Re: How to Get 1D Power Spectra from 2D FFT Image

[Divakar Ramachandran]

Hi Dean,

I have tried out your modified radial profile plugin on the FFT of a HRTEM image from an amorphous carbon film. While the x axis in reciprocal nm units, when I use the point tool to click on peaks in the profile (with auto measure turned on), I get values that are really pixel units in the results window. I guess this is because the plot window is not a calibrated image. One way I would overcome this is to use Analyse - Set Scale, except I don't know how to set reciprocal units. Any suggestions how the pixel unnits can be converted to (1/nm) units?

Thanks,
Divakar



Dean Waldow Email Lists <[hidden email]> wrote: Hi Ben and Divakar,

Here is the link to a page a just put up on our server. It has my version of the radial profile and a class that I made for my OSX box.  You will likely need to make a new class. Let me know how it works.


http://www.chem.plu.edu/waldow/software.html


Dean





Divakar Ramachandran
Minneapolis, MN 55414, USA

 
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[Dean Waldow Email Lists]

HI Divakar,

> I have tried out your modified radial profile plugin on the FFT of  
> a HRTEM image from an amorphous carbon film. While the x axis in  
> reciprocal nm units, when I use the point tool to click on peaks in  
> the profile (with auto measure turned on), I get values that are  
> really pixel units in the results window. I guess this is because  
> the plot window is not a calibrated image. One way I would overcome  
> this is to use Analyse - Set Scale, except I don't know how to set  
> reciprocal units. Any suggestions how the pixel unnits can be  
> converted to (1/nm) units?

Hum... I think I follow your question. I usually save the data and  
work with it using IgorPro.  So, I have not worked with the resulting  
intensity versus wave vector image directly using imagej that much.  
It appears to me that the x,y values that change with the cursor are  
in the graph units but the imagej measurement values from say a point  
then the measure menu selections gives values as if the graph is an  
image not the data values from the graph.  I don't know a way around  
that aside from moving the data to another data analysis program.  
Others on the list may well know how to do this.  I usually list the  
values, copy, and then paste them in another program and that gives  
me the error and x/y values. Saving, I only have the x/y values being  
saved.

Not sure this helps any.

Dean
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