With advancement of technology, end-users are stuffed with many kinds of portable handheld gadgets along with an enormous number of interactive multimedia communication and applications functionalities. These devices consume much power, especially for displaying their services or functions. In distinction, the battery, which is the main power supplier for such devices, has a much lower capacity growth compared to the power demands. This gap has motivated many researchers to study low-power display techniques. The invention of a light emitting diode (LED) in the meantime, as a new backlight source for a display panel. LEDs have been adopted in the most widely used Liquid Crystal Display (LCD) system. This paper compares noticeable low-power display techniques based on LCD systems, especially associated with an LED backlight unit as its light source. We classify these techniques namely into namely: a) low-power techniques with backlight dimming, b) low-power techniques with dynamic voltage scaling, c) software-based low-power techniques, and d) hardware-based low-power techniques, and review the core of each technique briefly. Out of many techniques used in a color sequential LED-backlit display concurrent brightness and contrast scaling technique achieved the largest power saving ratio by up to 90% of the total system power with a small distortion level.