1. A method of preparing an image signal for display, comprising: a computing device in an image source, which is separated from a display, defining an area of interest in an image, wherein the area of interest is less than the entire image; the computing device in the image source using gray level and brightness information pertaining to the area of interest to calculate and determine a control profile of the image, wherein the control profile of the image identifies a range of gray levels and a brightness for the area of interest; the computing device in the image source encodes the control profile of the image pertaining to the area of interest in metadata, the encoded control profile includes information for stretching the identified range of gray levels in the area of interest and illumination brightness adjustment information for the area of interest; and the computing device in the image source providing the encoded control profile in a video signal stream to simultaneously adjust backlight brightness and the range of gray levels of LCD pixels of the entire image in real time based on the encoded content of the control profile, wherein the control profile of the image is ignored by a display device not enabled to simultaneously adjust backlight brightness and adjust gray levels of the LCD pixels in real time based on the content of the image input.