1. A display device, comprising a display panel in which data lines intersect scan lines and pixels are arranged in a matrix form; an image rendering device for calculating saturation of each piece of pixel data of an input image, adjusting a sub-pixel rendering application ratio and a direct rendering application ratio for the pixel data using a weight in proportion to the saturation and converting the pixel data; and a display panel driving circuit for writing data converted by the image rendering device to the pixels of the display panel, wherein sub-pixel rendering adjusts values of input image pixel data related to a pixel according to an area ratio of the pixel, sums the pixel data values and converts the pixel data into data to be written to the pixel, wherein direct rendering selects pixel data having a center point closest to the center point of the pixel from among the pixel data and converts the selected pixel data into data to be written to the pixel, wherein the direct rendering application ratio is decreased by a sub-pixel rendering application ratio increase, and the sub-pixel rendering application ratio is reduced by a direct rendering application ratio increase.