In an image matching apparatus of the present invention, only a connected region in which the number of pixels included therein exceeds a threshold value, among connected regions that are specified by a labeling process section, is sent to a centroid calculation process section from a threshold value processing section, and a centroid of the connected region is calculated. The intersection has a first lateral width, and the head tube above the intersection includes a tapered portion that tapers to a second lateral width narrower than the first lateral width. The invention further relates to radiation curable optical fiber coating compositions having a high dielectric constant.