Enhancement of Backlight-Scaled Images

Switching the liquid crystal display (LCD) backlight of a portable multimedia device to a low power level saves energy out results in poor image quality especially for the low-luminance mage areas. In this paper, we propose an image enhancement algorithm that overcomes such effects of dim LCD backlight by aking the human visual property into consideration. It boosts he luminance of image areas below the perceptual threshold while preserving the contrast of the other image areas. We apply he just noticeable difference theory and decompose an image nto an HVS response layer and a background luminance layer. The boosting and compression processes, which enhance the visibility of the low-luminance image areas, are carried out in the background luminance layer to avoid luminance gradient reversal and over-compensation. The contrast of the processed image s further enhanced by exploiting the Craik-O'Brein-Cornsweet visual illusion. Experimental results are provided to show the performance of the proposed algorithm.