1. A display device comprising: a display panel on which data lines and gate lines are positioned; a data driving circuit configured to drive the data lines; a scan driving circuit configured to drive the gate lines; a timing controller configured to control the data driving circuit and the scan driving circuit; and a data modulation circuit including a local modulation circuit and a global modulation circuit, the local modulation circuit being configured to map luminance components of input digital video data to a luminance transfer curve for each pixel based on an average picture level (APL) of each pixel and perform a first modulation on the luminance components of the input digital video data so as to expand a gray level distribution of a specific portion of an input image, the global modulation circuit being configured to perform a second modulation on first modulated luminance components of the input digital video data so as to improve an entire contrast characteristic of the input image and supply second modulated luminance components of the input digital video data to the timing controller.