This paper describes an approach to retrieving information from document images stored in a digital library by means of knowledge-based layout analysis and logical structure derivation techniques. Queries on document image content are categorized in terms of the type of information that is desired, and are parsed to determine the type of document from which information is desired, the syntactic level of the information desired, and the level of analysis required to extract the information. Using these clauses in the query, a set of salient documents are retrieved, layout analysis and logical structure derivation are performed on the retrieved documents, and the documents are then analyzed in detail to extract the relevant logical components. A 'document browser' application, being developed based on this approach, allows a user to interactively specify queries on the documents in the digital library using a graphical user interface, provides feedback about the candidate documents at each stage of the retrieval process, and allows refinements of the query based on the intermediate results of the search. Results of a query are displayed either as an image or as formatted text.