detecting parallel lines in an image using Frequency domain

Question

I have an image with straight lines. I want to check if the lines are parallels using frequency domain. I\'m doing fft on the image and i get the transform image.

Do

Answer 1

So here are the two cases, using either some random angle or the same angle, of 2 lines of variable lengths, and their absolute value ffts.

So there are many ways you can tell if they are parallel or not by looking on their fft, I'll give a hint in one of the easier directions, start from the center of the fft'ed image...