S-curve global dimming algorithm can reduce the power consumption of LED-lit Liquid Crystal Display (LCD) and improve the static contrast of display images.In order to further increase the power-saving efficiency,a two-step dynamic dimming algorithm based on S-curve is proposed.First,the gray levels of all sub-pixels of the input image are adjusted according to the maximum gray level,the pixel gray levels of input image are upgraded on the whole.Then,the pixel compensation is performed to the linearly amplified image with S-curve,and backlight brightness signals after adjustment are output at the same time.The simulation results of 40 typical images show that: the average backlight power is saved by 30%,and the static contrast is increased by 33%.The engineering prototype is developed to test six common TV programs.The result shows that the overall average power-saving is 25.1%,and the static contrast is increased by 30%.Compared with S-curve global dimming algorithm,the proposed algorithm can further increase the power-saving efficiency by 10% while maintaining the same display performance.