pdf dblp CERTH's Participation at the Photo Annotation Task of ImageCLEF 2012 Eleni Mantziou | Georgios Petkos | Symeon Papadopoulos | Christos Sagonas | Yiannis Kompatsiaris CLEF 2012 Evaluation Labs and Workshop, Online Working Notes, Rome, Italy, September 17-20, 2012