The increasing number of personal digital photos on the Web makes their management, retrieval and visualization a difficult task. To annotate these images using Semantic Web technologies is the emerging solution to decrease the lack of the description in photos files. However, existing tools performing manual annotation are time consuming for the users. In this context, this paper proposes a semi-automatic approach for annotating photos and photo collections combining OWL-DL ontologies and contextual metadata acquired by mobile devices. We also describe a mobile and Web-based system, called PhotoMap, that provides automatic annotation about the spatial, temporal and social contexts of a photo (i.e., where, when, and who). PhotoMap uses the Web Services and Semantic Web reasoning methods in order to infer information about the taken photos and to improve both browsing and retrieval.
