Output luminance of an RGB‐LED backlight for an LCD‐TV was adaptively dimmed along with input video signal in fashions of 0D (uniform dimming), 1D (line dimming), and 2D (local dimming). It has been proven experimentally that the backlight power can be reduced to 83%, 71%, and 50%, respectively, for a typical sample movie having 8.0% post‐gamma average picture level (which is equal to the average luminance level). Further simulation study revealed that the power consumption can be reduced to the value equal to that of the post‐gamma APL.

The luminance of a backlight unit for an LCD TV is adaptively and locally dimmed along with the input video signal in order to reduce the power consumption and also to improve the picture quality. By adopting the zero-dimensional (0D), 1D, and 2D adaptive dimming techniques, a sample movie having 8.0% post-gamma average picture levels (APL) could be displayed using 83%, 71%, and 50% of the original backlight power, respectively. For an adoption of the 2D dimming, an LED backlight is preferable. The adaptive-dimming technique also allows the differential aging characteristics between the LED components and temperature dependence of color and luminance to be overcome. From simulations of a reduction in power consumption, it was found that 40 × 40 pixels is a unit of the local dimming, 30 frames for the sampling period, 24 dimming steps, and an equalsignal-step method for determining the dimming factor have been found to be appropriate. The grayscale capability of low-luminance images can also be improved by dimming the backlight luminance and expanding the input signal. By using an LCD TV having an 8-bit capability, an 11-bit-equivalent gray-scale expression was experimentally proven.