A color compensation algorithm to avoid color distortion in active dimming liquid crystal displays

In LCD applications, various low power techniques, such as low voltage driving LEDs, high efficiency DC-DC converter circuitries, active backlight control schemes and the likes, have been applied to a backlight, which occupies the huge portion of total power consumption. Especially, it is a well-known fact that active dimming methods have accomplished considerable power reduction by as much as 20% up to 50% compared to the constant backlight method. However, the former technique may involve several artifacts such as color distortion, clipping, and so on. In this paper, color distortion in an active dimming LCD system caused by the mismatch between gamma values of pixel compensation algorithm and RGB sub-pixels, is analyzed and lowered by the proposed color compensation algorithm. This color compensation algorithm achieves the dramatic reduction on the color distortion without any loss of power saving performances. The maximum color difference ΔE_ab^max has been measured for each test image with the previous pixel compensation approaches (method-1 and method-2), and the average value of ΔE_ab^max has been obtained over 24 KODAK images. The resultant average value of a color compensated active dimming algorithm has been reduced to 0.413 and 0.478, compared to 24.595 and 9.527 of the conventional active dimming algorithms for method-1 and method-2, respectively.