. A method of enhancing a quality of a 3 dimensional (3D) image, the method comprising: classifying an input 3D image into a plurality of sub-areas based on noise characteristics of the plurality of sub-areas of the input 3D image; denoising each of the plurality of sub-areas of the input 3D image by using different denoising methods according to noise characteristics of each of the classified plurality of sub-areas and obtaining a second 3D image after the denoising; and enhancing a contrast ratio of the second 3D image after the denoising.