MULTIGRADATION DISPLAY METHOD FOR IMAGE DISPLAY APPARATUS

PROBLEM TO BE SOLVED: To widely decrease a drive voltage by converting a binary data code of image to an optimum code considering the characteristic of image display and atmosphere of display system such as drive voltage condition and the like, and displaying graduation. SOLUTION: In an encoder 1 N bit binary code image data is inputted and the conversion into the M bit optimum code is carried out. With the optimum code an error diffusion theoritical part 2 forms a code subjected to M-n bit error diffusion process by applying error diffusion process to a lower n bit of M bit by use of the error bit information stored in an error buffer memory 3. The code is subjected to XOR logic process together with low function for selecting a scanning electrode, and synthesized into a digital data electrode drive signal with logical sum 6. The signal is converted into an analog signal by a D/A convertor 7 and outputted to a column drive unit 12 to drive the data electrode and also converted to a proper voltage and the data electrode of M×N liquid crystal display element 14 is driven according to the control signal.