1. An image processing apparatus, comprising: a selector to determine, from a plurality of sub-pixels included in a first pixel, which sub-pixels of the plurality of sub-pixels should receive an anti-aliasing process; and a processor to calculate a color value of the first pixel by performing the anti-aliasing process with respect to a selected sub-pixel of the first pixel having been determined to receive the anti-aliasing process, wherein the anti-aliasing process of the selected sub-pixel of the first pixel includes performing ray-tracing a plurality of times with respect to the selected sub-pixel based on the determining, wherein the selector determines which sub-pixels of the plurality of sub-pixels should receive the anti-aliasing process based on a comparison of the first pixel with surrounding pixels using an initial color value and a characteristic value of each of the first pixel and surrounding pixels, and wherein the characteristic value is a basic reference value used to determine whether each pixel is close to a boundary between objects, wherein the selector performs ray tracing with respect to the first pixel and neighboring pixels adjacent to the first pixel using a single ray, to calculate the initial color value and the characteristic value, and performs additional ray tracing on the plurality of sub-pixels, and wherein the additional ray tracing is performed a different number of times with respect to each of the plurality of sub-pixels.