Image Processing Reference
In-Depth Information
16:9 image cropped each side
Visible region on 4:3 screen
Figure 11-3
Panning across a frame.
Both of these techniques allow the entire picture area of the display surface to be
covered. The pan and scan parameter values are transmitted for each field and allow the
offset to be described to an accuracy of one sixteenth of a pixel. This allows for very
smooth movement of the raster on the receiver so the viewer is never aware that it is
taking place.
11.9
Aspect Ratio Conversion
An alternative approach is to aspect ratio convert (ARC) the content, but this normally
leads to black bars at the top and bottom or at the sides of the screen. Although this is not
specific to MPEG-2, the description is relevant at this point as part of the discussion about
aspect ratio conversion techniques.
16:9 image padded top and bottom to fill 4:3
Blank
Visible region on 4:3 screen
Blank
Figure 11-4
Scanning an image.
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