1. A method of extracting a target, the method comprising: extracting a background image from an input image; modeling brightness values of the input image and the background image based on a Gaussian distribution to generate an input image modeling result and a background image modeling result; calculating likelihood ratios for determining whether a pixel in the input image corresponds to a target based on a correlation between the input image modeling result and the background image modeling result and target templates having different sizes; determining a location of the target based on the calculated likelihood ratios; and outputting the determined location of the target, wherein, for a plurality of targets, the determining of the locations of the targets comprises: receiving the likelihood ratios and a threshold for target determination; generating a target map having a same size as the input image, setting areas on the target map to have a first value when each of the likelihood ratios for the areas is greater than the threshold, and setting areas on the target map to have a second value when each of the likelihood ratios for the areas is not greater than the threshold; and determining each area set to the first value as a single target, setting a representative location for each of the plurality of targets, and determining the representative locations as locations of the plurality of targets.