A display device comprising: an image processor ; a controller ; and a display ; an interface connecting the image processor and the display to each other; the image processor comprising: a first scaler configured to down-scale first contents at a first scaling magnification obtained based on a kind of the first contents, a resolution of the first contents and a power state of the display device , and a frame buffer configured to output the first contents down-scaled by the first scaler to the display through the interface ; wherein the controller is configured to determine a second scaling magnification based on the down-scaled first contents and an output resolution of the display device ; and wherein the display comprises a second scaler configured to obtain second contents by up-scaling, using an up-scaling scheme, the down-scaled first contents received from the frame buffer through the interface based on the second scaling magnification and is configured to display the second contents; wherein the second scaler is configured to determine an up-scaling scheme among a plurality of up-scaling schemes on the basis of the kind of the first contents, and wherein a first up-scaling scheme among the plurality of up-scaling schemes is determined in case the kind of the first contents is a text and a second up-scaling scheme among the plurality of up-scaling schemes is determined in case the kind of the first contents is an image including a natural scenery. an image processor ; a controller ; and a display ; an interface connecting the image processor and the display to each other; the image processor comprising: a first scaler configured to down-scale first contents at a first scaling magnification obtained based on a kind of the first contents, a resolution of the first contents and a power state of the display device , and a frame buffer configured to output the first contents down-scaled by the first scaler to the display through the interface ; a first scaler configured to down-scale first contents at a first scaling magnification obtained based on a kind of the first contents, a resolution of the first contents and a power state of the display device , and a frame buffer configured to output the first contents down-scaled by the first scaler to the display through the interface ; wherein the controller is configured to determine a second scaling magnification based on the down-scaled first contents and an output resolution of the display device ; and wherein the display comprises a second scaler configured to obtain second contents by up-scaling, using an up-scaling scheme, the down-scaled first contents received from the frame buffer through the interface based on the second scaling magnification and is configured to display the second contents; wherein the second scaler is configured to determine an up-scaling scheme among a plurality of up-scaling schemes on the basis of the kind of the first contents, and wherein a first up-scaling scheme among the plurality of up-scaling schemes is determined in case the kind of the first contents is a text and a second up-scaling scheme among the plurality of up-scaling schemes is determined in case the kind of the first contents is an image including a natural scenery. <EOS>