1. An image processing apparatus, comprising: a computer comprising: a first selection unit to select a first pixel group including at least one pixel from an input color image; a second selection unit to select a second pixel group including at least one pixel, corresponding to each of the at least one pixel included in the first pixel group, from an input depth image, the input depth image comprising geometry information; a calculation unit to calculate a transformation function of the first pixel group and second pixel group based on a coordinate value of each of the at least one pixel included in the first pixel group and a coordinate value of each of the at least one pixel included in the second pixel group; and an image matching unit to match each pixel of the input color image with each pixel of the input depth image based on the transformation function, wherein the transformation function is a transformation matrix obtained by using a Direct Linear Transformation (DLT) algorithm.