National Instruments IMAQTM Benutzerhandbuch

After you create an image, you can acquire an image into the imaging 
system in one of the following three ways:

•

Acquire an image with a camera through the image acquisition device.

•

Load an image from a file stored on the computer.

•

Convert the data stored in a 2D array to an image. 

Methods that acquire images, load images from file, or convert data 
from a 2D array automatically allocate the memory space required to 
accommodate the image data.

Use the CWIMAQ control to acquire images with a National Instruments 
IMAQ device. You can use IMAQ Vision for Visual Basic to perform 
one-shot and continuous acquisitions. You can choose the acquisition type 
during design time by setting the value of the Acquisition Type combo box 
to One-Shot or Continuous. The Acquisition Type combo box is located 
on the Acquisition property page of the CWIMAQ control. You can set the 
value at run-time by setting the 

CWIMAQ.AcquisitionType

 property to 

cwimaqAcquisitionOneShot

 or 

cwimaqAcquisitionContinuous

.

Use a one-shot acquisition to start an acquisition, perform the acquisition, 
and stop the acquisition using a single method. The number of frames 
acquired is equal to the number of images in the images collection. Use the 

CWIMAQ.AcquireImage

 method to perform this operation synchronously. 

Use the 

CWIMAQ.Start

 method to perform this operation asynchronously. 

For information about synchronous and asynchronous acquisitions, refer to 
the NI-IMAQ User Manual.

If you want to acquire a single field or frame into a buffer, set the image 
count to 1. This operation is also referred to as a 

. Use a snap for 

low-speed or single capture applications. The following code illustrates a 
synchronous snap:

Private Sub Start_Click()

CWIMAQ1.AcquisitionType = cwimaqAcquisitionOneShot

CWIMAQ1.AcquireImage

End Sub