An emphasis converter 52 compares the image data of the current vertical period with the image data of the previous vertical period and controls the input image data to a liquid crystal display panel 4 based on the emphasis conversion parameters stored in tables of ROMs 3a to 3c so as to achieve accelerated drive. A microcomputer 38 is able to realize stable control of selecting emphasis conversion parameters by adding hysteresis to the detected temperature from a thermistor 37 even when the detected temperature fluctuates up and down crossing the temperature threshold.