A backlight unit usable in an LCD for dynamically expanding color gamut of the LCD. In one embodiment, the backlight unit has a plurality of light emitting elements, and a control unit electrically coupled with the plurality of light emitting elements for controlling intensity of light emitting from each of the plurality of light emitting elements in response to a frame of image data applied to the plurality of pixels, wherein the control unit is configured such that when the frame of image data applied to the plurality of pixels is in a red color, a green color, or a blue color, the intensity of light from the red color, the green color, or the blue color emitting from each of the plurality of light emitting elements is adjusted to its corresponding maximal value so as to expand the red, the green, or the blue area of the color gamut of the LCD panel accordingly.