WWW 94 Conference Paper: Networked Biomedical Image Hyperbase

Networked Biomedical Image Hyperbase

Authors

E. Duval, K. Hendrikx, H. Olivié
Computer Science Department, Katholieke Universiteit Leuven
Celestijnenlaan 200 A, B-3001 Leuven, Belgium
Tel: +32.16.20.10.15 (ext.3643); Fax: +32.16.20.53.08
Email: {Erik.Duval,Koen.Hendrikx,olivie}@cs.kuleuven.ac.be

P. O'Hanlon, D. Jameson
Audiovisual Centre, University College London
Windeyer Building, Cleveland Street, London W1P 6DB, UK
Tel: +44.71.636.8333 (ext.3056); Fax: +44.71.580.0995
Email: piers@livenet.ac.uk

J. Williams
Educational Technology Service, Bristol University
Royal Fort Annexe, Tyndall Avenue, Bristol BS8 1UJ, UK
Tel: +44.272.303500; Fax: +44.272.255985
Email: j.williams@bristol.ac.uk

Abstract

This paper presents a distributed hypermedia system, accessible through the World-Wide Web. The main components are an image store and a database. Our infrastructure is currently used in different educational scenarios.

In order to be able to carry out realistic field experiments, we have included the Bristol Biomedical Videodisc in the image store. This is a collection of ca. 20,000 high quality medical, veterinary and dental images.

We explain in some detail how WWW clients interact with the different components of our server. Some general points are made regarding the WWW approach and its applicability in a large-scale multimedia environment.

Partners

This paper presents some results of a collaborative research and development effort, involving three academic partners:

We started this collaboration in the context of the European projects CAPTIVE ('Collaborative Authoring, Production and Transmission of Interactive Video for Education', 1989-1991) and MTS ('Multimedia TeleSchools', 1992-1994) [Beckwith et al.93, Duval et al.94a, Duval et al.94b, Jameson et al.93]. Both projects were funded by the European Commission, in the framework of the DELTA ('Developing European Learning through Technological Advance') program.

Aim

Our aim is to develop an infrastructure for access to educational resources, enabling authors, developers, lecturers and students to locate and access material relevant to their needs. For this purpose, we have developed:

The material described in HyperDB can include traditional educational resources, like books, video and audio tapes, slides, etc. As this material cannot be made available on-line, the descriptive data stored in HyperDB indicate how it can be obtained (e.g. by sending an electronic mail request). If the relevant resources are stored on the image store, then they can be obtained through our infrastructure, as explained further on.

Typical Scenario

In a typical scenario, an end user first accesses HyperDB, in order to find out what material suits his needs. The role of HyperDB is similar to that of an OPAC (Online Public Access Catalog) in a traditional library. The underlying data model however is quite different:

Once the relevant resources have been identified, they can be accessed through a variety of means, depending on the type of resource and the infrastructure available at the receiving site. If the resource is a still image or a video sequence stored on the image store, then several options are available:

Case Study: Bristol Biomedical Videodisc

In order to be able to carry out realistic field experiments, we have included the Bristol Biomedical Videodisc in the image store. This is a collection of ca. 20,000 high quality medical, veterinary and dental images with an accompanying database. The data from that database have been incorporated into HyperDB.

Medicine, in general, is a highly visual subject and images form the basis of much of the teaching material. The Bristol Biomedical Videodisc was developed to meet the needs of teachers, particularly those creating computer-based teaching material, for an easily accessible archive of images.

The videodisc was created as a shared resource with the images having been donated by members of the leading medical, veterinary and dental institutions worldwide. Donors can therefore access not only their own images but a continually expanding collection of thousands more. It is distributed on a non- profit-making basis, with the intention of making it as widely available as possible to the general medical community.

A note on large-scale experiments: In the work we describe here, the videodisc essentially functions as a source of test material. We believe that is essential to have more of these experiments involving substantial amounts of data, in order to investigate wether and how the WWW can cope with these. The viability of the WWW approach for access to a relatively limited number of data per server (rarely more than ca. 50 files) has been proven by the enormous growth in popularity and the everyday extensive use of the web. However, servers with tens of thousands of images, as well as data describing the images, represent a different order of magnitude (see also next section).

Integrated Access through the World-Wide Web

The image store and HyperDB together constitute a distributed server. We rely heavily on the World- Wide Web for interaction with this server. For this purpose, we have set up WWW servers at each of the sites where a component of our server is located, in casu in London (U.K.) for the image store and in Leuven (Belgium) for HyperDB.

The following figure gives an overview of the different components and the communication protocols involved:

Forms stored on each of the WWW servers define the user interface for access to the corresponding component (Image Store or HyperDB). The functionality itself is implemented in separate software that is called when the form query is submitted, as explained in the sections about the Interaction between client and HyperDB and about the Interaction between client and image store.

The role of the WWW in this set-up is two-fold:

  1. The forms facilities of HTML allow us to use WWW software as a user interface management system: forms on our WWW servers define the kind of objects (e.g. a text input field, a menu, etc.) to be displayed to the end user. The WWW client will display these objects as appropriate in the context of the end user environment (e.g. with a motif look and feel under X-Windows).
  2. The HTTP protocol that defines interaction facilities for WWW clients and servers makes it possible to provide access to the WWW servers (and through them to the Image Store and HyperDB) from anywhere on the internet. This enables us to achieve our aim of providing access to educational resources for a potentially very large community of authors, developers, students and teachers.

It should be clear that none of the relevant data (apart from the forms) are stored in HTML files, as is mostly the case with more conventional WWW servers. When a form query is submitted to one of our WWW servers, a HTML document is generated at run time by the program that implements the functionality. It has been mentioned before (both on the Usenet newsgroup devoted to the WWW and in the www -talk mailing list) that this approach is more suited for more advanced applications.

We strongly believe that generating the HTML document to be delivered at run time is more appropriate in large-scale environments:

Interaction between Client and HyperDB

The Leuven WWW server holds a form that enables end users to specify search constraints involving characteristics of biomedical images (breed, sex, species, etc.). The purpose of the constraints is to identify relevant images that satisfy the requirements of the individual user. (You can try it out with userid='guest' and password='notneeded'!).

Some search constraints (on Species, Breed, etc.) can be selected in a scrollable list. Other comparison values must be typed in by the end user in a text field. Such a value can include search patterns:

The form enables end user to define search constraints, using a direct manipulation approach reminiscent of Query By Example [Shneiderman 92]. Comparisons involving two attributes describing the biomedical images are not supported (e.g. "Species > Description") as they do not make sense in this case. A more general query facility should support such comparisons as well.

When the form query is submitted to the Leuven WWW server (using the POST method), a program is executed through the Common Gateway Interface. This program translates the original request into a query for the HyperDB. As HyperDB runs under a Relational DataBase Management System (RDBMS), the database query is formulated in SQL and executed by the RDBMS.

HyperDB delivers data describing the images that satisfy the search constraints. The Leuven server thus effectively acts as a Hyperdocument library [Engelbart 90], that enables end users to locate relevant resources.

A similar form has been defined for query based access to data about organisations, persons, and journal articles. In fact, once the form query is submitted to the WWW server, the program that is called through the Common Gateway Interface (CGI), in order to process the query, is the same for these forms and for the form concerning the descriptive data about the biomedical images.

Interaction between Client and Image Store

The access to the LaserDisc is achieved through a CGI gateway. This has been written so as to provide digitised images on demand, thus providing quick access to a large image base. The real-time, on demand, digitising saves the use of large quantities of disk space. The gateway allows the user to specify the frame number on the disk (with possible exclusions due to copyright), in addition the size and type of the image can be specified thus offering the opportunity to provide both "thumbnail" images and full size images. This work has come from work in related areas[1,2,3].

A low level interface has been developed to the LaserDisc, which offers control of the device through it's serial port. The Sun Workstation connected to the LaserDisc player also contains a VideoPix frame grabbing card. When a request is made the frame number is verified as legal and a connection to the LaserDisc is established, which selects the appropriate image from the disc ( access time is under 0.5 second). The VideoPix card is enabled and the image grabbed, and according to the request the image is resized and converted to the desired type before transmission.

An interface to the image store has been developed which will allow individual access to the LaserDisc player, independently of the database program . This allows users to browse the disc.

Plans for the Future

We have a number of plans for the immediate future:

References