# finding axis of symmetry in an image

edit after 5 years:

i marked Michael Burdinov's answer as the best answer. Because i have not got any answer better than his answer yet.feel free to give a better answer if you have.

Given an image containing a mirror symmetrical object, such as a car or a butterfly, I want to find the symmetry axis:

Due to perspective distortions the two halves of a symmetrical object will never match exactly. The background and noise further complicate things.

But given the assumption that the image of the object is mostly mirror symmetric and takes up a large portion of the picture, it should be possible to find a best fit for the axis of symmetry.

How can I find this axis?

I tried flipping the input image, then executing SURF and FindHomography on the original and the flipped image, but the results are very poor, and not robust at all.

Is there a better way?

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( 2017-10-04 08:58:56 -0500 )edit

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Symetry detection in real images is quite difficult task. Plenty of algorithms were proposed for it, but no one is simple. Google "image symmetry detection" if you want to see some papers in this field.

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i vote keeping this answer with -1. it will be an example of beautiful answers that have not been appreciated

( 2017-09-08 12:50:44 -0500 )edit

@sturkmen, correct me if wrong, but reactivating questions from 2012 which do not have a clear solution like this one, seems kind of ridiculous right?

( 2017-09-09 04:33:52 -0500 )edit

i wanted to think (search) about a solution. just wanted to reactivate the question and wait is there any new answer. indeed @Ziri led some light.

( 2017-09-09 04:55:04 -0500 )edit

(Suggestion) - If you can find object contour data points applying PCA allows you to find centroid and 2 principal vectors of your data points.

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Asked: 2012-10-09 15:11:51 -0500

Seen: 2,749 times

Last updated: Sep 08 '17