There are two categories of visual impairments. Individuals who are partially sighted (for example, blurred vision, near
and far-sightedness, color blindness) and those who are totally blind. Assistive technologies are available for the Linux
operating system for visually impaired users, and many of the software packages are free.
Screen readers are software applications that are installed on the computer to provide translation of the information
on the computer screen to an audio output format. The translation is passed to the speech synthesizer and the words are spoken
out loud. Currently, fully functional screen readers are only available for Linux in console mode. This section describes some of
the most common screen readers.
Emacspeak is the complete Audio Desktop is an excellent non-graphical, text
based interface for users who are visually
impaired. This application can be used as a screen reader in conjunction with a hardware synthesizer or IBM ViaVoiceŽ
Run-time text-to-speech application. More information and software packages of are available at:
http://www.cs.cornell.edu/home/raman/emacspeak/. The Emacspeak HOWTO
http://www.ibiblio.org/pub/Linux/docs/HOWTO/ includes a tutorial and
installation guide.
Jupiter Speech System is a screen reader for Linux in console mode. A user guide
and software packages are available at:
http://www.eklhad.net/linux/jupiter/.
Screader is a screen reader for Linux in console mode that works with the
Festival software speech synthesizer and the Accent hardware synthesizer. Information and downloads are available at:
http://www.euronet.nl/~acj/eng-screader.html.
Speaker is a new plugin for the Konqueror file manager and Web browser.
Speaker provides Text to Speech using the Festival speech system or IBM ViaVoice. Downloads are available at:
http://dogma.freebsd-uk.eu.org/~grrussel/speaker.html.
Speakup is a screen review package for the Linux operating system. It requires
a hardware speech synthesizer, such as the DecTalk Express. An installation boot disk and packages are available at: http://www.linux-speakup.org/ that allow a
visually impaired user to install the Linux operating system.
Speech synthesizers can be a hardware device or a text to speech (TTS) software application that creates the sounds
necessary to provide speech output. Hardware synthesizers are available for the Linux operating system; however, they can
be very expensive and must be compatible with the screen reader application in order to function properly. The alternative is to
download and install a software synthesizer such as IBM's ViaVoice or Festival and configure the application to a compatible
screen reader, such as Emacspeak.
A hardware speech synthesizer is a device that is connected to the computer's serial or parallel port and translates the
text to a spoken output. Normally there are Braille labels on all controls to indicate the off and on position, and volume
control. Hardware synthesizers also have the ability to speak in different tones that can be setup to indicate various parts of a
document or text. Some models will provide a connection for headphones. The following is a list of speech
synthesizers that are supported on the Linux operating system and can be used with Emacspeak:
A software speech synthesizer is an application that translates the text on the screen to speech output and provides
speech synthesis, so that the screen reader application can read information out loud to the user.
Festival is a general, multi-lingual speech synthesis system developed at the
Center for Speech Technology Research (CSTR). It offers a full TTS system with various application program interfaces, as well as
an environment for development and research of speech synthesis techniques. Mbrola or FestVox are needed to complete the Festival
installation. Software packages and installation instructions are available at:
http://www.cstr.ed.ac.uk/projects/festival/.
Mbrola is a speech synthesizer that can be used with a TTS application, such
as, Festival to provide speech output. More information is available at:
http://tcts.fpms.ac.be/synthesis/mbrola.html.
Screen magnifiers enable users that are partially sighted to view selected areas of the screen in a manner similar to using
a magnifying glass.
GMag is a screen magnifier for X Windows. It provides continuous magnification
while you work, as well as the option to change the contrast of images at run-time. More information and downloads are available
at:
http://projects.prosa.it/gmag/.
Puff is a screen magnifier for users who need a high magnification of text and
graphics
in X Windows. Puff follows the focus of the mouse or pointer and enlarges the portion of the screen under the cursor. In order
for Puff to run properly on Linux the source code needs to be modified. This application is not a good option for inexperienced
users. The software packages and source code modification instructions are available at:
http://trace.wisc.edu/world/computer_access/unix/unixshare.html.
SVGATextmode enlarges or reduces the font size for users who perfer to work in
console
mode. The normal text screen that Linux provides is 80 characters across and 25 vertically. After SVGATextmode is installed, the
text can be displayed much larger. One example would be 50 characters across and 15 vertically. The program does not offer the
ablitity to zoom in and out, but the user can re-size when necessary. The most current download is available at:
http://freshmeat.net/projects/svgatextmode/.
Do not run try to run SVGATextmode from an X Windows terminal. You must be in console mode for the display to
function properly.
UnWindows is a collection of programs that includes Dynamag, a screen
magnification program that helps the user locate the mouse pointer. The source code is available for Dynamag as a stand alone
application, or the entire UnWindows package can be downloaded at:
http://www.cs.rpi.edu/pub/unwindows/. The entire UnWindows package will not work with Linux without
programming modifications. However, the Dynamag
application can be installed successfully without any additional code changes.
Xzoom is a screen magnifier similar to Xmag that allows the user to magnify
rotate or mirror a portion of the screen. The most current download is available at:
http://filewatcher.org/sec/xzoom.html.
Braille terminals are normally used by individuals who are totally blind and may be hearing impaired as well. A
Braille display uses a series of pins to form Braille symbols that are continuously updated as the users changes focus.
A Braille embosser is a hardware device for printing a hard copy of a text document in Braille. Braille translation
software is required to translate the on-screen text to a Braille format.
The following Braille translation applications are available for download:
Brass is a new program that combines speech and Braille output. The current
version is still in testing and can be downloaded at: http://www.butenuth.onlinehome.de/blinux/.
BrLTTY supports a serial port Braille terminal and provides access to the Linux
console. It drives the terminal and provides complete screen review capabilities. It is available at:
http://dave.mielke.cc/brltty/.
NFBTrans is a freeware Braille translator written by the National Federation for
the Blind (NFB). Software packages are available for download at: http://www.nfb.org/nfbtrans.htm.
Changing the shape and size of the mouse cursor can help users who have a problem following or seeing the cursor. The
X Big Cursor mini HOWTO explains how to configure enlarged mouse cursors with the X Windows system. This HOWTO is available at:
http://www.icewalk.com/doclib/howtos/mini/X-Big-Cursor.html.
Audio can be very useful to users who are visually impaired. In most X Windows desktop environments audio
alerts and sound events can be setup within the desktop control center by enabling sound and verifying that the option to show
sound is activated. You will need to check the desktop users manual for setup and configuration of sound events.
Locktones is an excellent application for providing toggle keys that sound an audio
alert to warn the user that a keystroke has created a locking state such as Cap Locks, or Num Locks. The application can be
downloaded at:
http://leb.net/pub/blinux/.
Linux can also be configured to beep at the login prompt so the user knows when to type in the password. A configuration
utility can be downloaded and installed that can provide this function at:
http://leb.net/pub/blinux/bootmeup/.
Access Mozilla has a goal to build an accessible Web suite: browser, e-mail,
news, composer and chat that conform to the W3C accessibility standards. More information is available at:
http://access-mozilla.sourceforge.net/.
Blind + Linux = BLINUX provides documentation, downloads and a mailing
list that focus on users who are blind. Information and software packages are available at:
http://leb.net/blinux.
National Federation for the Blind's (NFB) purpose is to help blind persons achieve
self-confidence and self-respect and to act as a vehicle for collective self expression by the blind.
Information for blind users, as well as software are available at: http://www.nfb.org/.
Project Ocularis is run by volunteers, and the project's aim is to improve Linux
accessibility through the creation of new free software and the modification of pre-existing free software. More information is
available at:
http://ocularis.sourceforge.net.
Screen is a standard piece of software that allows many different applications
to run at the same time on a single terminal in console mode. Screen has been enhanced to support some Braille terminals
directly. It is available for download at:
http://www.icewalk.com/softlib/app/app_01508.html.
SuSE Linux is the first Linux distribution to support installation of the
Linux operating system and applications that run on Linux in Braille. The Blinux screen reader runs in the background to enable
visually impaired users to work in a Linux console environment. More information is available at:
http://www.suse.de/us/products/susesoft/70news/new_in_70.html.
xocr is an optical character recognition program that scans written text,
such as a book
and translates it to audio output, so the information is available to visually impaired users. More information is
available at:
http://sal.unimedya.net.tr/Z/3/XOCR.html.