Hi,
Don't worry - that's fine and valid.
avwmaths++ is the replacement for ip but implements the same
algorithms.
Also, low-pass and high-pass are just special cases of band-pass
filtering. What is not possible at present is filtering with other
types of filters besides the single one implemented in avwmaths++
or ip.
All the best,
Mark
Pat Vee wrote:
>Mark,
>
>I'm confused, I have been using ip to low pass filter (e.g., ip_16SI -t,
>setting the hp_sigma = 0) - is this not a valid usage?
>
>Thanks,
>Pat
>
>On Tue, 28 Nov 2006 07:51:44 +0000, Mark Jenkinson <[log in to unmask]> wrote:
>
>
>
>>Dear Jason,
>>
>>I'm sorry but the bandpass filtering in avwmaths++ is our only
>>available temporal filtering option at the moment.
>>
>>You could stick with Matlab (using our i/o routines in
>>$FSLDIR/etc/matlab) or modify something like avwpspec to
>>output the real and imaginary parts of the fft and do
>>everything via multiplication in the frequency domain
>>(although you'll have to read and write separate the real
>>and imaginary components, and do the maths appropriately,
>>as complex data is not really supported except in
>>avwcomplex and prelude).
>>
>>Sorry we don't have a better solution at present.
>>
>>All the best,
>> Mark
>>
>>
>>On 27 Nov 2006, at 13:19, Alle Meije Wink wrote:
>>
>>
>>
>>>Hmm, don't know if there's a tool for that, sorry. Maybe you want the
>>>
>>>avwmaths++ -bptf
>>>
>>>option? I have never used it myself so cannot help you with it, but
>>>btpf stands for bandpass temporal filtering.
>>>
>>>From the help (which you get by just calling avwmaths++) it looks
>>>like a sharp cutoff in frequency. That gives you a temporal
>>>response which is quite smeared out.
>>>
>>>hth
>>>Alle Meije
>>>
>>>Jason Steffener wrote:
>>>
>>>
>>>>Hello. Thank you for the reply. I am interested in only temporal
>>>>filtering.
>>>>Yes the methods you describe all make sense. I do not need an
>>>>"ideal" filter
>>>>just an imporved one. By a higher-order (or higher-taps) filter I am
>>>>refering to one that will use more time points and have the
>>>>ability to
>>>>provide a sharper cutoff (a smaller transition band). And it is
>>>>this smaller
>>>>transition band that I am most interested in. I know that I can do
>>>>this in
>>>>MatLab easily enough. However, I am interested in streamlining
>>>>things so it
>>>>would be ideal to have an improved filter in FSL.
>>>>Thank you,
>>>>Jason.
>>>>
>>>>
>>=========================================================================
>>
>>
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