Modern computer networks make it possible to distribute documents quickly and economically by electronic means rather than by conventional paper means. However, the widespread adoption of electronic distribution of copyrighted material is currently impeded by the ease of unauthorized copying and dissemination. In this paper we propose techniques that discourage unauthorized distribution by embedding each document with a unique codeword. Our encoding techniques are indiscernible by readers, yet enable us to identify the sanctioned recipient of a document by examination of a recovered document. We propose three coding methods, describe one in detail, and present experimental results showing that our identification techniques are highly reliable, even after documents have been photocopied. I. INTRODUCTION E LECTRONIC distribution of publications is increasingly available through on-line text databases, CD-ROM's, computer network based retrieval services, and electronic libraries [1]--[...

Hypertext is an appealing interface for digital libraries, but using existing paper documents to build such a library poses several challenges. We describe a system for creating hypertext links on the fly in a library composed of bitmapped images of paper documents and text derived from those images by optical-character recognition. We present two simple ideas: text-image maps coordinate text and image representations of a document, and our probabilistic search heuristics generate hypertext links from the text of citations. Using the World-Wide Web, we built an interface that lets readers move from a bibliography entry to the cited document with a mouse click. Similarly, readers can click on entries in the table of contents and move directly to them. INTRODUCTION This paper describes an ongoing research effort to support the use of bitmapped images as the primary storage and presentation format of future digital libraries. Using images simplifies the task of creating computerized lib...

be delivered in electronic form. In addition, as libraries become increasingly more computerized, not just card catalogs but entire books will be stored on-line. When delivering digital documents from on-line libraries, two problems must be addressed; delivering a document which may be available in multiple formats and preserving relationships among the different formats. This thesis describes a system for delivering digital documents, called digiments, which can be in multiple arbitrary formats, while preserving the relationships between the parts and meta-data about the document itself.

Modern computer networks make it possible to distribute documents quickly and economically by elem"( * means rather tham by conventional paper means. However. the widespread adoption of electronic distribution of copyrighted muterial is currently impeded by the euse of illirit copying und dissemination, In this puper WO propose techniqu t>s hut discourage illicii distribution hv embedding each document with U unique codeword. Our encoding techniques are indiscernible by rruders. yei enable us to identifi th8e sanctioned recipient of U document by emminution qf a recovered docurneni. We propose three coding methods, describe one in drtail, und present experimental results showing that our identifieution techniques are highly reliable, ellen ufter docwments have been photocopied. 1.