[Insight-users] Q: Approaches for convolution with a general kernel

[Luis Ibanez]

Hi Stefan,

A convolution kernel of 40x40 is actually quite large.


You should definitely consider your second option of
using filtering in the Fourier domain.


You will find an example on the use of the FFT filters
available in ITK into the directory:

        Insight/
             Examples/
                   Filtering/
                       FFTImageFilter.cxx

If performance at run time is a concern, you should
also install the FFTW library in your system.

Otherwise, ITK will use the FFT available from VNL.



Regards,


      Luis



------------------------
Stefan wrote:

> I have implemented convolution with a general kernel with other tools 
> but I'd like to try this out using ITK, but I am new to the toolkit and 
> a little lost in the many concepts. A high-level suggestion of 
> approaches for this problem would be appreciated...
> 
> I have a relatively small-sized 2D kernel (no more than 40x40 pixels) 
> that I want to use for convolution with images of about 1000x1000 
> pixels. I can either calculate this by brute force or do the convolution 
> in Fourier transform space. I do not find a lot of references to this 
> problem in the documentation, but it seems like a common enough problem 
> that I must have missed something. My current plan is to work from the 
> Sobel edge-detection code and develop a direct-calculation routine from 
> that. Any suggestions for alternative places to start?
> 
> Thanks in advance,
> 
> Stefan Engstrom
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