User`s guide

7 Working with Acquired Image Data

7-8

In addition, configure a large enough acquisition to allow several calls to peekdata

before it finishes.

vid.FramesPerTrigger = 300;

Start the image acquisition object — Call the start function to start the image

acquisition object.

start(vid)

The video object is now running but not logging.

isrunning(vid)

ans =

islogging(vid)

ans =

Use peekdata to view frames before a trigger — If you call peekdata before

you trigger the acquisition, peekdata can only return a single frame of data because

data logging has not been initiated and the memory buffer is empty. If more than one

frame is requested, peekdata issues a warning that it is returning fewer than the

requested number of frames.

pdata = peekdata(vid,50);

Warning: PEEKDATA could not return all the frames requested.

Verify that peekdata returned a single frame. A single frame of data should have

the same width and height as specified by the ROIPosition property and the same

number of bands, as specified by the NumberOfBands property. In this example, the

video format of the data is RGB so the value of the NumberOfBands property is 3.

whos

Name Size Bytes Class

pdata 96x128x3 36864 uint8 array

vid 1x1 1060 videoinput object