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    May 15, 2005
    Overscan And Widescreen DVDs
    Dear Gary:

    I’ve been a reader off and on since your first issue. Back then I was OBSESSED with widescreen LaserDiscs and when I found your magazine with the title, Widescreen Review, I was definitely intrigued.

    I’d like to see articles and/or a column on the effect “overscan” has on what the viewer is able to see on the various screen formats (CRT/Plasma/LCD, etc). I absolutely hate having ANY information not available to see, no matter how scant. I’d like to know if ZERO OVERSCAN can be achieved from any of the screen formats available. I know it’s difficult with my CRT. On my LCD computer screen, I see absolutely EVERYTHING, resulting in some significant windowboxing on some titles (Deliverance, Blade Runner, for example).

    Steven Martinez



    Video Technical Editor Greg Rogers Comments:

    The amount of overscan produced by a CRT display depends on its calibration, usually adjusted in a service menu. Most CRT projectors and monitors can be calibrated for zero overscan, but many broadcast sources do not fill the entire video frame. They may have noisy edges that are objectionable to view. Some DVDs, and other pre-recorded sources, may also not fill the entire frame. Hence, most users prefer to have about 2-3 percent overscan at each edge of the screen, but you could have your CRT display calibrated for less overscan. Professional CRT monitors usually have a user switch to change from zero to some small value of overscan, but that feature is seldom found on consumer CRT projectors or monitors.

    The amount of overscan on a fixed-pixel projector or monitor (LCD, DLP, Plasma Panel) is determined by its A/D converter system (for analog signals) and its built-in scaler (for analog and digital signals). Each incoming video format (480i/p, 720p, 1080i/p) must be scaled to "fit" the display's native pixel resolution. The scaler can be engineered to produce any amount of overscan that its designers want it to have. In some cases, there will be a user choice to select zero overscan or some nominal (2-3 percent) amount of overscan. Sometimes there is the ability to position the active (visible) video, which allows the user to adjust for equal overscan at each edge of the screen. Each of my reviews report the amount of overscan for each video format, differences between analog and digital input signals if they exist (usually they do), and if the overscan can be centered (positioned) by the user.

    You can E-mail Widescreen Review @ mailto:editorgary@widescreenreview.com

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