A display screen comprises many pixel lamps arrayed uniformly and in a regular pattern. Pixel lamps come in three types (first- to third-color lamps), and image data to be displayed on the screen consist of bit-map type multi-colored data in which one pixel is represented by a set of three-type color data (first- to third-color data). Each color data plane on a bit-map image data plane is divided into many groups each consisting of a plurality of contiguous pixels, each group is correlated to each first color lamp on the display screen, an operation of selecting in a preset sequence first-color data of a plurality of pixels belonging to one group is repeated, and a first-color lamp correlating to each group is emission-driven according to a selected first-color data. (The same steps are followed for second- and third-color lamps).