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Overscanning

To complicate matters even more, there is a third choice in aspect ratios for televisions available. This is the 16:10.7 aspect ratio TV. It is available in only a few models (e.g., Pioneer), but it is a very interesting television. It turns out that TV sets incorporate what is called "overscanning". This means that part of the image lies outside the viewing area of the TV screen. In a way, it is like matting your photos in a frame by overlaying the outside edges of the photo with the cardboard matte. This hides any rough edges. Overscanning accomplishes the same thing, hiding the rough edges of the broadcast signal plus a little extra just for good measure. These rough edges are caused when the electron beam, having scanned a line, returns to the left edge of the screen ("blanked", i.e., not visible during this time), and then begins another scanning line back across the screen. It takes a small amount of time for the beam to settle down, and something called "ringing" occurs. This results in a distortion of the image along the edges. Depending on the quality of the TV, the amount of overscanning can be up to about 8% so that this ringing will not be visible. The 16:10.7 aspect ratio Pioneer TV has less overscanning than the average TV, so a little more picture is visible on the sides of this rather unique television, and you might want to check one out, comparing side by side the images with those on a conventional set. For widescreen movie fanatics, some of the new DVD players will let you "zoom" the image, making it larger or smaller. In the case of a widescreen movie, you can reduce the image size a little, and this brings the overscanned areas on the right and left sides in so you can see them.