Merge pull request #855 from ANTsX/itk_nifti_transforms

ENH: Read ITK metadata from image on disk
ENH: Allow user more control over nifti xform

Author: cookpa

ants/core/__init__.py

@@ -6,7 +6,8 @@
                             make_image,
                             from_numpy,
                             from_numpy_like,
-                            new_image_like)
+                            new_image_like,
+                            read_image_metadata)
 from .ants_image import (ANTsImage,
                          copy_image_info,
                          set_origin,

ants/core/ants_image_io.py

@@ -11,7 +11,8 @@
     "make_image",
     "from_numpy",
     "from_numpy_like",
-    "new_image_like"
+    "new_image_like",
+    "read_image_metadata",
 ]
 
 import os
@@ -531,4 +532,25 @@ def new_image_like(image, data):
         has_components=image.has_components)
 
 def from_numpy_like(data, image):
-    return new_image_like(image, data)
+    return new_image_like(image, data)
+
+def read_image_metadata(filename):
+    """
+    Read metadata dictionary from image file. This uses ITK ImageIO to efficiently read the metadata without reading the pixel
+    data.
+
+    Arguments
+    ---------
+    filename : string
+        name of image file from which metadata will be read.
+
+    Returns
+    -------
+    dict
+    """
+    if not os.path.exists(filename):
+        raise Exception("filename does not exist")
+
+    libfn = get_lib_fn("readImageMetadata")
+    retval = libfn(filename)
+    return retval

ants/utils/__init__.py

@@ -15,3 +15,5 @@
 from .sitk_to_ants import from_sitk, to_sitk
 from .convergence_monitoring import convergence_monitoring
 from .polar_decomposition import polar_decomposition
+from .nifti_utils import (deshear_nifti_sform, get_nifti_sform_shear, get_nifti_qform_spatial_info, get_nifti_sform_spatial_info,
+                          get_nifti_spatial_transform_from_metadata, set_nifti_spatial_transform_from_metadata)