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Circle detection

asked 2018-08-29 12:47:37 -0500

tdon gravatar image

Hello,

I'm trying to find circles around the white disks (see example pictures below). The background is always darker than the foreground. The dots can sometimes be a bit damaged and therefore not of a full disk shape. Nevertheless I would like to fit circles as accurate as possible to the white disks. The found circles should all have a very similar radius (max. 5-10% difference). The circle detection should be focusing on determining the disks radius as accurate as possible.

What I tried so far: - Hough circle detection with various settings and preprocessing of the images - findContours

I was not able to produce satisfying results with these two algorithms. I guess it must have something to do how I preprocess the image but I have no idea where to start. Can anyone give me any advice for a setup that will solve this kind of problem?

Thank you very much in advance!

C:\fakepath\CC-T.jpg C:\fakepath\Laminat_X200_klein.tiff

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LBerger gravatar imageLBerger ( 2018-08-29 13:29:09 -0500 )edit

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answered 2018-08-30 07:07:08 -0500

Like @LBerger linked (but I do not really like links only responses) you should apply the following pipeline.

  • Binarize your image, using for example OTSU thresholding
  • Apply the distance transform to find the centers of all disk regions
  • Use those to apply a watershed segmentation

It will give you a result, like described in the tutorial and should look something like this:

image description

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answered 2018-08-31 02:32:03 -0500

Ziri gravatar image

I Suggest this method :

1 ) - as @StevenPuttemns suggested, use watershed or another method to get individual contours

2) - Use the circle fitting algorithm on each contour.

the other way is to predict circles using some kind of deep learning strategy...

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Asked: 2018-08-29 12:47:37 -0500

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Last updated: Aug 31 '18