Data Translation DT3153, Руководство пользователя

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Principles of Operation
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Passthru Scaling
Using software, the DT3153 board can scale the passthru image to the
height and width that most closely match the requested size. Unlike
hardware scaling (see
page 18 ), where the hardware scales the image
before the image is transferred to system memory, passthru scaling is
done in software after the image is transferred to system memory.
Values for the width range from 4 to 640 pixels (the default) for 60 Hz
image formats or from 4 to 768 pixels (the default) for 50 Hz image
formats (in increments of 4). Values for the height range from 1 to 480
lines (the default) for 60 Hz image formats or 1 to 576 lines (the
default) for 50 Hz image formats (in increments of 1).
Overlays
Using software, you can add overlays to the display when capturing
images. Overlays are a means by which you can place an image on
top of another image that was captured using passthru.
Note: Overlays require Direct Draw Interface (DDI) support.