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Chapter 4 Using NI-IMAQ for IEEE 1394 Cameras in LabVIEW
© National Instruments Corporation 4-3 NI-IMAQ for IEEE 1394 Cameras User Manual
Image Buffer
Many acquisition VIs require an image buffer to receive the captured
image. You can create this image buffer with IMAQ Create. Refer to the
Buffer Management section of this chapter for more information about
using buffers. Image In receives the image buffer. Image Out returns the
captured image.
Region of Interest
The acquisition VIs use the Region of Interest input to specify a
rectangular portion of an image frame to be captured. You can use Region
of Interest to reduce the size of the image you want to capture. Region of
Interest is an array of four elements whose elements are defined as Left,
Top, Right, and Bottom. If Region of Interest is not wired, the entire
image acquisition window is captured. Configure the default acquisition
window using MAX.
Acquisition VIs
Two types of acquisition VIs are available in LabVIEW: high-level and
low-level.
High-Level
Use the high-level acquisition VIs for basic image acquisition applications.
VIs are included for snap, grab, and sequence, as described in the
Acquisition Types section of this chapter.
Low-Level
Use the low-level acquisition VIs for more advanced image acquisition
applications. The low-level VIs configure an acquisition, start an
acquisition, retrieve the acquired images, and stop an acquisition. You can
use these VIs to construct advanced IMAQ applications.
Complete the following general steps to perform a low-level acquisition.
1. Call IMAQ1394 Init to initialize the board and create an IMAQ1394
Session.
2. Call IMAQ1394 Configure Acquisition to allocate resources for the
acquisition.
3. Call IMAQ1394 Start Acquisition to start transferring data from the
camera.