fix potential numericall error bug (#337)

* add _augment_coords implementation for many ImageAugmentor subclasses

* Fxied style issue

* Fixed style issues

* Added AugmentImageCoordinates

* Fixed stype issues

* remove unused comments

* fix potential numericall error bug

tensorpack/dataflow/imgaug/noname.py

@@ -85,8 +85,8 @@ class Resize(ImageAugmentor):
 
     def _augment_coords(self, coords, param):
         h, w = param
-        coords[:, 0] = coords[:, 0] * self.shape[1] * 1.0 / w
-        coords[:, 1] = coords[:, 1] * self.shape[0] * 1.0 / h
+        coords[:, 0] = coords[:, 0] * (self.shape[1] * 1.0 / w)
+        coords[:, 1] = coords[:, 1] * (self.shape[0] * 1.0 / h)
         return coords
 
 
@@ -119,8 +119,8 @@ class ResizeShortestEdge(ImageAugmentor):
 
     def _augment_coords(self, coords, param):
         h, w, newh, neww = param
-        coords[:, 0] = coords[:, 0] * neww * 1.0 / w
-        coords[:, 1] = coords[:, 1] * newh * 1.0 / h
+        coords[:, 0] = coords[:, 0] * (neww * 1.0 / w)
+        coords[:, 1] = coords[:, 1] * (newh * 1.0 / h)
         return coords
 
 
@@ -174,8 +174,8 @@ class RandomResize(ImageAugmentor):
 
     def _augment_coords(self, coords, param):
         h, w, newh, neww = param
-        coords[:, 0] = coords[:, 0] * neww * 1.0 / w
-        coords[:, 1] = coords[:, 1] * newh * 1.0 / h
+        coords[:, 0] = coords[:, 0] * (neww * 1.0 / w)
+        coords[:, 1] = coords[:, 1] * (newh * 1.0 / h)
         return coords