In recent years, the low power technology has brought up a great impact on portable electronic devices. As for the mobile device, the low-power circuit design becomes the primary issue. At present, TFT LCD has been widely used in handheld mobile devices. In terms of the overall system power consumption, TFT LCD power consumes 20%~45% of the total system power depletion due to different applications. However, the most power consumption of TFT LCD is backlight dimming. Therefore, controlling the backlight current can reduce the overall power consumption. However, the drawback is that the reduction of brightness and contrast may cause significantly changes in visual experience. In order to reduce the power consumption and eliminate the changes of visions; how to reduce current, adjust brightness and contrast in accordance with the current image is worthy to investigate it.