An authorization system for digital libraries

Digital Libraries (DLs) introduce several challenging requirements with respect to the formulation, specification, and enforcement of adequate data protection policies. Unlike conventional database environments, a DL environment typically is characterized by a dynamic subject population, often making accesses from remote locations, and by an extraordinarily large amount of multimedia information, stored in a variety of formats. Moreover, in a DL environment, access policies are often specified based on subject qualifications and characteristics, rather than subject identity. Traditional authorization models are not adequate to meet access control requirements of DLs. In this paper, we present a Digital Library Authorization System (DLAS). DLAS employs a content-based authorization model, called a Digital Library Authorization Model (DLAM) which was proposed in previous work [1]. Edited by Y. Yesha. Received: 21 December 2000 / Accepted: 6 March 2002 Published online: 14 May 2002     

Video OCR: indexing digital news libraries by recognition of superimposed captions

The automatic extraction and recognition of news captions and annotations can be of great help locating topics of interest in digital news video libraries. To achieve this goal, we present a technique, called Video OCR (Optical Character Reader), which detects, extracts, and reads text areas in digital video data. In this paper, we address problems, describe the method by which Video OCR operates, and suggest applications for its use in digital news archives. To solve two problems of character recognition for videos, low-resolution characters and extremely complex backgrounds, we apply an interpolation filter, multi-frame integration and character extraction filters. Character segmentation is performed by a recognition-based segmentation method, and intermediate character recognition results are used to improve the segmentation. We also include a method for locating text areas using text-like properties and the use of a language-based postprocessing technique to increase word recognition rates. The overall recognition results are satisfactory for use in news indexing. Performing Video OCR on news video and combining its results with other video understanding techniques will improve the overall understanding of the news video content.     

An algebra for creating and querying multimedia presentations

Over the last few years, there has been a tremendous increase in the number of interactive multimedia presentations prepared by different individuals and organizations. In this paper, we present an algebra for creating and querying interactive multimedia presentation databases. This algebra operates on trees whose branches reflect different possible playouts of a set of presentations. The algebra not only extends all the classical relational operators to such databases, but also introduces a variety of novel operators for combining multiple presentations. As our algebra supports merging parts or all of existing presentations, this algebra can also be used as an authoring tool for creating multimedia presentations. We prove a host of equivalence results for queries in this algebra, which may be used to build query optimizers for interactive presentation databases.     

An adaptive visual environment for digital libraries

CDL (Corporate Digital Library) is a prototypical intelligent digital library service that is currently being developed at the University of Bari, as an evolution of a previous project named IDL (Intelligent Digital Library). Among the characterizing features of CDL there are a retrieval engine and several facilities available for the library users. In this paper, we present the web-based visual environment we have developed with the aim of improving user-library interaction. The CDL environment is equipped with some novel visual tools that are primarily intended for inexperienced users, who represent most of the users that usually have access to digital libraries. Machine Learning techniques have been exploited in CDL for document analysis, classification, and understanding, as well as for building a user modeling module, which is the basic component for providing CDL with user interface adaptivity. This feature is also discussed in the paper. Received: 15 December 1997 / Revised: June 1999     

Browsing functions in three-dimensional space for digital libraries

In order to get useful information from various kinds of information sources, we first apply a searching process with query statements to retrieve candidate data objects (called a hunting process in this paper) and then apply a browsing process to check the properties of each object in detail by visualizing candidates. In traditional information retrieval systems, the hunting process determines the quality of the result, since there are only a few candidates left for the browsing process. In order to retrieve data from widely distributed digital libraries, the browsing process becomes very important, since the properties of data sources are not known in advance. After getting data from various information sources, a user checks the properties of data in detail using the browsing process. The result can be used to improve the hunting process or for selecting more appropriate visualization parameters. Visualization relationships among data are very important, but will become too time-consuming if the amount of data in the candidate set is large, for example, over one hundred objects. One of the important problems in handling information retrieval from a digital library is to create efficient and powerful visualization mechanisms for the browsing process. One promising way to solve the visualization problem is to map each candidate data object into a location in three-dimensional (3D) space using a proper distance definition. In this paper, we will introduce the functions and organization of a system having a browsing navigator to achieve an efficient browsing process in 3D information search space. This browsing navigator has the following major functions: ?1. Selection of features which determine the distance for visualization, in order to generate a uniform distribution of candidate data objects in the resulting space. ?2. Calculation of the location of the data objects in 2D space using the selected features. ?3. Construction of 3D browsing space by combining 2D spaces, in order to find the required data objects easily. ?4. Generation of the oblique views of 3D browsing space and data objects by reducing the overlap of data objects in order to make navigation easy for the user in 3D space. ?Examples of this browsing navigator applied to book data are shown. Received: 15 December 1997 / Revised: June 1999     

A hybrid approach for stereo disparity computation

An alternative, hybrid approach for disparity estimation, based on the phase difference technique, is presented. The proposed technique combines the robustness of the matching method with the sub-pixel accuracy of the phase difference approach. A matching between the phases of the left and right signals is introduced in order to allow the phase difference method to work in a reduced disparity range. In this framework, a new criterion to detect signal singularities is proposed. The presented test cases show that the performance of the proposed technique in terms of accuracy and density of the disparity estimates has greatly improved. Received: 24 June 1997 / Accepted: 15 September 1998     

User interaction in digital libraries: coping with diversity through adaptation

User interface adaptations can be used to address several user interaction challenges in the development of digital library systems. This paper: (a) examines some of the intrinsic characteristics of digital library systems; (b) identifies some of the key Human–Computer Interaction (HCI) challenges in relation to design and architectural abstraction for user interfaces to digital library systems; and (c) develops an argumentation for adaptations in digital library systems. By drawing parallels to recent HCI research into adaptable and adaptive user interaction, the paper illustrates potential areas in which user interface adaptation can provide a useful technique for advancing the quality of human interaction with a digital library system. Received: 18 December 1998 / Revised: 31 May 1999     

A scalable storage supporting multistream real-time data retrieval

This paper presents a new data placement scheme for continuous-media playback via a scalable storage system. Multimedia contents are segmented into data blocks for the purpose of being stored, retrieved, and manipulated. If these data blocks belong to some continuous media, then they must be handled in a timely manner, for example, being retrieved before some deadline. One of the main challenges in implementing the above system is the simultaneous retrieval of a great number of different media streams from a very large storage system. The proposed scheme efficiently reduces the seeking delay by a very simple placement method and a retrieval scheduler. Thus, both the storage capacity and the number of concurrent accesses to the storage are scalable. The performance of the proposed scheme is evaluated through a simple analytical model and a practical prototype implementation.     

A digital rights management scheme for broadcast video

Many watermarking techniques have been proposed for digital video and digital broadcast video. In general, they address the seller's or broadcaster's concerns, such as copyright-violation deterrence, copyright-violation detection and copy protection. Some of them provide for data integrity (tamper proofing), which is a shared concern of both subscriber and broadcaster. In all these cases, the watermark generation and embedding is performed or controlled by the seller or broadcaster. Therefore, a broadcaster with malicious intentions could, with manipulation, falsely implicate an innocent subscriber in copyright violation. This could be a major concern for subscribers. In this paper, we propose an integrated solution to manage the broadcaster's copyright and subscriber's false-implication concern (subscriber's rights) for digital video broadcasts. The proposed novel approach makes use of interactive watermarking techniques and protocols to help protect digital rights of all parties involved in video broadcasting.     

A framework for designing and implementing the user interface of a geographic digital library

Geographic data are useful for a large set of applications, such as urban planning and environmental control. These data are, however, very expensive to acquire and maintain. Moreover, their use is often restricted due to a lack of dissemination mechanisms. Digital libraries are a good approach for increasing data availability and therefore reducing costs, since they provide efficient storage and access to large volumes of data. One major drawback to this approach is that it creates the necessity of providing facilities for a large and heterogeneous community of users to search and interact with these geographic libraries. We present a solution to this problem, based on a framework that allows the design and construction of customizable user interfaces for applications based on Geographic Digital Libraries (GDL). This framework relies on two main concepts: a geographic user interface architecture and a geographic digital library model. Received: 15 December 1997 / Revised: June 1999     

TIME – a multi-leveled framework for evaluating and designing digital libraries

Even though these are early days for digital libraries, three decades of research on human-computer interaction in general, and the recent history of hypermedia research in particular, indicate that whatever else occurs, the usability of digital library applications will prove crucial to widespread acceptance. In the present paper an evaluation framework (termed TIME) is outlined. TIME offers designers and implementers of digital libraries a framework to address key human factors in a user-centered manner. Bridging all levels of human factors, from the ergonomic to the user goal, TIME is a multilevel framework that highlights the interplay of multiple issues affecting user response to digital documents. Received: 15 December 1997 / Revised: June 1999     

Integrating symbolic images into a multimedia database system using classification and abstraction approaches

Symbolic images are composed of a finite set of symbols that have a semantic meaning. Examples of symbolic images include maps (where the semantic meaning of the symbols is given in the legend), engineering drawings, and floor plans. Two approaches for supporting queries on symbolic-image databases that are based on image content are studied. The classification approach preprocesses all symbolic images and attaches a semantic classification and an associated certainty factor to each object that it finds in the image. The abstraction approach describes each object in the symbolic image by using a vector consisting of the values of some of its features (e.g., shape, genus, etc.). The approaches differ in the way in which responses to queries are computed. In the classification approach, images are retrieved on the basis of whether or not they contain objects that have the same classification as the objects in the query. On the other hand, in the abstraction approach, retrieval is on the basis of similarity of feature vector values of these objects. Methods of integrating these two approaches into a relational multimedia database management system so that symbolic images can be stored and retrieved based on their content are described. Schema definitions and indices that support query specifications involving spatial as well as contextual constraints are presented. Spatial constraints may be based on both locational information (e.g., distance) and relational information (e.g., north of). Different strategies for image retrieval for a number of typical queries using these approaches are described. Estimated costs are derived for these strategies. Results are reported of a comparative study of the two approaches in terms of image insertion time, storage space, retrieval accuracy, and retrieval time. Received June 12, 1998 / Accepted October 13, 1998     

A data model and a query languagefor multimedia documents databases

A multimedia application involves information that may be in a form of video, images, audio, text and graphics, need to be stored, retrieved and manipulated in large databases. In this paper, we propose an object-oriented database schema that supports multimedia documents and their temporal, spatial and logical structures. We present a document example and show how the schema can adress all the structures described. We also present a multimedia query specification language that can be used to describe a multimedia content portion to be retrieved from the database. The language provides means by which the user can specify the information on the media as well as the temoral and spatial relationships among these media.     

Zodiac: A history-based interactive video authoring system

Easy-to-use audio/video authoring tools play a crucial role in moving multimedia software from research curiosity to mainstream applications. However, research in multimedia authoring systems has rarely been documented in the literature. This paper describes the design and implementation of an interactive video authoring system called Zodiac, which employs an innovative edit history abstraction to support several unique editing features not found in existing commercial and research video editing systems. Zodiac provides users a conceptually clean and semantically powerful branching history model of edit operations to organize the authoring process, and to navigate among versions of authored documents. In addition, by analyzing the edit history, Zodiac is able to reliably detect a composed video stream's shot and scene boundaries, which facilitates interactive video browsing. Zodiac also features a video object annotation capability that allows users to associate annotations to moving objects in a video sequence. The annotations themselves could be text, image, audio, or video. Zodiac is built on top of MMFS, a file system specifically designed for interactive multimedia development environments, and implements an internal buffer manager that supports transparent lossless compression/decompression. Shot/scene detection, video object annotation, and buffer management all exploit the edit history information for performance optimization.     

A logical approach to multilevel security of probabilistic systems

Summary. We set out a modal logic for reasoning about multilevel security of probabilistic systems. This logic contains expressions for time, probability, and knowledge. Making use of the Halpern-Tuttle framework for reasoning about knowledge and probability, we give a semantics for our logic and prove it is sound. We give two syntactic definitions of perfect multilevel security and show that their semantic interpretations are equivalent to earlier, independently motivated characterizations. We also discuss the relation between these characterizations of security and between their usefulness in security analysis.     

Transformation and exchange of multimedia objects in distributed multimedia systems

One of the challenges in the design of a distributed multimedia system is devising suitable specification models for various schemas in different levels of the system. Another important research issue is the integration and synchronization of heterogeneous multimedia objects. In this paper, we present our models for multimedia schemas and transformation algorithms. They transform high-level multimedia objects into schemas that can be used to support the presentation and communication of the multimedia objects. A key module in the system is the Object Exchange Manager (OEM). In this paper, we present the design and implementation of the OEM module, and discuss in detail the interaction between the OEM and other modules in a distributed multimedia system.     

Usability study of digital libraries: ACM, IEEE-CS, NCSTRL, NDLTD

If digital libraries are to be used effectively, their user interfaces should be tested and enhanced. We observed 48 participants as they worked with the following digital libraries: ACM, IEEE-CS, NCSTRL, and NDLTD. We discuss how the features of these digital libraries influence the subjects’ efforts to perform search and retrieval tasks. Data analysis indicates that the IEEE-CS digital library was rated the best overall and NDLTD had the best search time. We present user recommendations and propose a taxonomy of features that we believe are essential for the design of future digital libraries. Noteworthy is the observation that users’ judgements on the importance of different features varied widely between the beginning and end of their test sessions. Received: 15 December 1997 / Revised: June 1999     

Non-linear dynamical system approach to behavior modeling

angular velocity control dynamic system guides the agent's direction angle, while another dynamic system selects the environmental input that will be used in the control system. The agent interacts with the environment through its knowledge of the position of stationary and moving objects. In our system agents automatically avoid stationary and moving obstacles to reach the desired target(s). This approach allows us to prove the stability conditions that result in a principled methodology for the computation of the system's dynamic parameters. We present a variety of real-time simulations that illustrate the power of our approach.     

OpenDLib: an infrastructure for new generation digital libraries

This paper presents OpenDLib, a digital library infrastructure that provides capabilities for new-generation digital libraries. In particular, the paper introduces a document model that can be used to represent a wide variety of document types and describes the open architectural infrastructure that allows for the expansion of the digital library through the dynamic plugin of new services.