fix: remove sign flip as it seems incorrect

Author: oesteban

nitransforms/io/itk.py

@@ -348,8 +348,6 @@ def from_image(cls, imgobj):
             hdr.set_intent("vector")
 
         field = np.squeeze(np.asanyarray(imgobj.dataobj)).transpose(2, 1, 0, 3)
-        field[..., (0, 1)] *= -1.0
-
         return imgobj.__class__(field, LPS @ imgobj.affine, hdr)
 
     @classmethod
@@ -360,7 +358,6 @@ def to_image(cls, imgobj):
         hdr.set_intent("vector")
 
         field = imgobj.get_fdata().transpose(2, 1, 0, 3)[..., None, :]
-        field[..., (0, 1)] *= -1.0
         return imgobj.__class__(field, LPS @ imgobj.affine, hdr)
 
 

nitransforms/tests/test_io.py

@@ -9,7 +9,6 @@
 import numpy as np
 import pytest
 
-import SimpleITK as sitk
 import nibabel as nb
 from nibabel.eulerangles import euler2mat
 from nibabel.affines import from_matvec
@@ -19,6 +18,7 @@
     fsl,
     lta as fs,
     itk,
+    x5
 )
 from nitransforms.io.lta import (
     VolumeGeometry as VG,