fix the shape assertion in impad (#172)

mmcv/image/transforms/geometry.py

@@ -180,7 +180,7 @@ def impad(img, shape, pad_val=0):
     if len(shape) < len(img.shape):
         shape = shape + (img.shape[-1], )
     assert len(shape) == len(img.shape)
-    for i in range(len(shape) - 1):
+    for i in range(len(shape)):
         assert shape[i] >= img.shape[i]
     pad = np.empty(shape, dtype=img.dtype)
     pad[...] = pad_val

mmcv/version.py

 # Copyright (c) Open-MMLab. All rights reserved.
-__version__ = '0.2.15'
+__version__ = '0.2.16'

tests/test_image.py

@@ -281,6 +281,16 @@ class TestImage(object):
             self.assert_img_equal(patches[i], ref_patch)
 
     def test_impad(self):
+        # grayscale image
+        img = np.random.rand(10, 10).astype(np.float32)
+        padded_img = mmcv.impad(img, (15, 12), 0)
+        assert_array_equal(img, padded_img[:10, :10])
+        assert_array_equal(
+            np.zeros((5, 12), dtype='float32'), padded_img[10:, :])
+        assert_array_equal(
+            np.zeros((15, 2), dtype='float32'), padded_img[:, 10:])
+
+        # RGB image
         img = np.random.rand(10, 10, 3).astype(np.float32)
         padded_img = mmcv.impad(img, (15, 12), 0)
         assert_array_equal(img, padded_img[:10, :10, :])