In the QBIC (Query By Image Content) project we are studying methods to query large on-line image databases using the images' content as the basis of the queries. Examples of the content we use include color, texture, and shape of image objects and regions. Potential applications include medical ("Give me other images that contain a tumor with a texture like this one"), photo-journalism ("Give me images that have blue at the top and red at the bottom"), and many others in art, fashion, cataloging, retailing, and industry. We describe a set of novel features and similarity measures allowing query by color, texture, and shape of image object. We demonstrate the effectiveness of the QBIC system with normalized precision and recall experiments on test databases containing over 1000 images and 1000 objects populated from commercially available photo clip art images, and of images of airplane silhouettes. We also consider the efficient indexing of these features, specifically addre...

Multimedia information systems have emerged as an essential component of many application domains ranging from library information systems to entertainment technology. This is because these systems utilize a variety of human senses to provide an effective means of communicating information. However, most implementations of these systems (based on a workstation) cannot support a continuous display of high resolution audio and video data and suffer from fkequent disruptions and delays termed hiccups. This is due to the low U0 bandwidth of the current disk technology, the high bandwidth requirement of multimedia objects, and the large size of these objects which mquks them to be almost always disk resident. In this paper, we describe a parallel multimedia information system and the key technical ideas that enable it to support a real-time display of multimedii objects. These techniques are as follows. First, we decluster a multimedia object across several disk drives, enabling the system to utilize the aggregate bandwidth of multiple disks to retrieve an object in real-time. Second, the workload of an application is distributed evenly across the disk drives in order to maximize the processing capability of the system. To support simultaneous display of several multimedia objects for different users, we describe two altemative approaches. The first approach multitasks a disk drive among several requests while the second replicates the data and dedicates resources to each individual request. We investigate the trade-offs associated with each approach using a simulation model. Our results demonstrate the superiority of the replication approach.

The timeliness and synchronization requirement of multimedia data demands efficient buffer management and disk access schemes for multimedia database systems (MMDBS). The data rates involved are also very high and despite the development of efficient storage and retrieval strategies, disk I/O is likely to be a bottleneck, thereby limiting the number of concurrent sessions supported by a system. This calls for better use of data that has already been brought into the buffer by exploiting sharing whenever possible using advance knowledge of the multimedia stream to be accessed. This paper introduces the notion of continuous media caching which is a simple and novel technique where buffers that have been played back by a user are preserved in a controlled fashion for use by subsequent users requesting the same data. This is shown to have considerable impact on the performance of buffer management schemes. When continuous media sharing is used in conjunction with batching of user requests...

Distribution of continuous media traffic such as digital audio and video over packet-switching networks has become increasingly feasible due to a number of technology trends leading to powerful desktop computers and high-speed integrated services networks. Protocols supporting the transmission of continuous media are already available. In these protocols, transmission errors due to packet loss are generally not recovered. Instead existing protocol designs focus on preventive error control techniques that reduce the impact of losses by adding redundancy, e.g., forward error correction, or by preventing loss of important data, e.g., channel coding. The goal of this study is to show that retransmission of continuous media data often is, contrary to conventional wisdom, a viable option in most packet-switching networks. If timely retransmission can be performed with a high probability of success, a retransmission-based approach to error control is attractive because it imposes little overh...

The past decade has witnessed a proliferation of personal computers at homes, businesses, classrooms, libraries, etc. Most often, these systems are used to disseminate information. Recently, multimedia repositories have added to the excitement of this information age by allowing a user to retrieve and manipulate continuous media data types (audio and video objects). The design and implementation of these systems is challenging due to both the large size of objects that constitute this media type and their continuous bandwidth requirement. Compression in combination with the availability of fast CPUs (for real-time decompression) provide effective support for a continuous display of those objects with a high bandwidth requirement. Hierarchical storage structures (consisting of RAM, disk and tertiary storage devices) provide a cost-effective solution for the large size of their repositories. The focus of this study is on personal computers (single user, single display) that employ fast C...

In this paper, we propose a novel adaptive admission control algorithm, in which a client is admitted for service by a multimediaserver only if the extrapolation from the past measurements of the storage server performance characteristics indicate that the service requirements of all the clients can be met satisfactorily. Each client may request the retrieval of a variable bit rate (VBR) encoded media stream and may require a different quality of service. We also present a disk scheduling algorithm that minimizes both seek time and rotational latency incurred while accessing a sequence of media blocks from disk. We examine the effects of a finite read-ahead on the quality of service provided to each admitted client. The effectiveness of the admission control and disk scheduling algorithms is demonstrated through extensive simulations.

In this paper, we propose a novel adaptive admission control algorithm, in which a client is admitted for service by a multimedia server only if the extrapolation from the past measurements of the storage server performance characteristics indicate that the service requirements of all the clients can be met satisfactorily. Each client may request the retrieval of a variable bit rate (VBR) encoded media stream and may require a different quality of service. We also present a disk scheduling algorithm that minimizes both seek time and rotational latency incurred while accessing a sequence of media blocks from disk. We examine the effects of a finite read-ahead on the quality of service provided to each admitted client. The effectiveness of the admission control and disk scheduling algorithms is demonstrated through extensive simulations.

ion means the logical separation of the code of a groupware application into the functional core and the user interface part. Development of synchronous groupware is thought to benefit from abstraction. Users take on (sometimes several different) roles in groupware settings. Access rights are often dictated by the roles of the different users. Evidently, groupware tools should strive to aid programmers in tackling such complexities. We also found three surveys on groupware design issues [24, 51, 15] helpful when trying to get an impression of groupware developers' needs. Finally, some results from a closely related field: Researchers working on developing tools for singleuser user interfaces suggest that the following are desirable features of programming languages for implementing such systems [40]: ffl Efficient runtime execution. ffl Fast translation or compilation. ffl Portability to, and availability on, a wide range of platforms. ffl Facilities to support reuse. ffl Strong typ...

Distributed, networked multimedia information systems will be a critical component of technology-based information infra-structures in the future. Several ground breaking applications have already appeared, and many more are expected to follow. Innovations in hardware and software are feeding this revolution. In this paper, we present an infrastructure for multimedia applications. We discuss various characteristics of multimedia data and the effect of the network on required quality of presentation for multimedia data. The crux of the synchronization protocol is the scheduling of multimedia information for synchronized delivery, over broadband networks with limited resources, and is identified as an NP-hard problem. We introduce two parameters which can be used to measure the performance of endto -end synchronization protocol in a network supporting distributed multimedia applications. We propose and implement several heuristic scheduling algorithms for synchronized delivery of multime...

We make use of a refined E-R model to represent the contents of pictures. We propose remedies to handle mismatches which may arise due to differences in perception of picture contents. An iconic user interface for visual query construction is presented. A naive user can specify his/her intention without learning a query language. A function which computes the similarity between a picture and a user's description is provided. Pictures which are sufficiently close to the user description, as measured by the similarity function, are retrieved. We present the results of a user-friendliness experiment to evaluate the user interface as well as retrieval effectiveness. Encouraging retrieval results and valuable lessons are obtained. 1 Introduction With the advent of optical disk technology, multimedia computing systems [8] and data modelling techniques [12], it is becoming more and more feasible to maintain large information banks such as image databases. Such systems shall be able to suppor...