Display images at video rate

[Rami_Y]

Hello
I have NI PCI 1424 board and the NI PCI 1422 board. I a trying to acquire images from my custom imager and display them at a video rate. I am using IMAQ Acquire Grab as shown in one of the examples provided with LabVIEW. I am grabbing one frame at a time and looping infinitely so that I can get a continuous stream of frames. This is doing the job of displaying the images but I know I am not getting the full frame rate out of my sensor and it is tending to be rather slow (about 1-2 frames per second).

I am sure there would be other ways to do this. I just do not know how.
Any ideas?
Thanks

[Scott_R]

Hello,

Have you tried implementing the ring example? There is a LabVIEW shipping example called LL Ring.vi that makes use of multiple buffers. This should improve the frame rate that you are able to achieve. You can find this example by browsing to C:\Program Files\National Instruments\LabVIEW 7.1\examples\IMAQ\IMAQ Low Level.llb.

Try that example and let me know if you have any additional questions on this issue.

Regards,
Scott R.
Applications Engineer
National Instruments

[Rami_Y]

Thank you for the suggestion. It is indeed a much faster display of images.

I do have another beginner question though.

Is there a way for me to find out what is the frame rate being displayed? I know the frame rate is shown in the Measurement and Automation Explorer in the grab mode. Is there a way to find out the frame rate within LabVIEW? In the LL Ring.vi example, can I use the number of buffers as an indicator of the number of frames? Is each buffer a new frame?


Thank you very much.

[Dan_Quinn]

Rami,

The way you are monitoring frames is fine, however you may also want to try using an IMAQ property Node. You can find this on the Image Acquisition Functions Pelette and once it is connected to an IMAQ Session in, you can select the property Status Information >> Frame Count and read out how many frames you are acquiring from there. Hopefully this helps. Let us know how things work out!

Regards

Dan
National Instruments

[Rami_Y]

Hello Dan,
Thank you for your tip.

I tried to include the Frame Count property in my application. However, when I hit run, the application does not work and when I stop it, an error comes up saying that the selected property could not read. This is a custom made sensor and a driver that I've written, so I do not know if there is something I would have to do to include this feature in my driver.

Thank you very much.
Rami

[Dan_Quinn]

Rami,

Since the Frames Read property is part of the IMAQ driver, it is understandable why it is not working with your custom camera and custom driver. I would highly suggest incorporating this functionality into your driver where you are counting the number of times your frame valid signal pulses.

Regards

Dan
National Instruments

[Rami_Y]

Hello,

I was wandering if you know a driver that ships with NI that has the Frame counter property included in it, or if you could show me the syntax to include that property in my driver.
That would be awesome.

Thank you very much,
Rami

[nipun]

Hello Rami,

I have modified the LL Ring example to include frame rate estimation and attached that with this email. You will need LabVIEW 7.1 to open this example. I hope this helps you out. Have a nice day!

Regards,
Nipun M
Applications Engineer
National Instruments