1. A method of adjusting white balance, the method comprising: generating a display image by performing display image signal processing on an input image; outputting a representative color having a largest surface area of a selected area of the display image, the representative color output by a digital signal processor based on determining a color occupying the largest surface area of the selected area; simultaneously displaying at least two sample images corresponding to the selected area of the display image by applying different correction gains to the selected area of the display image that displays the output representative color, the at least two sample images being stored in a database; and applying the correction gain that is applied to a selected one of the at least two sample images to the input image.