[Feature] Add RandomRotate transform (open-mmlab#215)

* add RandomRotate for transforms

* change rotation function to mmcv.imrotate

* refactor

* add unittest

* fixed test

* fixed docstring

* fixed test

* add more test

* fixed repr

* rename to prob

* fixed unittest

Co-authored-by: hkzhang95 <[email protected]>

Author: xvjiarui

configs/_base_/datasets/ade20k.py

@@ -9,7 +9,7 @@
     dict(type='LoadAnnotations', reduce_zero_label=True),
     dict(type='Resize', img_scale=(2048, 512), ratio_range=(0.5, 2.0)),
     dict(type='RandomCrop', crop_size=crop_size, cat_max_ratio=0.75),
-    dict(type='RandomFlip', flip_ratio=0.5),
+    dict(type='RandomFlip', prob=0.5),
     dict(type='PhotoMetricDistortion'),
     dict(type='Normalize', **img_norm_cfg),
     dict(type='Pad', size=crop_size, pad_val=0, seg_pad_val=255),

configs/_base_/datasets/cityscapes.py

@@ -9,7 +9,7 @@
     dict(type='LoadAnnotations'),
     dict(type='Resize', img_scale=(2048, 1024), ratio_range=(0.5, 2.0)),
     dict(type='RandomCrop', crop_size=crop_size, cat_max_ratio=0.75),
-    dict(type='RandomFlip', flip_ratio=0.5),
+    dict(type='RandomFlip', prob=0.5),
     dict(type='PhotoMetricDistortion'),
     dict(type='Normalize', **img_norm_cfg),
     dict(type='Pad', size=crop_size, pad_val=0, seg_pad_val=255),

configs/_base_/datasets/cityscapes_769x769.py

@@ -7,7 +7,7 @@
     dict(type='LoadAnnotations'),
     dict(type='Resize', img_scale=(2049, 1025), ratio_range=(0.5, 2.0)),
     dict(type='RandomCrop', crop_size=crop_size, cat_max_ratio=0.75),
-    dict(type='RandomFlip', flip_ratio=0.5),
+    dict(type='RandomFlip', prob=0.5),
     dict(type='PhotoMetricDistortion'),
     dict(type='Normalize', **img_norm_cfg),
     dict(type='Pad', size=crop_size, pad_val=0, seg_pad_val=255),

configs/_base_/datasets/pascal_context.py

@@ -12,7 +12,7 @@
     dict(type='LoadAnnotations'),
     dict(type='Resize', img_scale=img_scale, ratio_range=(0.5, 2.0)),
     dict(type='RandomCrop', crop_size=crop_size, cat_max_ratio=0.75),
-    dict(type='RandomFlip', flip_ratio=0.5),
+    dict(type='RandomFlip', prob=0.5),
     dict(type='PhotoMetricDistortion'),
     dict(type='Normalize', **img_norm_cfg),
     dict(type='Pad', size=crop_size, pad_val=0, seg_pad_val=255),

configs/_base_/datasets/pascal_voc12.py

@@ -9,7 +9,7 @@
     dict(type='LoadAnnotations'),
     dict(type='Resize', img_scale=(2048, 512), ratio_range=(0.5, 2.0)),
     dict(type='RandomCrop', crop_size=crop_size, cat_max_ratio=0.75),
-    dict(type='RandomFlip', flip_ratio=0.5),
+    dict(type='RandomFlip', prob=0.5),
     dict(type='PhotoMetricDistortion'),
     dict(type='Normalize', **img_norm_cfg),
     dict(type='Pad', size=crop_size, pad_val=0, seg_pad_val=255),

mmseg/datasets/pipelines/transforms.py

@@ -1,5 +1,6 @@
 import mmcv
 import numpy as np
+from mmcv.utils import deprecated_api_warning
 from numpy import random
 
 from ..builder import PIPELINES
@@ -232,16 +233,17 @@ class RandomFlip(object):
     method.
 
     Args:
-        flip_ratio (float, optional): The flipping probability. Default: None.
+        prob (float, optional): The flipping probability. Default: None.
         direction(str, optional): The flipping direction. Options are
             'horizontal' and 'vertical'. Default: 'horizontal'.
     """
 
-    def __init__(self, flip_ratio=None, direction='horizontal'):
-        self.flip_ratio = flip_ratio
+    @deprecated_api_warning({'flip_ratio': 'prob'}, cls_name='RandomFlip')
+    def __init__(self, prob=None, direction='horizontal'):
+        self.prob = prob
         self.direction = direction
-        if flip_ratio is not None:
-            assert flip_ratio >= 0 and flip_ratio <= 1
+        if prob is not None:
+            assert prob >= 0 and prob <= 1
         assert direction in ['horizontal', 'vertical']
 
     def __call__(self, results):
@@ -257,7 +259,7 @@ def __call__(self, results):
         """
 
         if 'flip' not in results:
-            flip = True if np.random.rand() < self.flip_ratio else False
+            flip = True if np.random.rand() < self.prob else False
             results['flip'] = flip
         if 'flip_direction' not in results:
             results['flip_direction'] = self.direction
@@ -274,7 +276,7 @@ def __call__(self, results):
         return results
 
     def __repr__(self):
-        return self.__class__.__name__ + f'(flip_ratio={self.flip_ratio})'
+        return self.__class__.__name__ + f'(prob={self.prob})'
 
 
 @PIPELINES.register_module()
@@ -463,6 +465,89 @@ def __repr__(self):
         return self.__class__.__name__ + f'(crop_size={self.crop_size})'
 
 
+@PIPELINES.register_module()
+class RandomRotate(object):
+    """Rotate the image & seg.
+
+    Args:
+        prob (float): The rotation probability.
+        degree (float, tuple[float]): Range of degrees to select from. If
+            degree is a number instead of tuple like (min, max),
+            the range of degree will be (``-degree``, ``+degree``)
+        pad_val (float, optional): Padding value of image. Default: 0.
+        seg_pad_val (float, optional): Padding value of segmentation map.
+            Default: 255.
+        center (tuple[float], optional): Center point (w, h) of the rotation in
+            the source image. If not specified, the center of the image will be
+            used. Default: None.
+        auto_bound (bool): Whether to adjust the image size to cover the whole
+            rotated image. Default: False
+    """
+
+    def __init__(self,
+                 prob,
+                 degree,
+                 pad_val=0,
+                 seg_pad_val=255,
+                 center=None,
+                 auto_bound=False):
+        self.prob = prob
+        assert prob >= 0 and prob <= 1
+        if isinstance(degree, (float, int)):
+            assert degree > 0, f'degree {degree} should be positive'
+            self.degree = (-degree, degree)
+        else:
+            self.degree = degree
+        assert len(self.degree) == 2, f'degree {self.degree} should be a ' \
+                                      f'tuple of (min, max)'
+        self.pal_val = pad_val
+        self.seg_pad_val = seg_pad_val
+        self.center = center
+        self.auto_bound = auto_bound
+
+    def __call__(self, results):
+        """Call function to rotate image, semantic segmentation maps.
+
+        Args:
+            results (dict): Result dict from loading pipeline.
+
+        Returns:
+            dict: Rotated results.
+        """
+
+        rotate = True if np.random.rand() < self.prob else False
+        degree = np.random.uniform(min(*self.degree), max(*self.degree))
+        if rotate:
+            # rotate image
+            results['img'] = mmcv.imrotate(
+                results['img'],
+                angle=degree,
+                border_value=self.pal_val,
+                center=self.center,
+                auto_bound=self.auto_bound)
+
+            # rotate segs
+            for key in results.get('seg_fields', []):
+                results[key] = mmcv.imrotate(
+                    results[key],
+                    angle=degree,
+                    border_value=self.seg_pad_val,
+                    center=self.center,
+                    auto_bound=self.auto_bound,
+                    interpolation='nearest')
+        return results
+
+    def __repr__(self):
+        repr_str = self.__class__.__name__
+        repr_str += f'(prob={self.prob}, ' \
+                    f'degree={self.degree}, ' \
+                    f'pad_val={self.pal_val}, ' \
+                    f'seg_pad_val={self.seg_pad_val}, ' \
+                    f'center={self.center}, ' \
+                    f'auto_bound={self.auto_bound})'
+        return repr_str
+
+
 @PIPELINES.register_module()
 class SegRescale(object):
     """Rescale semantic segmentation maps.

tests/test_data/test_dataset.py

@@ -69,7 +69,7 @@ def test_custom_dataset():
         dict(type='LoadAnnotations'),
         dict(type='Resize', img_scale=(128, 256), ratio_range=(0.5, 2.0)),
         dict(type='RandomCrop', crop_size=crop_size, cat_max_ratio=0.75),
-        dict(type='RandomFlip', flip_ratio=0.5),
+        dict(type='RandomFlip', prob=0.5),
         dict(type='PhotoMetricDistortion'),
         dict(type='Normalize', **img_norm_cfg),
         dict(type='Pad', size=crop_size, pad_val=0, seg_pad_val=255),

tests/test_data/test_transform.py

@@ -94,18 +94,17 @@ def test_resize():
 
 
 def test_flip():
-    # test assertion for invalid flip_ratio
+    # test assertion for invalid prob
     with pytest.raises(AssertionError):
-        transform = dict(type='RandomFlip', flip_ratio=1.5)
+        transform = dict(type='RandomFlip', prob=1.5)
         build_from_cfg(transform, PIPELINES)
 
     # test assertion for invalid direction
     with pytest.raises(AssertionError):
-        transform = dict(
-            type='RandomFlip', flip_ratio=1, direction='horizonta')
+        transform = dict(type='RandomFlip', prob=1, direction='horizonta')
         build_from_cfg(transform, PIPELINES)
 
-    transform = dict(type='RandomFlip', flip_ratio=1)
+    transform = dict(type='RandomFlip', prob=1)
     flip_module = build_from_cfg(transform, PIPELINES)
 
     results = dict()
@@ -197,6 +196,47 @@ def test_pad():
     assert img_shape[1] % 32 == 0
 
 
+def test_rotate():
+    # test assertion degree should be tuple[float] or float
+    with pytest.raises(AssertionError):
+        transform = dict(type='RandomRotate', prob=0.5, degree=-10)
+        build_from_cfg(transform, PIPELINES)
+    # test assertion degree should be tuple[float] or float
+    with pytest.raises(AssertionError):
+        transform = dict(type='RandomRotate', prob=0.5, degree=(10., 20., 30.))
+        build_from_cfg(transform, PIPELINES)
+
+    transform = dict(type='RandomRotate', degree=10., prob=1.)
+    transform = build_from_cfg(transform, PIPELINES)
+
+    assert str(transform) == f'RandomRotate(' \
+                             f'prob={1.}, ' \
+                             f'degree=({-10.}, {10.}), ' \
+                             f'pad_val={0}, ' \
+                             f'seg_pad_val={255}, ' \
+                             f'center={None}, ' \
+                             f'auto_bound={False})'
+
+    results = dict()
+    img = mmcv.imread(
+        osp.join(osp.dirname(__file__), '../data/color.jpg'), 'color')
+    h, w, _ = img.shape
+    seg = np.array(
+        Image.open(osp.join(osp.dirname(__file__), '../data/seg.png')))
+    results['img'] = img
+    results['gt_semantic_seg'] = seg
+    results['seg_fields'] = ['gt_semantic_seg']
+    results['img_shape'] = img.shape
+    results['ori_shape'] = img.shape
+    # Set initial values for default meta_keys
+    results['pad_shape'] = img.shape
+    results['scale_factor'] = 1.0
+
+    results = transform(results)
+    assert results['img'].shape[:2] == (h, w)
+    assert results['gt_semantic_seg'].shape[:2] == (h, w)
+
+
 def test_normalize():
     img_norm_cfg = dict(
         mean=[123.675, 116.28, 103.53],