1. A marker processing method comprising: (a) binarizing an image including a marker to generate a binarized image; (b) labeling one or more constituents of the image based on the binarized image to generate labeled constituents; (c) obtaining a region centroid of each of the labeled constituents; (d) obtaining a degree of overlap of the region centroids of the labeled constituents; and (e) detecting the marker based on the degree of overlap of the region centroids, wherein the marker is detected if the degree of overlap of the region centroids is one of equal to and larger than 3.