There are two types of screen magnifications that people generally refer to: screen enlargement software and closed circuit televisions (CCTVs). Computer screen magnification for individuals who are visually impaired is essentially analogous to an individual who is blind using speech synthesis; each of them accessing the computer monitor. CCTVs for the visually impaired can be said to be analogous to reading systems for the blind since both functions are attempting to access printed material.
Screen enlargement software can magnify the text and graphics on a computer screen in various ways. The Windows version software allows the user to magnify a single line underneath the cursor, magnify an area of the screen, or magnify the entire screen and the magnification can range from 1.5 times to 16 times the normal size of characters. Depending upon the particular software, there are also numerous other variations and combinations of the above features, including an option to have the program automatically scroll through the document. Screen enlargement software also allows the user to alter the color of the text and the color background. For example, if the user is light sensitive but needs contrast, they may wish to have the text displayed in bright yellow on a soft gray or powder blue.
Screen enlargement can be used effectively with speech synthesis. If used in tandem, the user can have certain features of an application program spoken while their concentration is focused where they have the magnified text.
Closed circuit televisions (CCTVs) are essentially electronic magnifiers. There are four basic types of CCTVs; these include: NTS interface, portable, stand alone, and computer interface. The distinction between these units is mostly in their configuration, but they all achieve similar purposes.