@article {1909.09629, archivePrefix = {arXiv}, eprint = {1909.09629}, primaryClass = {eess.IV}, author = {Andreas Lugmayr and Martin Danelljan and Radu Timofte}, title = {Unsupervised Learning for Real-World Super-Resolution}, year = {2019}, url = {http://arxiv.org/abs/1909.09629} }