--- a
+++ b/ants/ops/pad_image.py
@@ -0,0 +1,82 @@
+
+__all__ = ['pad_image']
+
+import math
+
+import ants
+from ants.decorators import image_method
+from ants.internal import get_lib_fn
+
+@image_method
+def pad_image(image, shape=None, pad_width=None, value=0.0, return_padvals=False):
+    """
+    Pad an image to have the given shape or to be isotropic.
+
+    Arguments
+    ---------
+    image : ANTsImage
+        image to pad
+
+    shape : tuple
+        - if shape is given, the image will be padded in each dimension
+          until it has this shape
+        - if shape and pad_width are both None, the image will be padded along
+          each dimension to match the largest existing dimension so that it has
+          isotropic dimensions.
+
+    pad_width : list of integers or list-of-list of integers
+        How much to pad in each direction. If a single list is
+        supplied (e.g., [4,4,4]), then the image will be padded by half
+        that amount on both sides. If a list-of-list is supplied
+        (e.g., [(0,4),(0,4),(0,4)]), then the image will be
+        padded unevenly on the different sides
+
+    pad_value : scalar
+        value with which image will be padded
+
+    Example
+    -------
+    >>> import ants
+    >>> img = ants.image_read(ants.get_data('r16'))
+    >>> img2 = ants.pad_image(img, shape=(300,300))
+    >>> mni = ants.image_read(ants.get_data('mni'))
+    >>> mni2 = ants.pad_image(mni)
+    >>> mni3 = ants.pad_image(mni, pad_width=[(0,4),(0,4),(0,4)])
+    >>> mni4 = ants.pad_image(mni, pad_width=(4,4,4))
+    """
+    inpixeltype = image.pixeltype
+    ndim = image.dimension
+    if image.pixeltype != 'float':
+        image = image.clone('float')
+
+    if pad_width is None:
+        if shape is None:
+            shape = [max(image.shape)] * image.dimension
+        lower_pad_vals = [math.floor(max(ns-os,0)/2) for os,ns in zip(image.shape, shape)]
+        upper_pad_vals = [math.ceil(max(ns-os,0)/2) for os,ns in zip(image.shape, shape)]
+    else:
+        if shape is not None:
+            raise ValueError('Cannot give both `shape` and `pad_width`. Pick one!')
+        if len(pad_width) != image.dimension:
+            raise ValueError('Must give pad width for each image dimension')
+
+        lower_pad_vals = []
+        upper_pad_vals = []
+        for p in pad_width:
+            if isinstance(p, (list, tuple)):
+                lower_pad_vals.append(p[0])
+                upper_pad_vals.append(p[1])
+            else:
+                lower_pad_vals.append(math.floor(p/2))
+                upper_pad_vals.append(math.ceil(p/2))
+
+    libfn = get_lib_fn('padImage')
+    itkimage = libfn(image.pointer, lower_pad_vals, upper_pad_vals, value)
+
+    new_image = ants.from_pointer(itkimage).clone(inpixeltype)
+    if return_padvals:
+        return new_image, lower_pad_vals, upper_pad_vals
+    else:
+        return new_image
+
+