Paolo Bolettieri Andrea Esuli Fabrizio Falchi Claudio Lucchese Raffaele Perego Tommaso Piccioli Fausto Rabitti CoPhIR: a Test Collection for Content-Based Image Retrieval http://arxiv.org/abs/0905.4627 2009 CoRR abs/0905.4627 db/journals/corr/corr0905.html#abs-0905-4627 informal publication