Editing the FFT of a jpeg

Posted by Robby Connor on
URL: http://imagej.273.s1.nabble.com/Editing-the-FFT-of-a-jpeg-tp3691067.html

I am trying to load an jpeg into ImageJ and run an FFT on it to edit out a
known pattern I have.  The problem I am having is after I edit the
transformed image and inverse FFT nothing has changed.  I can tell my edit
has no effect because I can black out the entire frequency-domain picture
and run an inverse FFT on it, which will result in my exact same original
picture.  

The weirdest thing about this is that it actually worked for about 2 days on
one of my computers, then stopped working (it never worked on the other
computer).  When it was working, here were my steps:
1)convert to 8-bit black and white under Image>>Type.
2)change my editing background paint color to black.
3)run the Process>>FFT>>FFT on the picture.
4)select circular areas on the transformed picture relating to the
frequencies of the grid pattern of the original, then press backspace.  This
deleted the area and left a black color due to step 2).
5)run the Process>>FFT>>Inverse FFT.

This had been working, then spontaneously stopped working.  I had been
trying to check if any settings were different from the computer whose
ImageJ Inverse FFT worked to the one that didn't, so I could've accidentally
changed something critical.  

MAIN QUESTION:
How do I get this feature to work again?

SECONDARY QUESTION:
Is there any other program (or an add-on to ImageJ) that anybody knows about
that would do this process for me?

EXTRA INFO:
I run XP on both computers.