. .

Inhalt

Making hypertext based study material accessible and user friendly to blind students

Author: Dr. Thomas Kahlisch

Abstract

This paper explains the services provided and the current projects at the Dresden University of Technology. The primary goal of the projects is to make study material accessible over the World Wide Web to blind and partially sighted students by using structured hypertext based document formats, like SGML. The paper describes the material preparation processes and the strategies used to improve access by blind students.

We also describe a Web service that transforms validated HTML documents into American, French, and German Braille.

The final part of the presentation describes a project to design and implement a hypertext Script Reader for SGML based documents, running on the graphical user interface Windows. This program will allow a blind user to read documents that follow a particular guideline to design accessible study material, on the WWW.

Development and improvement of designing methods for accessible and user friendly information systems is the main challenge of this work.
Table of contents

1. Introduction
2. Improving access to study material

2.1 Preparation of accessible study material
2.2 Transformation of ASCII documents into HTML

3. Transformation of HTML documents into Braille
4. Hypertext reader for SGML based study material

4.1 Script Reader
4.2 Table Browser

4.2.1 General principles
4.2.2 Provided functions

5. Conclusion

1 Introduction

This paper explains the services provided and the current projects at the Dresden University of Technology. The primary goal of our projects is to make study material accessible to blind and partially sighted students by using structured hypertext based document formats, like SGML [1].

The advantage of using SGML based document formats to improve the quality of electronically available reading material for print disabled persons is described in reports about the EU projects HARMONY [2] and MATHS [3] and in our report "A Journal Header Reader for the blind", [4] presented at the SGML Europe conference in May 1995.

The most common SGML DTD is HTML, used in the WWW. This document format provides structured markup which allows us to represent text based study material in an accessible format to blind users.

2 Improving access to study material

2.1 Preparation of accessible study material

Usually accessible study material at the Dresden University of Technology is provided in flat ASCII format. Information about the structure of the document, tables, mathematic expressions, graphics and pictures are represented in a textual format, according to particular guideline developed at the German Universities Dresden and Karlsruhe. The guideline (Tutorenanleitung - zur Umsetzung sehgeschädigtengerechter Studienmaterialien) [5] describes the following rules:

  • the general structure of an accessible document

  • how to set up tables in textual form

  • how to capture and describe graphic information and pictures

Mathematical expressions are specified in a particular notation called AMS (ASCII Mathematik Schrift) [6], which uses a programming language like syntax of ASCII characters to linearize equations.

Example AMS01 (A fraction): y = (x**2 + 3x -4)/(x-1)
Example AMS02 (An integral): y = Int[0;z] e**x dx


Blind and partially sighted students in Dresden do have access to the documents by using PC's with adaptive technology (Braille display, screen magnifier and speech synthesizer) in a local area network. The file service which stores these documents is called ELVIS (Elektronisches Literaturverzeichnis und Informationssystem für Sehgeschädigte) [7].

The provided study material in ASCII Format is less structured, which makes searching and linking for particular data difficult for the user. Our group decided to look for opportunities to improve access to the documents by using a platform independent structured hypertext system, like the WWW.

2.2 Transformation of ASCII documents into HTML

To make study material accessible over the Web, we developed a transformation service for ASCII text documents into the HTML format. The transformation is implemented as a batch process on a UNIX platform. The process is designed into two steps.

The first step converts the ASCII files into a format according to the ICADD22 DTD [8]. This DTD provides a basic set of SGML elements necessary to markup a document structure which is accessible to print disabled persons. This particular set of markup, designed by the ICADD (International Committee for Accessible Document Design), provides easy access to the general document structure in translating the data into different formats e.g. Braille, large print and computer voice.
The second step converts the ICADD files into the HTML V. 2.0 format.
In the current version of the service, tables are represented as plain text without using the particular HTML markup.
Mathematical expressions, which are given in the AMS notation, are not changed during the conversion process. This kind of data remains in the format and can be read by using text oriented WWW browsers.
To extend the service with the capability of translating tables and mathematical expressions into the appropriate HTML markup, it is necessary to improve our designing guideline for the ASCII documents. A new approach of this guideline is available in German at:
URL: http://elvis.inf.tu-dresden.de/~kahlisch/rl_v01/
Note, there is an English document available "Guidelines for the preparation of text materials on computer disk for people with print disabilities" [9], it describes a similar approach to provide structure information into ASCII documents.
The new guideline uses a number of tags, similar to the HTML markup, to represent more structure in the documents. This will allow us to rewrite and to improve the transformation process.

3 Transformation of HTML documents into Braille

To provide better access to the WWW, for persons who can read Braille, we developed a form based transformation service for HTML documents into American, French and German Braille. This service is designed by using the ICADD guidelines for the transformation of SGML documents into accessible formats for print disabled persons, published in Appendix 8 of the standard ISO 12083 [10].

The TU Dresden "International HTML to Braille Service" extends Jeff Suttors [11] idea of translating HTML files into American Braille, from one - into three languages. The transformation of the documents into the different Braille notations is designed by the use of the German HBS software [10].

The TU Dresden "International HTML to Braille Service" extends Jeff Suttors [11] idea of translating HTML files into American Braille, from one - into three languages. The transformation of the documents into the different Braille notations is designed by the use of the German HBS software [12]. The service is available at:

URL: http://elvis.inf.tu-dresden.de/html2braille/

The following Braille formats are available:

  • German contracted Braille

  • German uncontracted Braille

  • French uncontracted Braille

  • American uncontracted Braille


After filling out and submitting the form, the specified document will be translated automatically into the chosen Braille format and displayed by the browser. The user can read the result with a Braille display, store the information on disk or print it with a Braille printer.

A paper, presented at the international conference ICCHP [13], explains in more detail the implementation of the service and how it can be used.

4 Hypertext reader for SGML based study material

Our current project "Präsentation von elektronischen Dokumenten für blinde Menschen" [14] is due to establish access to hypertext based study material for blind students. By developing a SGML based Script Reader, we would like to make our prepared study material more accessible by using the WWW.

4.1 Script Reader

The Script Reader will run on MS-Windows 3.X and will be implemented by use of a particular SGML browser engine ViewPort [15]. This software, developed by the Swedish company SYNEX, is used in the SGML browser PANORAMA [16] from Softquad Inc.

The Script Reader will provide the following features:

  • Access to structured documents over the network

  • Hypertext navigation

  • Presentation of mathematical expressions in the AMS notation

  • Rendering of HTML tables into textual format

The use of the SGML browser engine will only allow us to make study material accessible, which is validated SGML, according to the HTML DTD. Currently we work with the HTML V. 2.0 and the table DTD. These DTD's provide, except for the math markup, all needed capabilities to describe the study material. The SGML functionality in the Script Reader will allow us to change this in further versions.

By using bridge software (Windows screen reader) to make the graphic user interface accessible to the blind user, the Script Reader will offer the following functions in separate windows:

  • Document viewing

  • Table of contents

  • Tables rendering

  • History

  • Bookmarks

The window, which is activated, will use the full screen to display the information. By highlighting hypertext links, the user can trace and navigate through the given structure of a document.

The system will not provide functions to edit or manipulate the documents but the user can extract and save information in private note - or bookmark files. The history function can be used to trace particular information and to memorize document ancestries.

4.2 Table browser

4.2.1 General principles

HTML Tables will be treated from the Script Reader in a separate window by using a particular table browser. The concept for the navigation and presentation of table information was developed by a student of computer science as part of his master's degree [17].

To test and evaluate the developed concepts, the first version of the table browser is implemented as a separate Windows 3.X application. It renders less and more complex structured HTML tables in different ways and displays the information in a way, which is accessible to blind users. A less structured and small table is displayed in a two dimensional way. Tables which are more complex are displayed using one line of the computer screen for each cell.

To support cooperative work of the blind user together with sighted people, the table browser additionally displays a small image of the general structure of the current table. This image can be found in a corner of the computer screen and does not disturb the blind user.

4.2.2 Provided functions

The current version of the separate table browser provides general functions over a pull-down-menu. The following table shows the items of the main menu and their general functionality:

item  
general functionality
FILE open, close or store a table
SEARCH search for content in a cell, repeat search
NAVIGATION table - and cell navigation functions
STATISTIC
shows the complexity and the number of rows,
columns and cells in a table
WINDOWS grouping and appearance of windows
HELP information on how to use the program

Table TAB01: (Items of the table browser main menu)

After a blind user has chosen a table he would like to read, by using the FILE menu, the SEARCH and the NAVIGATION menus become accessible in the main menu item list. The Cursor is located on the title of the table.
To get an overview of the displayed table, the user can activate the STATISTIC menu. The STATISTIC window contains information about the complexity of the table and the nubmer of rows, columns and cells in the current table. The complexity is a value between 0 (no complexity) and 1 (highest complexity). It tells the user, whether there are multiple lines in table cells or not.
Note, complexity is calculated as a quotient of vc (virtual cells) divided by vc plus rc (real cell). The vc is the sum of all COLSPAN and ROWSPAN attribute values in one table. The rc is the number of all cell elements in the current table.
To search for particular content in a table, the user can open the SEARCH menu.
By chosing items from the NAVIGATION menu, the cursor is located to the requested position in the table. Most items in this menu are also available as hotkeys. The following navigation functions are available:

Table TAB02: (Functions available to navigate into a table)

Menu item Description Hotkey
HORIZONTAL HEADER CELL cursor to the left header cell
in a row
CTRL+H
VERTICAL HEADER CELL cursor to the top header cell
in a column
CTRL+V
RIGHT CELL cursor to the right cell CTRL+CURSOR-RIGHT
LEFT CELL cursor to the left cell CTRL+CURSOR-LEFT
UPPER CELL cursor to the upper cell CTRL+CURSOR-UP
LOWER CELL cursor to a lower cell 
CTRL+CURSOR-DOWN
GO TO A CELL cursor to a requested position
(row, column)
CTRL+G
CURRENT CELL
cursor to the beginning of the
current cell
CTRL+C
TO FOOT cursor to the foot 
CTRL+F
GO BACK reverse the last navigation
CTRL+B


The listed control-key-functions allow the user to navigate from cell to cell in the structure of a table. The regular cursor keys can be used to move the cursor only in a cell.
These two levels of navigation (outside - and inside a cell navigation) help the blind user explore the structure and the content of a table.

5 Conclusion

At the end of our project, a new version of the table browser will be integrated in the first version of the Script Reader. It will have the capabilities of downloading files from the network and presenting tables which are included in HTML documents. In further projects it will be possible to extend the program with facilities to render HTML Math markup and tables in tables.

Any Feedback regarding this matter would be sincerely appreciated.
Author information

Author: Thomas Kahlisch
Address: Dresden University of Technology
Department of Computer Science
Institute of Information Systems
01062 Dresden
Germany

Bibliography

[1] ISO,ISO 8879:1986 Information Processing - Text and Office Systems - Standard Generalized Markup Language (SGML), Geneva, 15 October 1986.
[2] B. Bauwens, J. Engelen, F. Evenepoel, C. Tobin, T. Wesley: Structuring Documents: the Key to Increasing Access to Information for the Print Disabled in: 4th International Conference ICCHP '94, Proceedings, Vienna 1994.
[3] European maths project, URL: http://www.grif.fr/grifwork/tide.html
[4] Th. Kahlisch, Gunthild Vogel: A Journal Header Reader for the blind, SGML Europe'95 Conference, Gmunden 1995, URL: http://elvis.inf.tu-dresden.de/~kahlisch/europe.html
[5] TU Dresden, AG Studium für Blinde und Sehbehinderte, Universität Karlsruhe, Studienzentrum für Sehgeschädigte: Tutorenanleitung - zur Übertragung sehgeschädigtengerechter Studienmaterialien, 1995.
[6] TU Dresden, AG Studium für Blinde und Sehbehinderte, Universität Karlsruhe, Studienzentrum für Sehgeschädigte: ASCII-Mathematikschrift für Blinde, 1993.
[7] TU Dresden, AG Studium für Blinde und Sehbehinderte: ELVIS (Elektronisches Literaturverzeichnis und Informationssystem für Sehgeschädigte),
URL: http://elvis.inf.tu-dresden.de/
[8] ICADD, (International Committee for Accessible Document Design), Chair America: George Kerscher <kerscher@montana.com>Chair Europe: Tom Wesley <T.A.B.Wesley@bradford.ac.uk>
[9] Round Table on Reading Materials for People with Print Disabilities Inc.: Guidelines for the preparation of text materials on computer disk for people with print disabilities, V. 1.0, Sydney, July, 1995.
[10] ISO, ANSI / NISO / ISO 12083 Electronic Manuscript Preparation and Markup, Annex 8: Facilities for Braille, large print and computer voice, 1994.
[11] Jeff Suttor: HTML to ICADD Transformation Service, University of California - Los Angeles, URL: http://www.ucla.edu/ICADD/html2icadd-form.html
[12] HBS (Hagener Brailleschrift System), Fernuniversität Hagen - Gesamthochschule, Zentrum für Fernstudienentwicklung, Red. Fernstudium für Sehgeschädigte.
[13] Th. Kahlisch: Improving access to hypertext-based study material for the blind. In: Interdiscipliniary Aspects on Computers Helping People with Special Needs, Proceedings, Linz 1996, URL: http://elvis.inf.tu-dresden.de/~kahlisch/icchp.html
[14] TU Dresden, Lehrbereich Mensch-Maschine-Kommunikation ifS, Drittmittelprojekt: Präsentation von elektronischen Dokumenten für blinde Menschen,
URL: http://elvis.inf.tu-dresden.de/projekte/proj2.html
[15] SYNEX Inc.: ViewPort (SGML browser engine), URL: http://www.synex.se/
[16] SOFTQUAD Inc.: PANORAMA (SGML browser), URL: http://www.sq.com/
[17] A. Al-Kouni: Tabellen-Browser für Blinde, TU Dresden, Institut für Informationssysteme, Diplomarbeit Dezember 1996.