1. A method for extracting a target, comprising: extracting a target region from an input image; extracting a background region from the input image by considering the size of the target region and a distance from the target region, wherein in extracting the background region, the background region is extracted by adjusting the size of the background region to be in inverse proportion to the distance from the target region; and extracting the target from the input image on the basis of the target region and the background region.