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Circle detection

asked 2018-08-29 12:47:37 -0600

tdon gravatar image


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 -0600 )edit

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answered 2018-08-30 07:07:08 -0600

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 -0600

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 -0600

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Last updated: Aug 31 '18