Designing local dimming algorithm for high contrast ratio and low power consumption for led backlight LCD TV sets

Backlight level of LCD TV with LED backlight unit can be dimmed locally depending on the input video. This feature saves power and increases contrast ratio. Dimming is applied by three ways; zero-dimensional dimming, one-dimensional dimming and two-dimensional dimming. Most popular and effective dimming type is two-dimensional dimming. There are many algorithms to achieve two-dimensional dimming and this thesis brings a novel approach to this issue. The algorithm developed at this study is realized on FPGA chipset and is applied successfully. Algorithm is implemented on 42? full high definition with LED backlight panels and TV sets which have full high definition output. Application uses low voltage differential signalling of TV mainboards and never manipulates image data.To see the results of the algorithm, three different measurements are taken from the system. Power consumption and contrast ratio are measured for five different images on cold cathode fluorescent lamp backlight, LED backlight and LED backlight with local dimming panels. Measured values have revealed that the algorithm is applied successfully. In terms of contrast ratio, improvement is very high on black-weighted images than white-weighted images. Measurements have emerged that power consumption depends on the white level of the image. It is approved that LED backlight panels, with local dimming or not, are better than cold cathode fluorescent lamp backlight panels in terms of both power consumption and contrast ratio.