High-DPI displays have a lower pixel aperture ratio than traditional displays, so the backlight needs to be brighter to give the same perceived brightness. Supp

High-DPI displays have a lower pixel aperture ratio than traditional displays, so the backlight needs to be brighter to give the same perceived brightness. Supposedly the new iPad retina display uses twice as many backlighting elements as the iPad 2. I don't believe switching is the major component in the display's power draw, since adjusting brightness has such a significant effect on battery life. If switching was the dominant factor, you would expect battery life to be roughly independent of brightness settings.