The present invention relates to a method of controlling luminance of a backlight based on a processed image data after receiving information of image data, in order to improve the visibility of moving picture. An inverter according to the present invention includes a first block generating a first luminance control signal with an analog value depending on the luminance control signal with a duty ratio depending on a synchronization signal. The luminance control signals generated by the respective blocks are synthesized luminance control signal. Accordingly, a liquid crystal display employing two backlight control methods can be provided. Thus, it is possible to remove the drag phenomenon of a screen and, at the same time, to improve the visibility for moving picture.