[Insight-users] Problem with Multiplying Two Complex Images, and a big thanks to ITK community for this extensive body of work!

[Saurabh Sethi]

Hi Dan,
Many thanks for this info.
I had a brief look at this already.
Just that I have 3D images of average size 3000 * 1800 * 15, that
convolution becomes almost a no show.

Regards

Saurabh



On Mon, Nov 24, 2008 at 12:54 PM, Dan Mueller <dan.muel at gmail.com> wrote:

> Hi Saurabh,
>
> Welcome to ITK!
>
> I can't respond regarding your FFT issues/questions, however if your
> convolution kernels are small (or computation time is not an issue)
> then you may consider computing the convolution directly.
>
> Section 11.4 of the ITK Software Guide describes how to do this using
> neighborhood iterators. This part of the software guide is generated
> from:
>    Examples\Iterators\NeighborhoodIterators4.cxx
>
> HTH
>
> Regards, Dan
>
> 2008/11/24 Saurabh Sethi <sethi.saurabh at gmail.com>:
> > Hi All,
> >
> > I recently started using the ITK after a lot of word of mouth publicity
> from
> > peer groups :)
> >
> > And I must say that im very impressed by it.
> >
> > Have been going through all of the Software guide and Message Archives
> since
> > some time now.
> >
> > I have a bit of problem with the FFT / IFFT implementation. There is some
> > "Access Violation" that I'm unable to fix since some time.
> >
> > Maybe I have used the Complex Image in a wrong ( read Silly) way which
> I'm
> > unable to debug now.
> >
> > It would be great if someone could help ->
> >
> >
> >
> > I need to convolve two images (one is the test image, and other is my
> data
> > image)
> >
> > For this, I had thought of first doing the FFT, then Multiplying both the
> > images and taking the IFFT in the end.
> >
> >
> >
> > Here is my pseudo code:
> >
> >
> >
> > read image 1 (im1)
> >
> > Padd the image to nearest power of 2.
> >
> > compute its FFT. (I'm using FFTRealToComplexConjugateImageFilter)
> >
> >
> >
> > read image 2. (im2)
> >
> > Padd the image to the same power of 2.
> >
> > compute its FFT.
> >
> >
> >
> > Multiply both the images
> >
> > MultiplyImageFilter->SetInput1(fft_input);
> >
> > MultiplyImageFilter->SetInput2(fft_weight);
> >
> > MultiplyImageFilter->Update();
> >
> >
> >
> > IT is here that this strange error occurs:
> >
> >
> >
> > Unhandled exception at 0x0046193a in ItkScatter.exe: 0xC0000005: Access
> > violation reading location 0x61371000.
> >
> >
> >
> > And the code breaks in at this place  in file
> > itkDefaultPixelAccessorFunctor.h:
> >
> > inline const ExternalPixelType Get( const InternalPixelType & input )
> const
> >
> > {
> >
> >    return m_PixelAccessor.Get( input );
> >
> > }
> >
> >
> >
> >
> >
> > Below is the relevant part of the code:
> >
> >
> >
> > typedef itk::FFTRealToComplexConjugateImageFilter<pixelTypeC, dim2D>
> > FFTFilterType;
> >
> > typedef itk::FFTComplexConjugateToRealImageFilter<pixelTypeC, dim2D>
> > IFFTFilterType;
> >
> > typedef FFTFilterType::OutputImageType ComplexImageType;
> >
> > typedef itk::MultiplyImageFilter<ComplexImageType, ComplexImageType,
> > ComplexImageType>MultiplyImageFilterType;//>
> >
> >
> >
> > constPadImage->SetPadLowerBound(paddin);// specifying padding options
> >
> > constPadImage->SetPadUpperBound(paddin);
> >
> > constPadImage->SetInput(inputImage_C); // set padding filter input.
> >
> > fftFilter->SetInput(constPadImage->GetOutput()); //set the fft.
> >
> > ComplexImageType::Pointer fft_input = fftFilter->GetOutput(); // fft
> filter
> > done on image.
> >
> > fftFilter->Update();
> >
> >
> >
> > constPadImage2->SetPadUpperBound(paddin_wt_upper);
> >
> > constPadImage2->SetInput(inputImage2); // set padding filter input.
> >
> > fft_wtFilter->SetInput(constPadImage2->GetOutput()); //set the fft.
> >
> > ComplexImageType::Pointer fft_weight= fft_wtFilter->GetOutput();// fft
> > filter done on image.
> >
> > fft_wtFilter->Update();
> >
> >
> >
> > MultiplyImageFilter->SetInput1(fft_input);
> >
> > MultiplyImageFilter->SetInput2(fft_weight);
> >
> > MultiplyImageFilter->Update() // Error occurs here.
> >
> > ifftFilter->SetInput(MultiplyImageFilter->GetOutput());
> >
> > ifftFilter->Update();
> >
> >
> >
> > Hi,Many thanks
> >
> > Saurabh
> >
> > New ITKer..
> >
> >
> >
> >
> >
> > 2008/11/21 chensiqi <pidanchen at hotmail.com>
> >>
> >>
> >> Hi, ITKers,
> >>
> >> Does anybody know how to load sequence items using ITK? Such as "ROI
> >> Contour Sequence".
> >> Or if you know how to do it in GDCM, and integrate into ITK, that will
> >> also be very helpful.
> >>
> >> Thanks
> >> Siqi
> >>
> >>
> >> ________________________________
> >> 更多热辣资讯尽在新版MSN首页！ 立刻访问！
> >> _______________________________________________
> >> Insight-users mailing list
> >> Insight-users at itk.org
> >> http://www.itk.org/mailman/listinfo/insight-users
> >>
> >
> >
> > _______________________________________________
> > Insight-users mailing list
> > Insight-users at itk.org
> > http://www.itk.org/mailman/listinfo/insight-users
> >
> >
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.itk.org/pipermail/insight-users/attachments/20081124/fd191f32/attachment.htm>