An apparatus for displaying images. The apparatus comprises: an LCD panel comprising a plurality of pixels for displaying the images; and a backlight comprising a plurality of light sources. Each of the plurality of light sources is associated with one of a plurality of zones and each of the plurality of zones comprises a plurality of grid points. A controller coupled to the LCD panel and the backlight is configured to retrieve contour data associated with each of the plurality of light sources. The contour data is associated with a 3-D contour shape comprising a plurality of facets, each facet associated with at least one of the plurality of grids. The controller is configured to determine a brightness level of at least one pixel in a first grid based on a slope value associated with a first facet associated with the first grid.