A method for controlling a digital device, and which includes receiving content; displaying the received content on a display screen of the digital device; calculating, via a controller of the digital device, an average luminance value respective to an entire display screen where the received content is displayed; generating, via the controller, a histogram respective to a partial area of the entire display screen; analyzing, via the controller, the histogram respective to the partial area and verifying whether or not a pixel distribution ratio of pixels having a minimum gray level, among pixels being located in the partial area of the display screen, is equal to or greater than a reference ratio; and if the pixel distribution ratio of pixels having the minimum gray level is equal to or greater than the reference ratio, processing a luminance of the partial area of the display screen to be black.