A display device comprising: a display configured to output an image having a plurality of unit pixels; a brightness converter configured to acquire image data and to determine a brightness corrected image by correcting a brightness value corresponding to each unit pixel; and a controller configured to: detect whether a face is included in the image; determine a color corrected image based on whether the face is detected; and output the color corrected image or the brightness corrected image through the display based on whether the face is detected, wherein: when it is detected that a face is included in the image, multiply a color parameter of each unit pixel included in the brightness corrected image by a gain value so as to obtain the color corrected image and output the color corrected image through the display, when it is not detected that a face is included in the image, output the brightness corrected image through the display, characterized in that the controller is further configured to: extract a face detected region when the face is detected in the image; acquire the gain value corresponding to a size of the face detected region, wherein the gain value has a value between 0 and 1; wherein the gain value corresponding to the size of the face detected region is equal to a first gain value when the size of the face detected region is equal to a preset first value, is equal to a second gain value when the size of the face detected region is equal to a preset second value, and is equal to a third gain value when the size of the face detected region is equal to a preset third value, wherein the preset first value is smaller than the preset second value, the preset second value is smaller than the preset third value, the first gain value is greater than the second gain value, and the second gain value is greater than the third gain value, and wherein a slope from the first gain value to the second gain value is greater than a slope from the second gain value to the third gain value. a display configured to output an image having a plurality of unit pixels; a brightness converter configured to acquire image data and to determine a brightness corrected image by correcting a brightness value corresponding to each unit pixel; and a controller configured to: detect whether a face is included in the image; determine a color corrected image based on whether the face is detected; and output the color corrected image or the brightness corrected image through the display based on whether the face is detected, detect whether a face is included in the image; determine a color corrected image based on whether the face is detected; and output the color corrected image or the brightness corrected image through the display based on whether the face is detected, wherein: when it is detected that a face is included in the image, multiply a color parameter of each unit pixel included in the brightness corrected image by a gain value so as to obtain the color corrected image and output the color corrected image through the display, when it is not detected that a face is included in the image, output the brightness corrected image through the display, when it is detected that a face is included in the image, multiply a color parameter of each unit pixel included in the brightness corrected image by a gain value so as to obtain the color corrected image and output the color corrected image through the display, when it is not detected that a face is included in the image, output the brightness corrected image through the display, characterized in that the controller is further configured to: extract a face detected region when the face is detected in the image; acquire the gain value corresponding to a size of the face detected region, wherein the gain value has a value between 0 and 1; wherein the gain value corresponding to the size of the face detected region is equal to a first gain value when the size of the face detected region is equal to a preset first value, is equal to a second gain value when the size of the face detected region is equal to a preset second value, and is equal to a third gain value when the size of the face detected region is equal to a preset third value, wherein the preset first value is smaller than the preset second value, the preset second value is smaller than the preset third value, the first gain value is greater than the second gain value, and the second gain value is greater than the third gain value, and wherein a slope from the first gain value to the second gain value is greater than a slope from the second gain value to the third gain value. extract a face detected region when the face is detected in the image; acquire the gain value corresponding to a size of the face detected region, wherein the gain value has a value between 0 and 1; wherein the gain value corresponding to the size of the face detected region is equal to a first gain value when the size of the face detected region is equal to a preset first value, is equal to a second gain value when the size of the face detected region is equal to a preset second value, and is equal to a third gain value when the size of the face detected region is equal to a preset third value, wherein the preset first value is smaller than the preset second value, the preset second value is smaller than the preset third value, the first gain value is greater than the second gain value, and the second gain value is greater than the third gain value, and wherein a slope from the first gain value to the second gain value is greater than a slope from the second gain value to the third gain value.