Resizing Transform

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 | Date | Commit | Short Description | Breaking Changes? |
 | ---- | --------- | ----------------- | ----------------- |
+| 2020-02-17 | 26d7c9432b90247f8b9e0ab3e6881e88fb7749d4 | Add Resizing Transform | No |
 | 2020-01-03 | 6b9a7b2fdc7d0b894c0dfcfd94237845fe8b8672 | Affine Trafos | No|
 | 2019-12-24 | 6b90197e89dedd7659073bf72037390231a1c278 | Use shared memory for progressive resizing | No |
 | 2019-12-17 | 0b881f8e0ce85f380ecf458080c2a3f5cb8c3080 | User-Controllable call dispatch within the compose class | No |

rising/transforms/affine.py

@@ -2,15 +2,17 @@
 from rising.transforms.functional.affine import affine_image_transform
 from rising.utils.affine import AffineParamType, \
     assemble_matrix_if_necessary, matrix_to_homogeneous, matrix_to_cartesian
+from rising.utils.checktype import check_scalar
 import torch
-from typing import Sequence, Union
+from typing import Sequence, Union, Iterable
 
 __all__ = [
     'Affine',
     'StackedAffine',
     'Rotate',
     'Scale',
-    'Translate'
+    'Translate',
+    'Resize',
 ]
 
 
@@ -583,5 +585,97 @@ def assemble_matrix(self, **data) -> torch.Tensor:
 
         return matrix_to_cartesian(whole_trafo)
 
-# TODO: Add transforms around image center
-# TODO: Add Resize Transform
+
+class Resize(Scale):
+    def __init__(self,
+                 size: Union[int, Iterable],
+                 keys: Sequence = ('data',),
+                 grad: bool = False,
+                 interpolation_mode: str = 'bilinear',
+                 padding_mode: str = 'zeros',
+                 align_corners: bool = False,
+                 **kwargs):
+        """
+        Class Performing a Resizing Affine Transformation on a given
+        sample dict.
+        The transformation will be applied to all the dict-entries specified
+        in :attr:`keys`.
+
+        Parameters
+        ----------
+        size : int, Iterable
+            the target size. If int, this will be repeated for all the
+            dimensions
+        keys: Sequence
+            keys which should be augmented
+        grad: bool
+            enable gradient computation inside transformation
+        interpolation_mode : str
+            interpolation mode to calculate output values
+            'bilinear' | 'nearest'. Default: 'bilinear'
+        padding_mode :
+            padding mode for outside grid values
+            'zeros' | 'border' | 'reflection'. Default: 'zeros'
+        align_corners : Geometrically, we consider the pixels of the input as
+            squares rather than points. If set to True, the extrema (-1 and 1)
+            are considered as referring to the center points of the input’s
+            corner pixels. If set to False, they are instead considered as
+            referring to the corner points of the input’s corner pixels,
+            making the sampling more resolution agnostic.
+        **kwargs :
+            additional keyword arguments passed to the affine transform
+
+        Note
+        ----
+        The offsets for shifting back and to origin are calculated on the
+        entry matching the first item iin :attr:`keys` for each batch
+
+        Note
+        ----
+        The target size must be specified in x, y (,z) order and will be
+        converted to (D,) H, W order internally
+
+        """
+        super().__init__(output_size=size,
+                         scale=None,
+                         keys=keys,
+                         grad=grad,
+                         adjust_size=False,
+                         interpolation_mode=interpolation_mode,
+                         padding_mode=padding_mode,
+                         align_corners=align_corners,
+                         **kwargs)
+
+    def assemble_matrix(self, **data) -> torch.Tensor:
+        """
+        Handles the matrix assembly and calculates the scale factors for
+        resizing
+
+        Parameters
+        ----------
+        **data :
+            the data to be transformed. Will be used to determine batchsize,
+            dimensionality, dtype and device
+
+        Returns
+        -------
+        torch.Tensor
+            the (batched) transformation matrix
+
+        """
+        curr_img_size = data[self.keys[0]].shape[2:]
+
+        was_scalar = check_scalar(self.output_size)
+
+        if was_scalar:
+            self.output_size = [self.output_size] * len(curr_img_size)
+
+        self.scale = [self.output_size[i] / curr_img_size[-i]
+                      for i in range(len(curr_img_size))]
+
+        matrix = super().assemble_matrix(**data)
+
+        if was_scalar:
+            self.output_size = self.output_size[0]
+
+        return matrix

tests/transforms/test_affine.py

@@ -1,6 +1,6 @@
 import unittest
 from rising.transforms.affine import Affine, StackedAffine, Translate, Rotate, \
-    Scale
+    Scale, Resize
 import torch
 from copy import deepcopy
 from rising.utils.affine import matrix_to_cartesian, matrix_to_homogeneous
@@ -83,13 +83,16 @@ def test_affine_subtypes(self):
         trafos = [
             Scale(5),
             Rotate(45),
-            Translate(10)
+            Translate(10),
+            Resize((5, 4))
         ]
 
         for trafo in trafos:
             with self.subTest(trafo=trafo):
                 self.assertIsInstance(trafo(**sample)['data'], torch.Tensor)
 
+        self.assertTupleEqual((5, 4), trafos[-1](**sample)['data'].shape[2:])
+
 
 if __name__ == '__main__':
     unittest.main()