[Insight-developers] Consistency in the output of forward/inverse FFT image filters

[Cory Quammen]

Gaetan,

Do you have any ideas for neat tricks to figure out what the full
dimension of the transformed image should be given the half image? The
problem is that an image with size n (n even) yields a half image that
is the same size as the half image produced for an image with size
n+1.

Currently, the FFT filters have a flag ActualXDimensionIsOdd that is
used to resolve this ambiguity. It would be fantastic if users didn't
have to set this to get the correct behavior. I haven't yet thought of
a way to figure out the full image size automatically, and Googling
hasn't revealed anything.

Thanks,
Cory

On Fri, Aug 19, 2011 at 11:10 AM, Cory Quammen <cquammen at cs.unc.edu> wrote:
> [snip]
>>>
>>> That's a good suggestion that would simplify things. Are you proposing
>>> to make the VNL FFT filter always produce a half output image for real
>>> inputs?
>>
>> That's what I'm proposing.
>> It may have a cost for vnl filters, but hopefully it will be compensated by
>> the lower amount of memory required for further transformations in the
>> frequency domain.
>
> Okay, sounds good to me. I'll get to work on implementing this.
>
> Cory
>
> --
> Cory Quammen
> Research Associate
> Department of Computer Science
> The University of North Carolina at Chapel Hill
>



-- 
Cory Quammen
Research Associate
Department of Computer Science
The University of North Carolina at Chapel Hill