Flickering/jumpy image out

[bluefocs]

I have design this labview VI to constantly get image from a camera, do some analysis on it and display it at different stages. But the images I get are flickery and often don't display the correct thing.

Is there a way of fixing this?

I have attached my VI

[Andrew McL]

Hi bluefocs,

Thank you for contacting National Instruments. I am not sure why you are getting this problem with your acquisition. One idea that occurs would be to reduce the delay you have in your loop. I would suggest making it as small as possible just to see if that is causing the jitter that you are seeing. 

Could you also provide a little more detail about which camera you are using and how this jitter is manifesting?

Many thanks,

[bluefocs]

I am using a PCI NI-1405 framegraber board with a non-NI camera, not sure what make it is but has "Elmo" written on the side.

The bigger problem is that I have three image outs, and they display the wrong image, for example my image out labeled 'Orginal Image' flicks between displaying the orginal image and the images at all the other stages of processing. The other two image outs simply display the final image, but occasionally turn to a black.

I am pretty sure its a labview coding problem rather than the camera hardware, works fine in Vision Builder, other Labview VIs, etc.

[Andrew McL]

Hi Bluefocs,

I've managed to run your VI but I'm a little unclear of what you are actually trying to do with your application. As an initial guess, are you trying to XOR/AND your acquired image with an image you had saved before?

Could you possibly provide a detailed explanation of what you are trying to do and I shall try and help you out.

Many thanks,

[bluefocs]

That's pretty much it, it does an XOR function on an image I have saved previously.

The VI is to detect water droplets, I take a picture without the water droplets infront of lined background using vision builder then comapare it to the image from the camera. So any change in image will give a high (white). The other VIs get rid of smaller particles plus a few other things. 

I plan now to do particle analysis on the image i get.

I want to also so what the image is like at each stage at each stage of processing, as it takes a while to align the camera with my lined background (I often need to take a new picture to compare it with, then i need to be very careful not to touch the camera!).

Hope this helps.

[Andrew McL]

Hi bluefocs,

I think one of the first things I would do would be to remove some of the setup to outside the while loop. I would strongly recommend converting your express VIs into standard VIs as I think they may affect the preformance of your VI. I've attached an article which explains the fundamentals of how to go about developing applications using IMAQ and some common workarounds.

http://zone.ni.com/devzone/cda/tut/p/id/4538

http://digital.ni.com/public.nsf/allkb/B6258C0AE767659D86256F3900578F6A?OpenDocument

If you do this, you may find the flickering is removed.

Many thanks,