[Insight-users] Question regarding itkNiftiIO

[Erik Tuerke]

Hi

In the itkNiftiImageIO.cxx i discovered something what is kind of inconclusively to me.

line 1533, itk version 3.16

m_Origin[0] = -theMat.m[0][3];
if(dims > 1)
 {
 m_Origin[1] = -theMat.m[1][3];
 }
if(dims > 2)
 {
 m_Origin[2] = theMat.m[2][3];
 }

When writing a nifti file from an external source (not red by the itkImageFileReader), i noticed different orientation in both the input image (which was red by a not-itk-reader) and the output image (what was written by an itk-writer).
When reading the image with the itkReader this difference does not occur. So i think those negation is done by the reader as well (unfortunately did not find the code for this, yet).
What is the sense of this? Why is itk internally using different orientation then stored in the file?

Thanks in advance

cheers

-- 
Erik Türke
Department of Neurophysics 
Max-Planck-Institute for Human Cognitive and Brain Sciences
Stephanstrasse 1A
04103 Leipzig
Germany 
Tel: +49 341 99 40-2440
Email: tuerke at cbs.mpg.de
www.cbs.mpg.de