Fix flip_keypoint to accept keypoints on the edge

chainercv/transforms/keypoint/flip_keypoint.py

@@ -22,7 +22,7 @@ def flip_keypoint(keypoint, size, y_flip=False, x_flip=False):
     H, W = size
     keypoint = keypoint.copy()
     if y_flip:
-        keypoint[:, 0] = H - 1 - keypoint[:, 0]
+        keypoint[:, 0] = H - keypoint[:, 0]
     if x_flip:
-        keypoint[:, 1] = W - 1 - keypoint[:, 1]
+        keypoint[:, 1] = W - keypoint[:, 1]
     return keypoint

tests/transforms_tests/keypoint_tests/test_flip_keypoint.py

@@ -14,12 +14,12 @@ def test_flip_keypoint(self):
 
         out = flip_keypoint(keypoint, size=(34, 32), y_flip=True)
         keypoint_expected = keypoint.copy()
-        keypoint_expected[:, 0] = 33 - keypoint[:, 0]
+        keypoint_expected[:, 0] = 34 - keypoint[:, 0]
         np.testing.assert_equal(out, keypoint_expected)
 
         out = flip_keypoint(keypoint, size=(34, 32), x_flip=True)
         keypoint_expected = keypoint.copy()
-        keypoint_expected[:, 1] = 31 - keypoint[:, 1]
+        keypoint_expected[:, 1] = 32 - keypoint[:, 1]
         np.testing.assert_equal(out, keypoint_expected)