comparing images from two different sources, (one from PC and other from a frame capture )

[vik_tech]

Hey,
         I am using NI Vision for pattern matching. What I am doing is comparing two images from two different sources. My 1st source is capturing a TV frame using some hardware which I have. For eg, say I capture the ESPN or DISNEY kids logo from TV. Let's call this image A
          My 2nd image is a BMP file where I copied the DISNEY or ESPN Logo(from the website). Let's call this Image B.  To the naked eye the images look pretty much the same. What's the best way to find the logo from image B to A. I am using the Pattern matching Example VI  where I force it to learn the template from B and then search for it in A. i had no luck at all. Pattern matches from the same source  is at 99% Confidence level while from different sources less than 20 %. To the naked eye both images are the same.  So I am wondering do I need to do some manipulation? Both images are bmp files.
        I am new to NI vision and would appreciate any help.
Thanks
Bhavik

[Brandon M]

Hi Bhavik,

It sounds like the problem is that the template image differs too much from the framegrabber image.  You should snap am image from the framegrabber and do any necessary image manipulation with photo-editing software, such as cropping and background cleanup.  Then, you can use this image as a template and you should have a much higher success rate matching the pattern.

[vik1]

Brandon,

              Thanks for replying. I tried elongating the image and it worked. My frame image is 640 * 480 pixels while the PC image is 705 * 480. Once I extended the frame image to 705 * 480 it started working. I guess my question to you is there any VI that will let me do that instead of using paint. I have never played with images before so I don't really know.

thanks

bhavik

[Brandon M]

Hi Bhavik,

If you are wanting to stretch an image, you can do that with the IMAQ Resample VI.  You just need to wire an input image and a desired height and width.  However, I still think that you will have better accuracy if you can do a capture of the on-screen logo to match and clear the background.

Either method should work with reasonable accuracy.  Let me know if you have any further questions.

[vik1]

Brandon,

               hi! Do you mind if I email you the images directly? We are trying to evaluate whether to buy NI Vision for our company and want to have a proof of concept in place as soon as possible. I am a bit inexperienced when it comes to images. We contacted one sales engineer last week. He promised to look into it but we are unable to reach him this week. I guess he's busy. Can you give me you email id ? The logo now matches 90% but we are interested in some other details too which as of now match only 50%.

Thanks

Bhavik.

[GuenterMueller]

Hi Bhavik.
You should not hesitate to buy NI Vision.
It's features in LabVIEW are excellent. Especially I do not want to miss the debugging capabilities.
The prices of Vision libraries from different vendors with professional support are similar.
So if you already use and like LabVIEW -> stay with Vision from NI.
(And finally, consider this forum in case you face some vision trouble.)
Have a great day, Guenter (no NI employee, by the way)

[Brandon M]

Hi Bhavik,

If you need a proof-of-concept, you should try contacting the field engineer again.  I can also help to get you pointed in the right direction if you post a sample image and a description of what you are wanting to do.  If the images are proprietary, you can post a similar image that needs to be manipulated, and we can get started with that.