class_docstr: 2D images, axcodes specifications are ignored when
  loading. (Resampling to new pixdims is currently not supported).
class_docstr_tok: ["2D","images",",","axcodes","specifications","are","ignored","when","loading",".","(","Resampling","to","new","pixdims","is","currently","not","supported",")","."]
docstr: read original header for pixdim and affine info
  
  :return:
docstr_tok: ["read","original","header","for","pixdim","and","affine","info",":","return",":"]
code: def _load_header(self):
      """
      read original header for pixdim and affine info
  
      :return:
      """
      self._original_pixdim = []
      self._original_affine = []
      for file_i, loader_i in zip(self.file_path, self.loader):
          image_obj = load_image_obj(file_i, loader_i)
          try:
              misc.correct_image_if_necessary(image_obj)
              self._original_pixdim.append(
                  image_obj.header.get_zooms()[:3]
              )
              self._original_affine.append(image_obj.affine)
          except (TypeError, IndexError, AttributeError):
              tf.logging.fatal("could not read header from %s", file_i)
              raise ValueError
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import os
  from abc import ABCMeta, abstractmethod
  import nibabel
  import numpy
  import tensorflow
  from six import with_metaclass, string_types
  import niftynet.io.misc_io
  from niftynet.io.image_loader import load_image_obj
  from niftynet.io.misc_io import resolve_file_name, dtype_casting
  from niftynet.utilities.niftynet_global_config import NiftyNetGlobalConfig
label_desc: Use image node_id 5 for calling the SpatialImage2D obj's underlying member method code with example usage: obj._load_header() without return types