Abstract: The problem of content-based retrieval of images from electronic media is especially acute in contexts where the subject-matter of the images is very general. The Birkbeck system attempts to overcome the limitations of traditional keyword systems, which provide a random and undifferentiated listing of objects in a picture, by using an augmented entity-relationship model in the data-modeling process. The interface, which allows successive query reformulation, emulates some of those aspects of browsing so important in picture collections. The subject-matter of the picture is described in terms of its objects, their attributes and the relationships existing between them. The form of the description (for both storage and retrieval) is defined by the grammar of the Picture Description Language and the Picture Query Language. Descriptions which are input to the system are parsed to generate SQL statements for the RDBMS which stores the data. Pictures relevant to the user's enquiry are retrieved and displayed in miniature for rapid consultation. To refine further the set of pictures selected the system allows query modification, which is supported by a thesaurus. Higher rates of recall and precision are achieved than are normally possible in image storage and retrieval. !3
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