@Lightlyseared That is not my understanding of how a backlit LCD display works. Now an LED is a little light bulb, but LCDs produce no light of their own; they merely filter it.
What uses the most power is the backlight most often a cold-cathode fluorescent lamp. On some laptops, the backlight alone accounts for over 40% of the energy drawn by the system; often more than the CPU and wifi combined. The reason an iPod Touch can play over 30 hours of music but only six hours of video is the backlight, which is usually off for music but always on for video.
Most laptops use a Twisted Nematic (or TN) type TFT (Thin Film Transistor) LCD. With zero voltage applied, they allow light through. As applied voltage increases, they block more light.
As counter-intuitive as it may seem, the most efficient color is white! That is the natural color of a backlit LCD that has zero voltage applied to the pixels; any other color (especially black) requires voltage applied to the pixels to block the backlight’s illumination.
That said, you can get bigger gains by turning your backlight down and setting it to turn off after a short idle period.