Image processing using lab view

[jaiganesh]

hi
I am trying to find the centriod of a image using lab view.I was able to the same using the vision builder software.but i want to do it using lab view so that it can be interfaced along with other applications.do i need any additional modules to do that??.The image is to be acquired by using a camera.
thank you

[mhaag]

Thank you for contacting National Instruments. The IMAQ Vision for LabVIEW module includes most of the processing and analysis tools that will be used in LabVIEW for examining images. If you have the Vision Development Module (or just Vision on your system), then you will have an IMAQ Centroid VI available. This VI computes the center of the energy of an image or of a portion of an image and sounds like the function you need for your application.

If you are not sure if you have Vision installed on your computer, then you can check this through Measurement & Automation Explorer (MAX). Once you open MAX, expand the Software folder located in the left pane. This will list all of the National Instrument's software installed on your computer, and, by clicking through t
he various applications, you can see what version you have as well.

For more information on the LabVIEW Vision Development Module, please refer to the following website:

http://sine.ni.com/apps/we/nioc.vp?cid=1396〈=US

Regards,
Michael
Applications Engineer
National Instruments

[Mike Lee]

Quick question...

Is the IMAQ centriod VI described here doing the same thing as what any of these VI's are doing?

http://forums.ni.com/t5/LabVIEW/Centroid-of-an-2D-Array/m-p/1136618#M500884

Mike

[Mike Lee]

Ok, I'm convinced the IMAQ Centriod VI, isn't doing that centre of mass calculation above. I compared the results whilst inputting a 2D Gaussian, and they did not match as the distibution moved to the edge of the range.

If anyone has any idea what the IMAQ VI is doing, I'd be much appreciative.

Mike

[Andrey_Dmitriev]

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@Mike Lee wrote:

If anyone has any idea what the IMAQ VI is doing, I'd be much appreciative.

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IMAQ Centroid VI doing something like that:

Andrey.

[Mike Lee]

I think I'm right in saying that the IMAQ centriod VI is binary. i.e. if the intensity in a particular region is above the threshold, it returns a 1. It then finds the geometric centre of 1's.

So this may be ok for smoothly varying images, but worth noting. The Vi Andrey posted weights every region according to its intensity.

[Andrey_Dmitriev]

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@Mike Lee wrote:

I think I'm right in saying that the IMAQ centriod VI is binary. i.e. if the intensity in a particular region is above the threshold, it returns a 1. It then finds the geometric centre of 1's.

So this may be ok for smoothly varying images, but worth noting. The Vi Andrey posted weights every region according to its intensity.

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IMAQ Centroid is not "binary". The code provided by me above deliver exactly the same result as IMAQ Centroid VI.

Andrey.

[Mike Lee]

What threshold values have you set for the IMAQ centriod? I found if I lowered the threshold to zero, the calculation returned the centre of the image regardless of what I input, consistent with each pixel being the same value. The differences only show up otherwise as you move the centre of mass to the edge of the image. I'm using LabVIEW 8.6 so maybe your version isn't binary. I've attach my programmes.

[Andrey_Dmitriev]

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@Mike Lee wrote:

What threshold values have you set for the IMAQ centriod?

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There are no "threshold values" for IMAQ Centroid available. This VI requires Input Image and optional Mask. That is all. LV 2010 + Vision 2010.

[Mike Lee]

Thanks for you're reply, I now see that I'd set a threshold on the image earlier in the program which replaced thresholded values with a constant....