1. A method of acquiring a green (G) channel value in a pixel having a red (R) channel value or a blue (B) channel value in a video display apparatus displaying a video input using a plurality of pixels, each pixel having one channel value among three channel values of R, G, and B colors, the method comprising: calculating first correlation similarity based on a difference between channel values of pixels positioned in a vertical direction, and second correlation similarity based on a difference between channel values of pixels positioned in a horizontal direction; and if a difference between the first correlation similarity and the second correlation similarity is not less than a threshold value, acquiring the G channel value from channel values of the pixels positioned in one of the horizontal direction and the vertical direction.