[Insight-users] Computing image spacing?

[Luis Ibanez]

Hi Motes,

The Magic is in

     Insight/Code/IO/itkImageIOBase.cxx

in the method:

void ImageIOBase::SetSpacing(unsigned int i, double spacing)

although... the magic is not that special.

The values are simply stored in the output image.

There is really not much to compute for the image spacing
when you are reading data from a file. You simply get this
from the file format and pass it to the image using the
SetSpacing() method above.

See the use of the SetSpacing() methods in any of the files:

Insight/Code/IO/

itkAnalyzeImageIO.cxx:924:
this->SetSpacing(dim,this->m_Hdr.dime.pixdim[dim+1]);
itkDICOMImageIO2.cxx:168:    this->SetSpacing(i, imageSpacing[i]);
itkGDCMImageIO.cxx:1981:  image.SetSpacing(0, m_Spacing[0] );
itkGDCMImageIO.cxx:1982:  image.SetSpacing(1, m_Spacing[1] );
itkGDCMImageIO.cxx:1983:  image.SetSpacing(2, m_Spacing[2] );
itkGE5ImageIO.cxx:532:    this->SetSpacing(2, distanceBetweenTwoSlices);
itkImageFileReader.txx:228:  output->SetSpacing( spacing );     // Set
the image spacing
itkImageFileWriter.txx:197:    m_ImageIO->SetSpacing(i,spacing[i]);
itkImageIOBase.cxx:132:void ImageIOBase::SetSpacing(unsigned int i,
double spacing)
itkImageIOBase.cxx:573:      this->SetSpacing(i, 1.0);
itkImageIOBase.h:115:   * SetSpacing() method is required when writing
the image. */
itkImageIOBase.h:116:  virtual void SetSpacing(unsigned int i, double spacing);
itkImageSeriesReader.txx:257:  output->SetSpacing( spacing );   // Set
the image spacing
itkImageSeriesWriter.txx:251:  outputImage->SetSpacing( spacing );
itkIPLCommonImageIO.cxx:367:  this->SetSpacing(0, m_ImageHeader->imageXres);
itkIPLCommonImageIO.cxx:368:  this->SetSpacing(1, m_ImageHeader->imageYres);
itkIPLCommonImageIO.cxx:369:  this->SetSpacing(2,
m_ImageHeader->sliceThickness + m_ImageHeader->sliceGap);
itkMetaImageIO.cxx:379:    this->SetSpacing(i,
m_MetaImage.ElementSpacing(i)*m_SubSamplingFactor);
itkNiftiImageIO.cxx:1187:      this->SetSpacing(6,this->m_NiftiImage->dw);
itkNiftiImageIO.cxx:1191:      this->SetSpacing(5,this->m_NiftiImage->dv);
itkNiftiImageIO.cxx:1195:      this->SetSpacing(4,this->m_NiftiImage->du);
itkNiftiImageIO.cxx:1198:
this->SetSpacing(3,this->m_NiftiImage->dt*timingscale);
itkNiftiImageIO.cxx:1201:
this->SetSpacing(2,this->m_NiftiImage->dz*spacingscale);
itkNiftiImageIO.cxx:1204:
this->SetSpacing(1,this->m_NiftiImage->dy*spacingscale);
itkNiftiImageIO.cxx:1207:
this->SetSpacing(0,this->m_NiftiImage->dx*spacingscale);
itkNrrdImageIO.cxx:437:        // this->SetSpacing(axii, 1.0);
itkNrrdImageIO.cxx:440:        this->SetSpacing(axii, spacing);
itkNrrdImageIO.cxx:467:          this->SetSpacing(axii, spacing);




    Regards,


            Luis


----------------------------------------------------------------------------
On Wed, Nov 25, 2009 at 11:42 AM, motes motes <mort.motes at gmail.com> wrote:
> How is the image spacing for a loaded image computed?
>
> I have tried debugging my way through:
>
> itkImageFileReader.txx
>
> but when I get to:
>
> template <class TOutputImage, class ConvertPixelTraits>
> void ImageFileReader<TOutputImage, ConvertPixelTraits>
> ::GenerateData()
> {
>
>  typename TOutputImage::Pointer output = this->GetOutput();
>
>
> output contains the spacing after returning from the "GetOutput()"
> call. But if I enter the GetOutput() call I never get to where the
> spacing are set. Does this happen in some other magic place?
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