Posted by
Herbie-4 on
Sep 23, 2014; 5:07pm
URL: http://imagej.273.s1.nabble.com/1D-Fourier-transform-in-macro-tp5009727p5009729.html
Ludovic,
where does the profile come from?
If it comes from an available image, then take the profile by an area
selection of one pixel height and crop the image to this line. Finally
take the FFT of this line image but take care that the "FFT Options" are
set "Raw power spectrum" & "Do forward transform". What you get is the
1D-Power spectrum of the line image that, of course, is smeared in
f_y-direction. (You may wish to consider the central line selection from
it.)
If the profile is given as numbers, then try to import them as text-image.
Be aware that the MTF is generally understood as the modulus of the
Fourier transform of the point-spread function. That said, you have to
take the square root of the power spectrum.
You may put together a macro by using the macro recorder.
HTH
Herbie
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On 23.09.14 16:36, Ludovic Pinier wrote:
> Hi everyone,
>
> I would like to perform a Fourier transform on a profile, and nest it
> in an ImageJ macro. I already saw that it is quite new (July 2014)
> that 1D transform is more easily accessible through FHT.transform1D I
> am OK with the macro built-in commands, but not with more
> sophisticated things.
>
> Does anyone has an example how to nest such function in a macro?
>
> This is to perform direct MTF evaluation from the profile
> (resolution), because my targets are circular and I can't use the
> slanted edge method provided in already existing plugins.
>
> Best regards, Ludovic
>
> -- ImageJ mailing list:
http://imagej.nih.gov/ij/list.html>
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