In order for visually impaired individuals to use computers, there are number of software and hardware developed, and these are referred to as assistive technologies. They include screen readers, screen magnification programs, and braille displays. In this part of the presentation, these assistive technologies are briefly explained.
The very basic purpose of screen readers is to convey what is on the screen to users through speech output. Screen readers, however, do much more than merely reading the screen and below are some of key features often available in screen readers.
This is set of functionalities to allow users to find out what is displayed in any part of the screen. Review functionalities are essential since what has been spoken does not remain in the scene to be reviewed unlike information presented visually on the screen.
There are variety of functionalities for this purpose. Allowing users to use the arrow keys to explore the screen is the simplest functionality. Many screen readers provide functionalities to let users specify certain area on the screen, or on an application program's window and enable them to access the information presented in the area with very simple key stroke.
According to the configuration, screen readers echo what users type in from the keyboard. Since many visually impaired users cannot look at the screen and assure that their typing is correct, this functionality is helpful, especially to beginners.
Many screen readers let users use the keyboard to perform the same task as with mouse. Specifically, users can use the keyboard to move the mouse pointer and click on objects. Also, some screen readers simply make the mouse pointer follow the caret unless the user configures differently. These functionalities let users perform tasks mouse-free, and improves the productivity.
Screen magnification programs allow users to enlarge text and images on the screen. Users can choose arbitrary part of the screen to be enlarged. They also let users adjust the foreground and the background colors, so that users can work with preferable color contrast.
Depending on product, number of braille cells differs, i.e. number of braille characters which can be displayed at once differs. Most products have between 40 and 80 cells. In general, braille displays with more cells improves the efficiency of works.
Since braille displays can show only a line or less at a time, keys on the display unit are usually configured to be used to manipulate the display. Users can use these keys to read different parts of screen in braille. It is important to understand that what users are reading are fragments of what is on the screen and they need to re-assemble them into an image of entire screen or window. This process can be extremely difficult for some visually impaired individuals.