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One of the answers to this question : What is the best way to remove texture from a scanned textured photo paper? says to use ImageJ.

I have tried this on the sample photo and it doesn't work. I'm not familiar with ImageJ, so I'm obviously leaving something out. When I try to do inverse fft, it gives me the message: Frequency domain image required.

What am I missing? Thanks!

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    I just downloaded ImageJ and the picture in the question you linked to, tried following the instructions given in the answer and got a pretty nice-looking result. You might want to describe the exact steps you're using that lead to the message you get.
    – Ilmari Karonen
    Jun 18, 2014 at 19:55
  • Ps. I'm not sure if this is really an appropriate question for this site, but you could try discussing it in chat instead. Unfortunately, you normally need at least 20 rep points to talk in chat, but if you join this room I just created, I should be able to give you explicit talk access there.
    – Ilmari Karonen
    Jun 18, 2014 at 20:13
  • I think I know what caused the error you got, and I've posted an explanation below (and edited the original answer to hopefully eliminate this potential for confusion). However, now that the problem has been solved and the original answer clarified, I feel that this question should be closed (and eventually deleted), as it's essentially just extended commentary on the earlier answer.
    – Ilmari Karonen
    Jun 18, 2014 at 22:34
  • Please do not open a whole new question just to seek clarification on one of the answers to your other question. You should be able to comment on answers to your own question even as a new user I believe - if not it won't be hard to get the required reputation.
    – thomasrutter
    Jun 19, 2014 at 23:30

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I just downloaded ImageJ (actually, I installed it from the Ubuntu software centre) and the picture in the question you linked to, tried following the instructions given in the answer and got a pretty nice-looking result.

Here are the exact steps I followed:

  1. Start ImageJ.
  2. File -> Open..., select image to be fixed.
  3. Process -> FFT -> FFT
  4. Select pencil tool from the ImageJ toolbar window.
  5. Edit -> Options -> Line width..., set line width to 10. (A slightly larger value could probably have worked, too.)
  6. Use the pen tool in the FFT window to black out all the regularly spaced bright points (except the really big one in the middle).
  7. Process -> FFT -> Inverse FFT

...and that should do it.

Now, one thing to keep in mind is that, apparently, when you select an operation from the Process menu, ImageJ applies it to the image window that you last selected. If you try to use Process -> FFT -> Inverse FFT when you have a non-FFT image window selected, you will indeed get an error message saying "Frequency domain image required".

I suspect this is what went wrong when you tried this. Just try again, and this time make sure the FFT window is selected when you use the inverse FFT, and it should work.

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