how to identify the periodic pattern in a given image ?

I have a image which has periodic pattern in it. I want to retrieve the periodic pattern and display it.

I am following this procedure.

1. Apply fft for the image.
2. Identify the periodic frequency by using magnitude and phase spectrum
3. Design a band pass filter with the periodic frequency
4. Multiply the image with the designed filter
5. Apply ifft for the output.

But i am not sure how to identify the periodic frequency from the spectrum ??

Answer 1

[Image Analyst]

It will be the spikes/peaks. See my demo.

[vinod kumar]

why you are adding ripples to the image ?? Alreday a periodic pattern is there in the image ??

[Image Analyst]

The demo took an uncorrupted image (no periodic pattern yet), and added periodic noise (ripples) to it. For you, this would be the starting image. Then it found the spectrum of the ripples, erased them in the spectral domain, and inverse transformed to produce an image with ripples removed (or almost removed). If you want, you can post your image.

[vinod kumar]

</matlabcentral/answers/uploaded_files/18911/input.jpg> This is my input image

[vinod kumar]

</matlabcentral/answers/uploaded_files/18912/periodicpattern.jpg> This is my periodic pattern