What are Screen Magnifiers?

Software that interfaces with a computer’s graphical output to give enlarged screen content is known as screen magnifier. This assistive technology can be useful for visually-impaired people with some functional vision.

The simplest way to magnify is to enlarge a portion of the original screen content to full-screen or to another optimal size. The enlarged portion needs to be that of user’s interest or selection. The pointer or cursor also needs to be suitably enlarged. The screen magnifier should track the movement of the cursor and enlarge the latest selected portion. This tracking should be smooth, as jerking or flickering may disturb the user.

If the user prefers using a keyboard, rather than a mouse, the magnified portion needs to be moved in accordance with the keyboard functions. For example, if the user presses a keyboard shortcut that opens a menu, the magnified portion should jump to that menu. Pop-up windows and changes in system status can also trigger this rapid shifting.

Generally, magnification ranges from two to 36 times. Some of the most common screen magnifying software applications are ZoomText, Lunar Plus, Magic and Bigshot. These magnifiers can magnify up to 32x. The degree of magnification is inversely proportional to the volume of the viewable content. For example, the more you magnify the less content you see. So, the user needs to choose an optimal magnified size, rather than the largest one. With two times magnification you have only 25 percent of the screen left, with three times magnification this is only 11 percent and 32 times leaves no more then 3.2 percent of screen of the original size.

Screen magnifiers provide several other features for visually-impaired people:

• Color inversion. Inversion of the colors is preferred by many people with visual impairments. For example, turning text from black-on-white to white-on-black can reduce screen glare and is useful for people suffering from macular degeneration.
• Smoothing. Enlargement makes text blocky and difficult to recognize. Some screen readers can smooth text to solve this problem.
• Cursor customization. The cursors can be modified to easily locate them on the screen.
• Different magnification modes. The enlarged portion can be specified full screen, a movable lens or a fixed magnified portion.
• Screen reader. Some magnifiers offer a basic screen reader, which can read out whatever the user is pointing at.