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 a difference between channel values of pixels positioned in a vertical direction, and a difference between channel values of pixels positioned in a horizontal direction; and if the calculated difference between the channel values in the vertical direction and calculated difference between the channel values in the horizontal direction is not less than a threshold value, acquiring the G channel value from a channel value of the pixel positioned in one of the horizontal direction and the vertical direction.