Visual Displays and Indicators

Visual display is the predominant form of display on today’s computers. This includes the standard display screen, light-emitting diode (LED) or liquid crystal display (LCD) icon displays on or near the keyboard, and special visual indicators on peripheral devices.

For people with low vision or blindness, these displays are a barrier to computer use. Special screen-magnification software can increase the image size for people with low vision. Similarly, software “screen readers” can access information and read it aloud to users who are blind. Information provided by indicator lights or LCD mini-displays, however, must also be made available and readable.

Hardware design strategies for providing greater access to visual information include the following:1.Minimize glare.

1. Glare caused by reflections or mismatched color combinations, overly bright indicators, and so on might present problems for users with low vision. Minimizing glare allows these users greater access to displays.
   
   
2. Avoid 5-Hz to 50-Hz refresh rate or flicker rate.

   This allows users with photosensitive epilepsy, who might have a seizure if exposed to strong stimuli in the 50-Hz range, to more safely use the system.

   
   
3. Make LCD and LED indicators, warning lights, and alert lights software-readable.

   This allows users who are blind to use their screen-reading software to access important indicators, warnings, and notices.

   
   

   The following standard design practices also facilitate accessibility:

4. Provide contrast and brightness controls.

   This is important for users with low vision and color blindness, making it possible for them to adjust the display to accommodate their needs and preferences.

   
   
5. Provide a display connector for an external or additional monitor.

   Users with low vision often need to augment the system with a larger monitor to take full advantage of screen-magnification software. This is especially true for mobile PC users.

   
   
6. Provide adjustable monitors.

   Users with physical disabilities adjust the angle and position of the monitor to suit their seating position and approach to the system. Other users with low vision often adjust the monitor to reduce glare.