1. An image registration device, comprising: an artificial neural network in which a correlation between features is learned; a feature extractor configured to extract, using the artificial neural network, a first feature group from a first image and a second feature group from a second image; a feature converter configured to convert the extracted second feature group to correspond to the extracted first feature group to obtain a converted group; a register configured to register the first image and the second image based on the converted group and the extracted first feature group; and a learning device configured to perform an unsupervised learning on the artificial neural network.