[Insight-developers] ITK_Origin + MetaDataDictionaryArray + GDCM2

[Daniele E. Domenichelli]

2009/10/3 Mathieu Malaterre <mathieu.malaterre at gmail.com>:
>> Using GDCM 1 user can set origin of the image adding to the
>> MetaDataDictionaryArray the entry (0020|0037) because there is a check:


Sorry... this is a typo, should be  (0020|0032)


>> <from itkGDCMImageIO.cxx>
>>
>>  if( !header->GetValEntry(0x0020,0x0032 ) )
>>   {
>>   [write origin in str]
>>   header->InsertValEntry(str.str(),0x0020,0x0032);
>>   }
>>
>>
>> Using GDCM 2 origin are calculated and tags are created by gdcm::image
>
> I did not quite follow your bug description. What I'd like to know is:
> Is there is a difference in behavior in between GDCM 1.x and GDCM 2.x


Yes, there is a difference, but now I'm not sure if this is a bug in
ITK or in GDCM... I'll try to explain better:

GDCM 1) Setting tag (0020|0032), this tag is attached in the produced DICOM
GDCM 2) Tag (0020|0032) is discarded due to this:


----

<from itkGDCMImageIO.cxx>
1328 #ifdef GDCM_MAJOR_VERSION < 2
1329 void GDCMImageIO::Write(const void* buffer)
1330 {
        [...]
1516 if( !header->GetValEntry(0x0020,0x0032 ) )
1517  {
        [write origin in str]
1543  header->InsertValEntry(str.str(),0x0020,0x0032);
1544  }
        [...]
1859 }
1860 #else
1861 void GDCMImageIO::Write(const void* buffer)
1862 {
        [...]
2012 image.SetOrigin(0, m_Origin[0] );
2013 image.SetOrigin(1, m_Origin[1] );
2014 image.SetOrigin(2, m_Origin[2] );
        [...]
2260 }
2261
2262 #endif

----


So if tag (0020|0032) is set in MetaDataDictionary it should be passed
to the image.
But then if MediaStorage is SecondaryCaptureImageStorage (default for
itk) this tag is removed from gdcm::ImageHelper
Otherwise it is replaced with the value of origin set by
gdcm::image::SetOrigin()


---

<from GDCM2 gdcmImageHelper.cxx>
1256   if( ms == MediaStorage::SecondaryCaptureImageStorage )
1257     {
1258     Tag ipp(0x0020,0x0032);
1259     ds.Remove( ipp );
1260     }
         [...]
1316   // Image Position (Patient)
1317   gdcm::Attribute<0x0020,0x0032> ipp = {{0,0,0}}; // default value
1318   ipp.SetValue( origin[0], 0);
1319   ipp.SetValue( origin[1], 1);
1320   ipp.SetValue( origin[2], 2);
1321
1322   ds.Replace( ipp.GetAsDataElement() );

---


So, using GDCM 1 if user sets tag (0020|0032), this tag is in
MetaDataDictionary and in the output DICOM files
Using GDCM 2 this tag is always discarded and due to ImageSeriesWriter
that doesn't set ITK_Origin tag if a MetaDataDictionaryArray is set,
the third value of origin vector is always = 0.
If no MetaDataDictionary Array is set, this value seems to be written
correctly using ITK_Origin.


I hope this time you can follow my description...


Regards,
 Daniele