# 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?

Symmetry challenges