Screen enlargement programs, also called magnification software programs, are designed for computer users who are low vision. Their function is mainly to magnify the screen, because the assumption is that the intended users have enough vision to read information from the screen. In recent years, however, in addition to magnification, the most commonly used screen enlargement programs give users the option of reading text from the screen. The reading capabilities of these programs are not as advanced as those of screen readers, so it is not advisable to use a magnification program to satisfy the needs of a screen reader user. Since the premise is that a low vision user can see the screen, as long as it is magnified, reading capabilities are quite limited and not as reliable.
What is valuable in a good magnification software program is the quality of magnification (the more the screen is magnified, the more the quality tends to deteriorate), the option to set various colors for the mouse and for the Windows interface (i.e. some users may prefer to have a dark background and light letters), and tracking (the focus has to change as a user moves on the screen). In other words, if a text is typed, the magnification software has to move along the screen and enable the user to see what he is typing. This becomes extremely important when a higher magnification is used. When a user sets the magnification to 2x, this movement may still be of minor importance, because most of the screen is visible. But when magnification is raised to 4x or 6x, the user can see only a fraction of the screen.
Some of the features of magnification software programs may not work correctly in certain applications, especially in those less commonly used. They will, in the vast majority of cases, perform their major function without fail: they will magnify the screen. They can be installed on any computer, with any fonts, including Chinese characters, Cyrillic, Greek or Arabic characters and, even though they may fail to read them, they will still enlarge them. The most commonly used magnification software programs are ZoomText by AiSquared, Lunar/Lunar Plus and SuperNova by Dolphin Systems, and Magic by Freedom Scientific.