[Insight-users] FFT

[Renaud Isabelle]

Hi again, 
 
Does anyone know how to retrieve each ligne of a 2D image, compute the FFT 1D on it, and this for all my image? 
 
it seems to be very simple but I'm not familiar with ITK, iterators, FFT so I'm really lost in all of this.
 
Isabelle

Renaud Isabelle <renauisa at yahoo.fr> a écrit :
Hi guys,
 
I have to display the enveloppe of my raw images, by computing absolute value of its analytic signal. 
 
To compute the analytic signal of my input image, I know that all I have to do is to compute the fourier transform of my input image by itk FFT function and to ``zeroise`` the result for negative frequencies. Then, I just need to return to space domain with iFFT function. Great! It seems very simple. 
 
But if I compute FFT of my signal, all I have will be data. I don't know which ones correspond to negative frequencies. How could I know? I need to compute FFT of my signal and then sort out my result data according to negative and positive result. 
 
I am a bit confused about that. Does anyone have an idea to suggest me?
 
Isabelle





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