 |
Abstract | Market Needs | State-of-the-Practice | Issues to Consider | References
Advances in technology make the creation and incorporation of graphics easier than ever before.
Consequently, the use of graphics is growing. This is evidenced by the proliferation of visually
complex websites and the emergence of newer technologies such as interactive public kiosks,
telecommunications devices with visual displays, electronic textbooks, and multimedia
presentations with interactive visual displays and simulations. Graphics can provide essential
information related to the topic being presented. The visual nature of graphics presents a
significant problem to individuals with low vision and blindness. Access to graphics is a high
interest area identified by consumers, researchers, manufacturers and educators. There is a high
priority need for technology that provides fast access to graphics with less intervention required.
Technological advancements in this area represent significant business opportunities.
[ Top of Page ]
Graphics embedded in print material are as integral to the learning process as the textual
materials in which they are found. For the estimated 7.7 million individuals who have difficulty
seeing, but have retained usable vision, access to graphics can be obtained by enlarging or
reducing the images, altering the image color and providing higher contrast (McNeil, 2001). For
many people with visual impairments, access to graphics must be obtained by providing the
information contained in graphics in an alternative format (Shoemaker, 2002). These formats
include tactile representation, auditory descriptions, auditory sounds and haptic effects such as
pressure, vibration, texture and temperature.
Access to graphical representations of information is especially important for many high
technology careers, including careers involving mathematics and science. Equally important is
the assurance that the estimated 448,000 school age children who have visual impairments are
provided with access to graphics for coursework in math, sciences, history, and geography
(Adams, Hendershot and Marano, 1999). Tools that assist children with visual impairments to
understand graphical representations will enable them to consider high-tech careers that would
have been difficult or impossible without this access.
From the user perspective, every learner stands to benefit from information made accessible in
more than one way (IMS Global Learning Consortium, 2002). This is especially true when the
content is complex. For example, a graphic of a science diagram in an electronic textbook may
be difficult to interpret, even by individuals without a visual disability. A text description would
augment and reinforce the content of the graphic and benefit a wider range of students. From a
technical perspective, flexible graphic content can be accessed on multiple platforms including
PDAs and cell phone displays. The challenge of presenting multimodal access to graphic
information is on the cutting edge of accessibility research and many problems have yet to be
solved. By supporting graphical content with multimodal output, developers improve the
prospects of all learners who use their products and increase the marketability of their products.
[ Top of Page ]
Graphics can be categorized in a number of ways. For the purpose of this White Paper, three
types of graphics and two methods of obtaining access to these graphics are considered. Types of
graphics include static, dynamic, and interactive. Methods of access include direct access and
indirect access. Direct Access implies that the person with a visual impairment can obtain the
needed information directly from the graphic presented without any sighted intervention or
assistance. An example of this is a static tactile graphic. Indirect Access requires that the
information provided first be interpreted and then provided in an alternative format. A verbal
description of the photograph by a sighted reader is an example. In this case, the indirect access
is dependent. If the same description was stored in text, Braille or on audio tape, access to that
same information, while indirect access was required, is independent. In any case, indirect access
implies a modification to the information has occurred.
Independent access to graphics, whether provided directly or indirectly, is a high priority need
for individuals with a visual disability. Because indirect access implies preparation time and
skill, direct access is especially important for dynamic and interactive graphics where change
occurs in real time. Interactive access to graphics requires that both the input method and the
resulting graphic and textual information be accessible. Technology, including assistive
technology, can be used to provide access to graphics. The following is an overview of
technology currently in use or in development to meet this need. For each technology, the type of
graphics it addresses and the access method are noted.
Static Graphics are those that are fixed or stationary regardless of the medium used to display
them. Static graphics can be simple or complex and stored on paper as well as on the computer.
Examples include photographs, paintings, drawings and diagrams, maps, charts, graphs, symbols
and higher-level science and math equations. Static graphics that can be accessed directly are
those which are located in print media (not those which are computer based). They include the
following:
Magnifying glass
Access to static graphics by persons with low vision may be facilitated through the use of a
magnifying glass. Hand held magnifiers are typically used in viewing printed material. When
placed in close approximation to a desired object, the perception of the object is enhanced
according to the distance from the object. Lenses are available with varying magnitudes of power
ranging from 1.8X to 5X.
Tactile drawings and images
Access to static graphics can be provided by converting them into tactile drawings. The image
can be photocopied or printed onto specially coated paper (capsule paper, swell paper) and then
heated by using a fusing machine or traced with a heat pen. Dark lines on the heated, coated
paper swell and create a raised image that can be felt. Print diagrams are designed for visual
readers and often contain features such as perspective, overlapping lines, color, print labels,
icons and complex components that make it difficult to create a tactile drawing without first
simplifying and or resizing it. Graphics on paper can be scanned into the computer and graphics
stored in an application program or on a web page can be copied and pasted into a program with
drawing tools where it can be altered to make it easier to read tactually (Tactile Access to
Education for Visually Impaired Students (TAEVIS), 2002).
Static graphics that are accessed indirectly include the following:
Video magnification devices
For people with low vision who benefit from large print, access to static graphics can be
provided by using a digital video magnifier (CCTV) if the graphic is not stored on the computer.
If the graphic is in color and if the color imparts information, then a color video magnifier can be
used.
Graphic Embossers
For people who are blind, access to static graphics can be provided using an embosser. If a
diagram is stored electronically, it can also be sent to a specialized graphic embosser capable of
accepting a graphic directly from a Windows-based application. One difficulty with this access
method is that the rendering of the image requires the time and skill of a person acting as the
tactile illustrator. Another difficulty is that the graphic itself, although resized and simplified,
requires skill and practice to read and may be hard to interpret independently using only the
sense of touch.
Vibrotactile displays
Vibrotactile displays are haptic displays that incorporate the interpretation of vibratory
stimulation to convey information about the environment. These devices, such as the Optacon,
may be used to aid in reading tasks for people who are blind. The Optacon converts print or
computer output into an enlarged, vibrating tactile form. To read, the user moves the Optacon
camera across a line or print with one hand, while placing the index finger of the other hand on
the tactile array. As the camera moves across the letter, the image is simultaneously reproduced
on the tactile array by vibrating tools. The person perceives the vibrating image with the index
finger (Lane, 1997).
Mark-up Languages
There are a number of current and developing tools that can be used to provide alternate output
to graphics stored on a web page that increase accessibility for individuals with a visual
impairment. Those that provide indirect access to static graphics include the following:
- XML (Extensible Mark-up Language): Auditory access can be provided by adding text
identification and text description of graphic images. These descriptions are sometimes
referred to as "alternative" or "alt" text or "tags." Use of XML provides tags that are more
flexible than HTML that can be used to provide long descriptions of graphic content or that
can be read with a screen reader or refreshable Braille device.
- SVG (Scalable Vector Graphics): Static graphics stored in SVG format rather than as
bitmaps have many advantages for providing accessibility. Bitmap images are made up of
pixels in a grid. Bitmap images are resolution dependent. Therefore it is difficult to increase
or decrease their size without sacrificing image quality. Vector images are made up of
scalable objects defined by mathematical equations rather than pixels. Because they are
scalable, the size of vector-based images can increase and decrease in size without altering
the image quality. Vector objects can be placed over other objects and the object below will
show through. They are text-based and can provide a hierarchical relationship between labels
or grouped labels which can be an advantage for diagram description. Search engines and
screen readers can identify and read text within the image.
- MathML and ChemML: Currently screen reading software for users with visual impairments
cannot accurately read most scientific or mathematical expressions. MathML is a powerful
new language for encoding mathematics. MathML stores information about the logical
structure and meaning of equations as well as their appearance, which can be accessed. This
is not the case when an equation is stored as an image. Chemistry often has 2D and 3D
representations of chemicals and chemical structures that need to be rendered on the screen
(Freed, Rothburg and Wlodkowski, 2003). The chemistry equivalent to MathML is ChemML
(Murray-Rust and Rzepa, 2001). Screen readers cannot yet read MathML or ChemML.
However, research and development efforts will soon make this possible. A second possible
markup language for scientific or mathematical expression display is LaTeX. Tools do exist
for converting LaTeX to Nemeth Braille for blind users [Note: Nemeth Braille is a form of
Braille used to represent mathematic equations linearly (Dotless Braille Organization, 2002)].
Dynamic Graphics are representations of graphic information that are continuously changing.
They may also be graphics that change intermittently or graphics that are subject to change.
Examples of dynamic graphics include movies, videos, cartoons, and medical instrumentation
such as sonograms, Electrocardiograms and CT scans. Dynamic graphics can be accessed only
indirectly. The following are included:
Video magnification software
For people with low vision who benefit from large print, access to both static and dynamic
graphics (such as a video clip) can be provided by using magnification software if the graphic is
stored on the computer. Difficulties in using these devices include visual access to only part of a
diagram at one time and lack of access to the technology because of cost, portability or
incompatibility issues.
Descriptive video
Audio descriptions provide access to multimedia and dynamic graphics for people who are blind
or visually impaired by adding narration that describes the visuals, including action, scene
changes, graphics and on-screen text. Creating meaningful audio descriptions requires
specialized training in how best to convey visual images verbally. The narration should be
carefully written to fit precisely into the natural pauses in program dialog (IMS Global Learning
Consortium, 2002).
Synchronized Multimedia Integration Language (SMIL) is an XML language that manages
the integration of alternative formats including sound, text, video and pictures. These elements
are stored separately and synchronized at the time of playback. SMIL-formatted multimedia can
be delivered via the internet or locally via a CD or DVD-ROM. When authored correctly, SMIL
allows users to turn captions and descriptions on and off via a player interface (IMS Global
Learning Consortium, 2002).
Interactive graphics are graphics, both static and dynamic, that are subject to change based on
input from the user. Examples include video games, computer applets, visual simulation displays
and oscilloscope screens. Interactive graphics can be accessed only indirectly. The following are
included:
Digitizing tablet with audio output
This system consists of a touch screen connected to a computer. A tactile graphic sheet is placed
on the touch-sensitive surface. When a user presses points on the tactile, the finger pressure is
transmitted through the touch screen. By comparing the position of each pick against a database
of predefined hotspots, the computer is able to provide identifying audio feedback to the user as
a confirmation and elaboration of the information supplied through touching (Touch Graphics,
n.d.). Talking, programmable tablets have been released in the past, and a newer, easier to
connect model with added features has just been released. These systems have great potential in
providing independent access, but require programming of materials to correspond with tactile
drawings.
Audio-Accessible Graphing Calculator
The Accessible Graphing Calculator is a self-voicing graphing scientific calculator developed in
the Science Access Project at Oregon State University. Unlike a hand-held calculator, it displays
results through speech and sounds as well as visually presenting numbers and graphs. The sound
guides the user along the graph lines with pitch. It provides access to interactive graphic output
using audio sound or by printing the resulting graphic on a graphic embosser. The Accessible
Graphing Calculator is now in commercial distribution (ViewPlus Technologies, 2003).
Auditory oscilloscope
The auditory oscilloscope allows users to access information about a waveform using auditory
feedback. The horizontal feature of a wave is indicated by the location of the scanner as
controlled by the user. Variations in pitch of the output gives users information associated with
the slope of the waveform as it rises and falls. This device will prove beneficial to students and
professionals in the mathematics, sciences, and engineering fields (Smith Kettlewell Eye
Research Institute, 2002).
WinTriangle Scientific Word Processor
The WinTriangle Scientific Word Processor is an extension of the DOS Triangle program. It
uses a standard RTF format allowing files to be read, edited, and created by people with and
without vision impairment. In addition to word processing capabilities, WinTriangle is able to
interpret and provide the user with speech output inclusive of mathematical and scientific
symbols and terms (Science Access Project, 2003).
Haptic access
The haptic sensory modality is based on subcutaneous receptors and kinesthetic receptors found
in muscles, tendons, and joints (Loomis and Lederman, 1986). Kinestesia and force feedback are
elements of haptic perception used to perceive texture and shape. Research has shown that with
free exploration, familiar common objects can usually be identified haptically, without vision
(Klatzky, Lederman, and Metzger, 1985).
There is currently no technology available to provide direct tactile access to images (static,
dynamic or interactive) stored on a web page. However there are a number of "touch-enabled"
mice, joysticks and trackballs commercially available that use Immersion TouchSenseTM
technology. Software developers are beginning to incorporate use of these peripherals and a
number of games and software with haptic feedback is growing. There are also a number of
projects under development. The Haptics Periodic Table, currently in development, will allow
students to hear the relative locations of elements within the periodic table. It will also be
possible to "feel" the relative atomic weight of an element, hear about the element's uses and
history and learn about relationships represented within the structure of the table (Network for
Inclusive Distance Education, n.d.). The Phantom is a computer interface system with pivoting
thimble-like receptacles mounted at the ends of computerized arms, into which a person can
insert their fingers and then virtually "feel" the shape, texture and weight of objects on the
computer screen as well as virtually "manipulate" and otherwise interact with those objects
(SensAble Technologies, 2003).
[ Top of Page ]
- What needs do people with visual impairment have in accessing graphical information?
- Which of these needs are most critical?
- What technologies are available to address these needs?
- What are the strengths and weaknesses of these technologies?
- Which of the critical needs are not well met by these existing technologies?
- What capabilities should an ideal technology provide in order to access graphical
information?
- What resources (e.g., research, technology developed in other fields) could facilitate the
development of the ideal technology?
- What barriers (e.g., cost, feasibility, policy) will hinder the development of the ideal
technology?
[ Top of Page ]
- Adams, P. F., Hendershot, G. E., & Marano, M. A. (1999). Current estimates from the national
health interview survey, 1996. Retrieved January 22, 2004, from
http://www.cdc.gov/nchs/data/series/sr_10/sr10_200.pdf
- Dotless Braille Organization (2002). The Nemeth Code. Retrieved August 5, 2004, from
http://www.dotlessbraille.org/nemethcode.htm.
- Freed, G., Rothberg, M., & Wlodkowski, T. (2003). Making educational software and web sites
accessible: Design guidelines including math and science solutions. Retrieved January 7,
2003, from http://ncam.wgbh.org/cdrom/guideline/expanded.html
- IMS Global Learning Consortium, Inc. (2002). IMS guidelines for developing accessible
learning applications version 1.0. Retrieved March 19, 2003, from
http://www.imsproject.org/accessibility/accessiblevers/index.html
- Klatzky, R., Lederman, S. & Metzger, V. (1985). Identifying objects by touch: an
expert system. Perception and Psychophysics, 37, 299-302.
- Lane, J.P. (1997). Project summary: Identification, evaluation, development, transfer and
commercialization of Federal Laboratories technology for the assistive technology
marketplace. Planar tactile graphics display (pp. 80-121). Buffalo, NY: Technology
Transfer Rehabilitation Engineering Research Center.
- Loomis, J., & Lederman, S. (1986). Tactual perception. In K. Boff, L. Kaufman, and J.
Thomas, Eds., Handbook of Human Perception and Performance (pp 1-41).
New York: Wiley.
- McNeil, J. M. (2001). Household economic studies: Current population reports: Americans
with disabilities 1997. Retrieved January 23, 2004, from
http://www.census.gov/prod/2001pubs/p70-73.pdf
- Murray-Rust, P., & Rzepa, H. S. (2001). Chemical markup language. A position
paper. Retrieved April 10, 2001, from
http://www.xml-cml.org/information/position.html
- Network for Inclusive Distance Education. (n.d.) Haptics periodic table. Retrieved
February 17, 2004, from http://nide.snow.utoronto.ca/hperiodic.htm
- Science Access Project (2003). WinTriangle: A scientific word processor for the blind.
Retrieved March 19, 2003, from http://dots.physics.orst.edu/wintriangle/
- SensAble Technologies (2003). The Phantom. Retrieved March 19, 2003, from
http://www.sensable.com/products/phantom_ghost/phantom.asp
- Shoemaker, J. A. (2002). Vision problems in the United States: Prevalence of adult
vision impairment and age-related eye disease in America. Baltimore, MD:
Prevent Blindness America.
- Smith Kettlewell Eye Research Institute (2002). Section I. Vocational technology.
Retrieved March 19, 2003, from
http://www.ski.org/Rehab/Compendium/General/I.html#anchor109366
- Tactile Access to Education for Visually Impaired Students (TAEVIS). (2002). Tactile
diagram manual: 2002 edition. Purdue University. Retrieved March 19, 2003,
from http://www.taevisonline.purdue.edu/Tactile_Diagram_Manual.html
- Touch Graphics. (n.d.). Talking tactile tablet. Retrieved February 16, 2004, from
http://www.touchgraphics.com/ttt.htm
- ViewPlus Technologies. (2003). ViewPlus Accessible Graphing Calculator. Retrieved
February 16, 2004, from http://216.157.142.20/custompages/custom13.html
[ Top of Page ]
|
|
