Document analysis-from pixels to contents

The authors present a conceptual framework for solving the task of document analysis, which, in essence, consists in the conversion of the document´s pixel representation into an equivalent knowledge network representation holding the document´s content and layout. Starting on the pixel level, the formation of elementary geometric objects on which layout analysis as well as the definition of character objects is based is described. Character recognition accomplishes the mapping from geometric object to character meaning in ASCII representation. On the next level of abstraction words are formed and verified by contextual processing. Modeled knowledge about complete documents and about how their constituents are related to the application forms the highest level of abstraction. The various problems arising at each stage are discussed. The dependencies between the different levels are exemplified and technical solutions put forward