The different types of assistive technology for the blind are computer screen readers, braille input and output devices, and text-to-speech software. Screen-magnifying programs are available for computer users with varying degrees of visual impairment. Different types of assistive technology can be used together for students and professionals, depending on their individual needs and preferences. The design goal of each assistive technology software package is to make certain tasks as possible for blind users as for sighted individuals.
Screen-reading software is a common type of assistive technology for the blind. Many screen readers include interactive features that both read aloud text on the screen and guide users through screen navigation. When visually-impaired users open a document with an activated screen-reading program, a built-in voice synthesizer plays the words out loud in the language of choice. Users can often use the text-to-speech tools included with a screen reader package to make their own audio files of various documents.
Optical character recognition (OCR) is a feature of more advanced screen readers for desktop or laptop computers. OCR technology works in conjunction with a document scanner to render the words in paper documents so that the software's speech synthesizer can recognize and play them back. Unlike many regular scanner software packages, this type of assistive technology for the blind does not render paper documents as images. These features make information printed on paper available to the visually impaired as an alternative to braille writing.
Assistive technology for the blind also makes reading and writing in braille easier and more automated for people with higher levels of blindness. Portable digital braille tablets work in a similar manner to laptop computers, as users type in text with a keyboard that has raised braille letters on each button. These braille documents can then be uploaded to a computer where they are then translated into spoken text with a screen reader. An additional option is to print typed braille documents with a specialized printer. These printers for braille output create each letter by punching the correct series of indentations in thick paper with a set of small metal pins.
Computer screen magnifiers are tools for individuals with limited ranges of vision. These programs are typically more comprehensive than standard magnification tools found in the accessibility tools section of most operating systems. This area of assistive technology for the blind helps with word visibility through the use of larger zoom ranges and of limited screen colors for greater clarity.