An image display system comprises a display unit which includes regularly arranged red, green and blue pixel elements and which changes a displaying state of the pixel elements to display an image; a pixel data generator which generates pixel data consisting of three items of first pixel element data corresponding to red, green and blue signal levels; a pixel element data generator which converts the pixel data into several items of second pixel element data as a minimum unit data corresponding to the signal levels of respective colors; and a controller which selects any one of a first display mode on the basis of the pixel data outputted from the pixel data generator and a second display mode on the basis of the second pixel element data generated in the pixel element data generator, wherein when selecting the second display mode, the controller sets a pixel number of the pixel data generated in the pixel data generator so as to coincide with a display pixel number of the display unit.