1. An apparatus for extracting a single peak image, the apparatus comprising: an image selector, implemented by a processor or computer, configured to select one image from a sequence of continuously photographed images; a base image determiner, implemented by a processor or computer, configured to determine at least one base image according to a predetermined criterion; a difference calculator, implemented by a processor or computer, configured to calculate a difference between each selected image and only the at least one base image; and a peak image determiner, implemented by a processor or computer, configured to determine a single peak image among all the continuously photographed images of the sequence based on the calculated differences for all the selected images.