The dataset contains 22 challenging pairs of images for image alignment.Related publications:Gehua Yang, Charles V. Stewart, Michal Sofka, and Chia-Ling Tsai, "Registration of Challenging Image Pairs: Initialization, Estimation, and Decision"IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 29, no. 11, pp. 1973-1989, Nov. 2007 (PDF)