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What method to use for detecting irregular black blobs?

asked 2017-08-14 02:17:31 -0500

PiMac gravatar image

Hi, I would like to detect if there is a black blob in a picture below (school project for detecting defects in fruits): image description

Right now I just detect if there is a circulat shape (houghcircles) and put 1 if there is and 0 if not - it isn't very accurate. I have to detect the black blobs but some of the blobs are false positive. I have been thinking about teaching an algorithm the good and bad pictures to get the best accuracy. I have only used knn for digit detection would it be a good choice to use it in this exercise? Can you suggest anything other to use?

Thank you!

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Where is the original image you're trying to process ?your circles change position ?

Ziri gravatar imageZiri ( 2017-08-14 03:59:16 -0500 )edit

My original image is just a plastic form with holes in it. You put fruits in it and backlight shines through them. I just cut out the holes and put them onto a black backgroud so it is easier to see the different holes. The placement is static so the holes are at the same places.

PiMac gravatar imagePiMac ( 2017-08-14 06:02:37 -0500 )edit

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answered 2017-08-14 04:05:21 -0500

Ziri gravatar image

updated 2017-08-14 04:06:49 -0500

  • Suggestion :

If you can detect circles position (or only one circle position ) you can create a predefined mask where Blobs are perfect (separate) white circle then detect holes using findContours and CV_RETR_CCOMP parameter .

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Thanks but since some of the blobs are false-positives I really would like someone to suggest a method that can be fed a learning set of images. I am not very advanced in such tasks but I will start with kNN classification algorithm and see how it goes.

PiMac gravatar imagePiMac ( 2017-08-14 06:06:59 -0500 )edit

SVM is better if you have small data. but the most important to increase accuracy is feature extraction method you'll be using for training.

Ziri gravatar imageZiri ( 2017-08-14 06:42:22 -0500 )edit

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Asked: 2017-08-14 02:17:31 -0500

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Last updated: Aug 14 '17