1. A local contrast enhancement method performed in a video editing system, comprising: obtaining a first frame and a second frame in a video, wherein the first frame is designated as a reference frame and the second frame is designated as a current frame; partitioning the reference frame into a plurality of reference regions; determining a color distribution for at least one of the reference regions in the reference frame; deriving a first color mapping function for at least one of the reference regions in the reference frame according to the corresponding color distribution, wherein the first color mapping function comprises, for at least one of a predetermined set of colors, a first source color value and a first contrast-enhanced color value; partitioning the current frame into a plurality of regions; deriving a second color mapping function for at least one of the regions in the current frame according to the first color mapping functions of at least two of the reference regions in the reference frame; and applying the second color mapping function to the at least one of the regions in the current frame to generate a contrast-enhanced frame.