Making Graphics Accessible

Keywords: accessibility, universal access, blind users

Vladimir Bulatov, Ph.D.

ViewPlus Technologies


John A. Gardner, Ph.D.

ViewPlus Technologies



ViewPlus is expanding its current hardware/software product line to include a group of SVG (Scalable Vector Graphics) applications that make it possible for most kinds of SVG graphical information to be universally usable by all people including those who are blind or have other print disabilities. SVG permits graphical objects to have title and description attributes. The author of a well-structured object-oriented SVG file needs only to provide meaningful titles for important objects using the ViewPlus SVG Editor in order to make the information universally usable.

People with print disabilities can view the SVG file using the accessible SVG Reader that speaks the title attribute when the object is selected. People who are dyslexic or have several other print and/or cognitive disabilities can gain improved access to the information using a touch screen monitor, tablet PC, or other point and click mouse alternative. Blind users will create a tactile copy of the SVG display by printing to a ViewPlus tactile graphics and braille embosser and then place the copy on a point and click surface such as a ViewPlus touch pad. The embossed copy is a faithful rendition of the display, so the blind user can locate features and click to hear the titles. This combination of tactual and audio information is known to provide excellent access to graphical information by blind people.

Table of Contents

1. Introduction
2. SVG as a Language for Accessible Graphical Information
3. The Tiger Tactile Graphics Embossing Technology
4. Use of SVG by Blind People

1. Introduction

Information on a printed page cannot be read, or can be read only with difficulty, by people who are blind, dyslexic, or have other print and/or cognitive disabilities. However these people can read plain text on computers using software applications that read from the screen using a speech engine. Screen reader applications for blind people [Window-Eyes] , [JAWS] provide excellent access to plain text, permit keyboard navigation, and can display information either in speech or on an on-line braille display. Screen readers for sighted people with print disabilities [TextHelp] , [JAWS] , [Kurzweil] permit text to be selected and read aloud. Many screen readers highlight the sentence and/or word as it is being read to assist sighted users to keep up.

Unfortunately, access to plain text is not enough. Charts, diagrams, and graphs are common in business, scientific, and most professional literature. Maps and geographically-oriented data such as weather maps and complex census information would be virtually impossible to present in words. Until recently it has not been possible for authors of mainstream literature to present graphical information of these kinds in a format that could be accessed directly by people with severe print disabilities. In this paper, a SVG-based ( [SVG] [Eisenberg] [Jackson] ) technology is described that does permit people with print disabilities to have direct access to most object- oriented graphical information. This access is enabled by the ViewPlus Tiger ™ technology for embossing tactile graphics.

The SVG format permits graphical objects to have title and description attributes, and these attributes are used to ensure that SVG graphical information can be accessed by people with print disabilities who cannot easily understand the visual representation. These attributes are not visible when the SVG graphic file is displayed in a conventional SVG viewer but can be displayed and, if desired, spoken by users of the accessible ViewPlus SVG Reader application. The titles are displayed/spoken when selected with the mouse. Blind users can emboss a tactile copy of the SVG graphic, place it on a touch-sensitive pad, and select objects by pressing on the tactile copy. This technique of enhancing tactile information with additional audio was pioneered by Parkes ( [Parkes 1988] , [Parkes 1991] , [Parkes 1995] , [Parkes 1998] , [Parkes Brull 1997] ) and used extensively to provide graphical information to blind users ( [Loetzsch 1994] , [Loetzsch Roedig 1996] , [Landau 2003] ). Properly used the tactile plus audio information is known to provide excellent access to blind users. Bulatov and Gardner ( [Bulatov Gardner 1998] , [Gardner 2002] , [Gardner, Bulatov 1998] , [Gardner Bulatov 2001] , [Gardner Bulatov 2003] , [Gardner et al. 1997] ) have explored the feasibility of using mainstream graphics languages accessed by this tactile/audio method.

2. SVG as a Language for Accessible Graphical Information

SVG is a powerful language permitting animation and interactivity, but its most prevalent use is currently as a compact format for conveying static vector graphics on the web and in other electronic media. Its compactness and scalability are the major advantage of SVG over bit maps, currently the most common format for web and other electronic graphics. The inclusion of title and description attributes in the SVG specification along with other features promoting accessibility make SVG a nearly ideal language for creating accessible graphics. Accessibility is not automatic however. An author must include adequate titles for important graphic objects if an SVG file is to be accessible. Some chart or graph creation applications could include all titles and data so that the resulting SVG export could be automatically accessible. At the present time, SVG files can be made accessible only with a ViewPlus SVG file editing application scheduled for release in late 2004 as part of the new ViewPlus Chameleon Information Technology.

3. The Tiger Tactile Graphics Embossing Technology

Embossing Braille printers have been commercially available for more than two decades, and most current models can emboss "Braille graphics that typically have resolution of 10 dots per inch, but some models can achieve 16 dpi. The embossers receive data as strings of ASCII characters. Graphics are constructed with specialized DOS or Windows applications created especially for embossers. Until the commercial introduction of the Tiger technology by ViewPlus in 2000, the only other commercially-available technology for creating tactile graphics from computers was "capsule paper". This paper is treated with a chemical that swells at a certain temperature. Typically one prints or copies an image onto a piece of swell paper and runs it through an IR heater that causes the black areas to swell. Skilled workers can sometimes obtain variable height raised graphics by using grays, but these are not easily reproducible.

The Tiger embossing technology was developed within the Science Access Project [SAP] at Oregon State University ( [Sahyun et al. 1998a] , [Sahyun et al. 1998b] ) and subsequently expanded and commercialized by ViewPlus ( [Gardner 2002] , [Gardner et al. 2002] , [Walsh Gardner 2001] . Tiger technology is capable of embossing with a resolution of 20 dots per inch or equivalently 400 dots per square inch, and with variable height dots. The ViewPlus embossers utilizing this technology include the Pro (100 Braille characters per second, paper widths to 16 inches), the Max (60 Braille characters per second, paper width to 11.5 inches), the Cub (50 Braille characters per second, paper widths to 8.5 inches), and the Cub Jr. (30 Braille characters per second, paper width to 8.5 inches).

All ViewPlus embossers are accessed by Windows applications through the normal print command just as any Windows printer. Graphics are reproduced normally as height-resolved gray-scale images in which black areas produce high dots, and light gray areas low dots. Text and graphics can co-exist and be embossed. Braille text will be embossed as Braille whereas standard fonts, e.g. Arial, Times Roman, emboss as graphic images.

The variable dot height embossing capability and standard Windows printer interface for ViewPlus embossers permit a blind user to create a tactile copy of most graphic images whose major features are tactually identifiable. This is a critical necessity for blind users to have any chance to access mainstream graphics. Tactual accessibility can be optimized by users through a variety of user commands that presently or in the near future include ability to change contrast and brightness, to emboss outlines only, and to emboss colors as distinctive patterns.

4. Use of SVG by Blind People

The first commercial end-user products supporting the accessible SVG technology are a touch-sensitive pad and the accessible ViewPlus SVG Reader Windows software application scheduled for release by ViewPlus late in 2004. The SVG Reader is a free application downloadable from the web. It uses Batik [BATIK] toolkit for SVG display. The touch-sensitive pad attaches to the user's computer through a USB port and requires no other power. Once installed, the user needs to follow a very simple calibration step to assure that the image on the computer monitor corresponds exactly to the position of the corresponding tactile image on the touch-sensitive pad. The calibration needs to be done only once unless the page setup is changed to print with different margins or to a different paper size. The touch-sensitive pad is optimized for use with A4 or 8.5 x 11 paper. Once the touch-sensitive pad is installed, a blind user having access to a ViewPlus embosser needs only the accessible SVG file. The user opens the file in the SVG Reader, prints a copy on the Tiger embosser, and places the copy on the touch-sensitive pad. The user presses on an object and hears the computer speak the name of that object. For example, on a map showing all the countries of Europe, a user can press on a country and hear its name. If the author has included additional information about that country in the optional description field, the user can hear the description. If the user wants to review information, she can switch to a text window and browse anything that has been spoken. This capability makes it possible for authors to include wordy descriptions. All spoken information is also readable in Braille using any common Braille screen reader.

The map of Europe includes large and small countries. While it may be possible to distinguish Germany, France, Spain, Italy, and other large countries on a A4 or 8.5x11" embossed image, the Benelux countries, Monaco, Andorra, Liechtenstein, and other small countries are nearly impossible to distinguish tactually. Fine details even of large countries are also often not tactually distinguishable. Therefore a user will probably want to zoom the image to enlarge features of interest. There are a number of ways to do this. The SVG Reader permits one to zoom in or out and to pan left, right, up, or down. These are very useful for sighted users and are useful for fine adjustments by blind users. However the two most useful zoom features for blind users are the ability to select an object and zoom it to maximum size. For example, if a user is lucky enough to click on Luxembourg while browsing the full map, she can click on the "fit selection to window" item in the View menu. Alternatively a user may select the "zoom rectangle" menu item, then select two points that define the diagonally-opposite corners of a rectangle that will been zoom to maximum size permitted by the current window. One makes a copy of the zoomed image on the ViewPlus embosser, and then explores the zoomed image. One can always return to the full Europe map with the "fit to window" menu item.

When a user prints an image on the embosser, the computer saves the parameters of that image. If at a later time one wants to return to that particular image, one can place the tactile copy on the touch-sensitive pad, choose the "open from bar code" menu item, and touch a tactile "bar code" on the image to recall the correct file and zoom display to the screen. There are several alternative methods for providing the "bar code" information, eventually including a standard ink bar code. In some cases, users may need to read graphics files in locations remote from a ViewPlus embosser. In such a case the reader would need the SVG files and embossed copies of all files. If several zoom views are needed, the specially recorded zoom information recalled by the bar code would also be needed. These can be prepared by the user and taken to another remote computer or can be prepared by another person.

Few mainstream graphical documents are made without some text, a title, or labels on some objects, or as scale factors on graphs and bar/column charts. Typical text made for sighted people is far too small for a tactual image to be meaningful without being enlarged by a factor of three or more. Consequently, text in an embossed copy of a SVG graphic is usually not even possible to identify as text. Nonetheless, when a text object is pressed, the text is spoken, so a blind user can "read" titles and text labels on graphics. A user option permits one to replace the 20 dpi text images (that are little more than tactual noise) as special "text patterns" that are more readily identifiable. These text and graphics user options provide an experienced blind user with tools that can make almost any image in accessible SVG format usable.


Figure 1: Photograph of young blind woman examining a US map using the ViewPlus SVG Reader computer application and ViewPlus touch pad. The ViewPlus Cub Tiger tactile graphics and braille embosser is on her left. Any graphic on screen can be embossed on the Cub and placed on the touch pad.

These end-user products require that the SVG files be made accessible by providing titles for all important graphical objects. ViewPlus will market a SVG Creator software application that provides a user-friendly way to import SVG files, to convert almost any other file format to SVG, and to add object titles and descriptions. The editing process is very simple if the SVG file has well-defined objects. Most common authoring programs can provide well-structured SVG exports if an author is careful in defining the graphical objects. Such files can then be made into accessible SVG very easily.


The authors are grateful to the National Eye Institute, National Institutes of Health for a SBIR (Small Business Innovation Research) grant supporting development of end user hardware and software. They thank the National Science Foundation for SBIR grants supporting development of authoring/editing software.


The Window-Eyes screen reader for blind and severely dyslexic people, GW Micro, Inc,
JAWS screen reader for blind people and other products for people with print disabilities are available from Freedom Scientific, Inc.
TextHelp screen reader for people with learning and cognitive disabilities,
Kurzweil text readers scan text on printed pages, OCR the text, and read it. Models designed for either blind people or people with learning disabilities are available
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