In this paper, a novel approach, which combines color transformation and dimming synergistically with respect to both power saving and image quality, is proposed for thin film transistor liquid crystal displays (TFT LCDs). This approach adaptively selects an allowable perceptual value that depends on the luminance value of an image (or frame) and dims the backlight based on it. The technique is implemented using an image viewer and a video playback program on an LED backlight unit-based TFT LCD board. Experimental results show that the proposed approach achieves on average 34.5% and 21.19% power savings for still images and video files, respectively, without affecting the visual quality of the images and with an overhead of 4.09% for video files.