Vol. 6, No. 3 May/June 1998	Previous Issues Subscribe to AT Messenger Download PDF Viewer
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Video Magnifiers: Making Print Larger

by Ed Salisbury, Kent County AT Specialist

The video magnifier commonly referred to as a closed circuit television (CCTV) is used by people with visual impairments to magnify printed material. CCTVs are able to magnify such things as books, magazines, daily mail, and maps. CCTVs, like many assistive devices, vary widely in quality, features, and price. It is important to become familiar with the various features and components of video magnifiers in order to choose one that best meets individual needs. In addition, an evaluation by a low vision specialist is very important in determining whether a CCTV will be beneficial.

Components

All CCTVs, regardless of size and appearance, consist of several essential components. The first is a CCD video camera fitted with a special zoom lens and a light source. Second, and equally important, is a video display. Video displays used with CCTVs include composite monitors and television screens. Although more expensive than conventional televisions, monitors generally provide higher image resolution and higher contrast., both of which are important to the readability of enlarged text. The third essential component is a means of positioning the printed material beneath the camera. This is generally accomplished using an X/Y positioning table. The X/Y table can move simultaneously in both the horizontal and vertical axes, allowing quick and effortless access to any area of the printed page. The above components are standard on most CCTVs.

Types of CCTVs

CCTVs fall into several categories. The most common type of CCTV is the all-in-one style. In this configuration, all components are stacked vertically and placed within a metal or plastic casing. This type of CCTV generally is the most portable and takes up the least desk space. Also common is the modular style of video magnifier. Components can be stacked vertically, like the all-in-one models, or arranged side-by-side allowing for maximum flexibility and comfortable access. Portable CCTVs consisting of a hand-held camera and a miniature television screen or even a “virtual reality” style of monitor, are popular for use by people who need text magnification in all environments. These portable systems can be used to read price tags at retail or grocery stores, menus, small signs, etc. Some systems interface with the computer, taking advantage of the high resolution of VGA monitors. These systems allow the magnified image to be placed in a window on the computer screen and viewed simultaneously with computer output. This type of system is excellent for students and professionals who need access to a variety of reference material when composing reports and other documents. One software program is able to give the user the benefits of a CCTV using a computer and image scanner. This software provides not only an inexpensive alternative to the standard CCTV but includes many features not available with video magnifiers.

Features

Price and usefulness of a CCTV are generally dependent on its features. Features of the X/Y table that are important to many users include: motorization of the table for hands-free panning; adjustable friction control for those who wish to position the document manually; the ability to lock the X/Y table into a particular axis for easy row or column viewing; and larger size tables to accommodate several documents or oversized books. Features of the camera include focus free lenses for quick and easy changing of magnification level and zoom factors of up to sixty times magnification or more. Features of the monitor include size, resolution and placement. Larger monitors provide a greater area of magnification at the same zoom level than smaller monitors do. This decreases the need for constant panning using the X/Y table. The ability to swivel or tilt the monitor improves comfort and readability. CCTVs are also available in black and white, monochrome, or color. Black and white CCTVs only provide text/background reversal to increase contrast. In other words, the user can see standard black text on a white background or white text on a black background. Monochrome versions allow the user to customize contrast by providing the ability to assign a variety of colors to text and background. Color CCTVs actually magnify in the full color of the document. This feature is excellent for viewing maps and photographs. Some models provide a feature for underlining or masking blocks of text. This is an ideal feature for those who tend to lose their place on the page.

Who Needs a CCTV?

CCTVs are generally of most benefit to those who require a higher magnification than what most hand held magnifiers provide. For those who have difficulty holding a magnifier, regardless of magnification level, the CCTV provides obvious advantages. Also, the CCTV allows one to remain in a comfortable reading position reducing back and neck fatigue. In many instances, the ability to change the color scheme for increased contrast is more important than level of magnification. In determining what type and brand of CCTV to purchase, it is very important to consult with or be assessed by a low vision specialist. The Division for the Visually Impaired in Delaware, as well as several other organizations, can be of assistance in this matter. The ATRCs do have several CCTVs available for short-term loan. For further information on specific brands, as well as information on where to obtain an assessment and funding, contact your local ATRC.