“…Annotation-based image retrieval, on the other hand, enables users to formulate naturally semantic queries using textual keywords. In order to support this retrieval paradigm, many automatic image annotation techniques have been proposed, which assign a few relevant keywords to an unannotated image to describe its visual content for image indexing and retrieval (Feng, Manmatha, & Lavrenko, 2004;Guillaumin, Mensink, Verbeek, & Schmid, 2009;Jeon, Lavrenko, & Manmatha, 2003;Makadia, Pavlovic, & Kumar, 2008;Yanai, Shirahatti, Gabbur, & Barnard, 2005). The keywords are often derived from a well-annotated image collection and the number of keywords is often limited to a few hundred.…”