Angle measurement by FFT

[Oky]

Dear ImageJ users,

I have been trying to measure orientation of fine lines in an image
utilizing FFT.

My idea can be summarized by following steps.
1. select a ROI for angle measurement (MFAmeasurement.jpg)
2. Run FFT (MFA-ROI.tif)
3. Find peak positions from the FFT result
4. Get angle and spacing information from the peak position in the FFT
result

I have confirmed that it is possible to apply my idea to get angle
measurement. It was very encouraging.

So I have made a very simple macro to do angle measurement automatically,
but I am stuck at step 4 because I don't know how to extract angle and
spacing information from the FFT result.

I could get intensity information not angle or spacing. In the manual for
FFT function in ImageJ I can read the information from the status bar of
ImageJ. However, I still could not find how to retrieve the angle and
spacing information in a macro.

Is there someone already has done this kind of measurement? Any advice
would be helpful for me to solve this issue.

Thank you very much for your kind advice in advance.
[image: Inline image 1]
Best regards,

Ohkyung Kwon

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[kirill8910]

Hello Ohkyung Kwon!

I had to deal with similar problem. I applied some contrast adjustments and thresholded the bright object so later using measure particles - the object had an angle in the table. Well maybe in my case situation on the fft image was a bit more distinguishable. But maybe if you apply some processing before fft as suggested before - you can get the better result!

Good luck

Kirill

[Prodanov Dimiter]

Hello,

May be what you are looking for is already implemented here:
http://bigwww.epfl.ch/demo/orientation/

You can get the histogram and that will be your raw orientation information.

Best regards,

Dimiter Prodanov

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[Oky]

I am sorry for this late reply for your valuable advice.

I had been trying to make the advice real, but caught up something else. So
I could not make no conclusive result for my case yet.

I hope I can deliver a news with some result in the near future.

Thank you very much for your valuable advice.


Best regards,
Ohkyung






On Mon, Mar 18, 2013 at 10:45 PM, Prodanov Dimiter <[hidden email]> wrote:

> Hello,
>
> May be what you are looking for is already implemented here:
> http://bigwww.epfl.ch/demo/orientation/
>
> You can get the histogram and that will be your raw orientation
> information.
>
> Best regards,
>
> Dimiter Prodanov
>
> --
> ImageJ mailing list: http://imagej.nih.gov/ij/list.html
>

... [show rest of quote]

--
Ohkyung Kwon

http://nicem.snu.ac.kr
http://www.linkedin.com/in/ohkyung
http://www.wpskorea.org

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