Mirage 2000 User Manual page 8

Screen Aspect Ratio
to display a VCR output with a 4:3 aspect ratio onto a 10 foot (3m) high screen, the
width of the screen must be at least 13.3 feet (4m).
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Aspect ratio describes the proportion of the screen and is expressed as the ratio of
width to height, such as "4:3" or "5:4" (see right). Although image size and image
aspect ratio can both be adjusted quickly through projector software, it is still a good
idea to choose a screen aspect ratio which is most appropriate for your intended
applications. Ideally, to exactly fill a screen with an image, the aspect ratio of the
screen should correspond to the aspect ratio of the image, which depends on the
source in use. For example, standard video from a VCR has a 4:3 ratio
(approximately), whereas a high resolution graphics signal typically has a 5:4 aspect
ratio. By default, images from your projector will be as large as possible and, with
the exception of graphics sources, will maintain their aspect ratio.
NOTE: With a few exceptions, sources with less than 1280 x 1024 resolution have a
4:3 aspect ratio. The normal aspect ratio for 1280 x 1024 sources is 5:4.
Using a 5:4 Screen
With one exception, XGA images will—
by default—resize to fill an SXGA (5:4)
screen. The exception is that video signals
will retain their aspect ratio, as shown in
Figure 2.3. In this case, fill the screen by
increasing Vertical Stretch to slightly
expand the image to the top and bottom
edges of the screen. For details, see 3.6,
Adjusting the Image.
Using a 4:3 Screen
If you are using a 4:3 screen (but producing 5:4 images), images will—by default—
slightly overlap the screen vertically. To remedy, reduce Vertical Stretch so that the
"too tall" 5:4 image no longer spills over the top or bottom of the screen (Figure 2.4).
This control eliminates the need for simply moving the projector farther from the
screen, which would result in black borders for all sources. See 3.6, Adjusting the
Image.
NOTE: The Vertical Stretch adjustment may soften the image slightly, but is not
noticeable in most cases.
Figure 2.4. Using a 4:3 Screen for a mix of 5:4 and 4:3 sources
INSTALLATION & SETUP
Figure 2.3. Adjusting a 4:3 Video
Image
Mirage 2000/4000/6000 User's Manual
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