A display driver includes a still image detector configured to receive a compressed image bitstream at an input frame frequency from a host processor, and to detect a still image by comparing the compressed image bitstream of a current frame and the compressed image bitstream of a previous frame, a driving frequency changer configured to output the compressed image bitstream at a first output frame frequency equal to the input frame frequency when the still image is not detected, and to output the compressed image bitstream at a second output frame frequency lower than the input frame frequency when the still image is detected, and a decoder configured to generate original image data at the first output frame frequency and the second output frame frequency.