OTHER TECH

Overscan Tune-up

Q. I have the Sound & Vision Home Theater Tune-Up DVD and would like to check the overscan of my rear-projection TV and fix it if needed. There are two test patterns that look like they could be used for this: Anamorphic Resolution (WSE) and Resolution 200 TVL. I know overscan is measured in percentages, but there are no percentage marks on these - only the letters A to G. How do I use these patterns? Sherman Maddox Lewisburg, TN

A. Al Griffin says: The term "overscan" refers to the amount of valid picture information in the signal that's hidden or lost beyond the edges of your screen. Every TV has some modest overscan to prevent you from seeing the distracting edge of the video frame. You're correct that there are two patterns in the Tune-Up disc's menu of advanced video test patterns that can be used to check overscan. The first, Anamorphic, is for widescreen (16:9) TVs, and the second, Resolution 200 TVL (TV lines), is for standard (4:3) TVs. With either one, you'll see a bold white line bordering all four sides of the pattern. That line is the 5% overscan marker. Outside that perimeter are five fainter lines representing overscan percentage points 0 to 4. To figure out your TV's overscan percentage, simply display the relevant pattern and check how many lines are visible beyond the 5% marker. If for some reason you can't see the 5% marker, your TV is likely in need of professional help; adjustments for overscan can usually be made only from the TV's service menu.

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