Chapter 2
Hardware Overview
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National Instruments Corporation
2-5
Acquisition Window Control
You can configure numerous parameters on the NI 1424 to control the
video acquisition window. A brief description of each parameter follows:
•
Acquisition window
—The NI 1424 allows the user to specify a
particular region of active pixels and active lines within the incoming
video data. The active pixel region selects the starting pixel and
number of pixels to be acquired relative to the assertion edge of the
horizontal (or line) enable signal from the camera. The active line
region selects the starting line and number of lines to be acquired
relative to the assertion edge of the vertical (or frame) enable signal.
•
Region of interest
—
The NI 1424 uses a second level of active pixel
and active line regions for selecting a region of interest. When you
disable the region-of-interest circuitry, the device stores the entire
acquisition window in onboard or system memory. However, when
you enable the region-of-interest circuitry, the device acquires only
a selected subset of the image frame.
•
Interlaced video
—The NI 1424 supports both interlaced and
non-interlaced, or progressive scan, digital video signals. In
interlaced mode, the NI 1424 combines the odd and even fields
into one contiguous frame for analysis. In non-interlaced mode,
each field is treated as an independent frame.
