Closed circuit video magnification systems are capable of higher levels of magnification and they are able to manipulate the brightness and contrast of the image. Video magnification has been reported in the literature for over four decades.
The concept of a CCTV is simple. A video camera is used in real time to capture the image of the reading material and display it on a monitor.For example, the poor contrast of newspaper print can be enlarged 40X, but can simultaneously be converted to white letters on a black background. The CCTV evaluation should include testing with real world items including newspapers, telephone books, utility bills, an addressed envelope, a handwritten letter, a greeting card, magazines, a checkbook, photos, a can of food, a medicine bottle, the patient’s fingernails, a tax form, an address book, a recipe, and jewelry.Filling an insulin syringe or performing glucometry should be demonstrated for the insulin dependent diabetic. Preferences for image size, type of contrast, color and the ability to operate the system should be determined.Motion problems from moving the image on the screen may be reduced with larger monitors that allow displaying more text at one time.
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