Data annotations are an important kind of metadata that occur in the form of externally assigned descriptions of particular features in Web accessible documents. Such metadata are eventually used in data retrieval tasks on heterogeneous, possible distributed Web-accessible documents. In this paper, we present the model and realization of an annotation framework that scientists can employ to semantically enrich differerent types of documents, primarily scientific images made availabe through an

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... mage respository. Although we employ ontology like structures, called concepts, for metadata schemes used in annotations, our primary focus is on how concepts are actually used to annotate images and regions of interest, respectively, that exhibit features of interest to a researcher. It turns out that the combined consideration of domain specific concepts and annotated regions in images provides interesting means to analyze the usage of metadata regarding certain correctness and plausibility criteria. We detail our annotation management framework in the context of the Human Brain Project in which Neuroscientists record their observations on specific brain structures, and share and exchange information through concept-based annotations associated with images.