1. A motion detection system comprising a processor, the processor implementing: a pixel-based detector that compares a previous frame and a present frame to extract pixels constituting a first foreground region; a region-based detector that determines a peripheral region centering around a pixel to be inspected, obtains a peripheral upper limit luminance and a peripheral lower limit luminance in accordance with a maximum luminance and a minimum luminance in the peripheral region, and extracts a second foreground region based on comparison of a luminance of the pixel to be inspected to the peripheral upper limit luminance and the peripheral lower limit luminance; and a motion determiner that detects a final motion region that comprises pixels belonging to both the first foreground region and the second foreground region, wherein the region-based detector extracts the second foreground region independently from an extracting of the pixel-based detector before the motion determiner detects the final motion region, wherein the first foreground region comprises a plurality of pixel groups, and the final motion region comprises pixels included in one of the plurality of pixel groups of the first foreground region, the one of the plurality of pixel groups of the first foreground region overlapping with the second foreground region, wherein the pixel-based detector comprises: a first foreground detector that detects the first foreground region by using a background difference image technique; and a labeler that groups pixels which are adjacent to each other among the pixels constituting the first foreground region into a plurality of pixel groups and assign an identification number to each of the plurality of pixel group.