Capturing non-consecutive images using IMAQ 1394

[Ramkiran]

Hello,

Is there a way one can capture an image, for example once every 10, 20 or 30 frames depending on one's application? I am working on an application where I might not be able to see much of a change between a pair of consecutive image frames.  This being the case, using a "sequence" operation would result in unnecessary use of hard disc space.  I need to know if a command can be given to the VI requesting for an image once every 10, 20 or 30 frames depending on the application?

Thanks.

Ram

[Ramkiran]

Hi,

Regarding my last post, I just remembered that the "IMAQ1394 sequence.vi" has an option called "Skip Table" which the HELP window displays as reserved for future use.  I am not sure if this will work in getting images at desired frames.  I am going to give it a shot.

Thanks.

Ram

[BruceAmmons]

Acquiring and saving are two different things.  You may have to acquire 30 frames per second, but you can immediately drop 29 of those frames if you want.  Another option is just retrieving every Nth image from the firewire image buffer.  For example, set up the camera to take 30 frames per second, and set up a 60 frame buffer in continuous mode.  After starting the acquisition, just retrieve image 0, 30, 60, 90, etc. and you have one frame per second.  You might want to monitor the last frame acquired so you don't lock up the computer waiting for the next frame.

Another option:  Most firewire cameras have variable frame rates, and you can set them as low as 3 or 4 frames per second.  Then you only have to discard 3 out of 4 images.

Bruce

[JohannS]

Please not that the skip table option is not currently supported with IMAQ1394.