[Insight-users] Analytic signal

[Renaud Isabelle]

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




		
---------------------------------
 Appel audio GRATUIT partout dans le monde avec le nouveau Yahoo! Messenger
 Téléchargez le ici !  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://public.kitware.com/pipermail/insight-users/attachments/20050714/cfd4dbc0/attachment.html