High contrast ratio and low power consumption for LCDs with LED BLU can be obtained by backlight local dimming with pixel compensation while maintaining image brightness. This technique can greatly increase the contrast ratio of IPS-mode LCDs. The technique, however, suffers from the side effects called flicker, halo, clipping, and non-uniformity. The intensity of the side effects is proportional to the amount of the local dimming applied. This paper presents a noble local dimming algorithm which adaptively determines the amount of backlight dimming by characteristics of each block in each scene and feedback values to maximize contrast ratio and power consumption saving effect without noticeable side effects. The experimental results of the proposed algorithm are shown along with those of conventional algorithms.

A 2×2 module prototype is developed with four 15‐inch RGBW LCDs. Transmittance of LCD is increased with the low resolution, that is, qXGA(512×RG×384×BW). Using a new RGBW conversion algorithm, white and R/G/B luminance are increased 270% and 130% respectively in comparison with the 15‐inch conventional RGB LCD. An electronics system is implemented and a GUI is developed to support the hardware image control for tiled display.