A device which includes a display can provide adjustable light output, based in part on the color of the display screen output, to control the light output of the display screen. An illumination processor can adjustably control light output based on the colors of portions of the display screen. The light output can be adjusted to maintain the light output of the display screen across a range of colors of display screen light output. Controlling the light output of the display screen results in controlling the illuminance of a subject. The device can include a camera which captures an image of the subject and displays the image on a portion of the display screen, where the light output of a portion of the display screen can illuminate the subject such that the captured image has at least a certain level of image quality.