[STN] integer clip_by_value is so slow..

tensorpack/models/image_sample.py

@@ -20,14 +20,14 @@ def sample(img, coords):
     Return:
         bxh2xw2xc image
     """
-    coords = tf.to_int32(coords)
     shape = img.get_shape().as_list()[1:]   # h, w, c
     batch = tf.shape(img)[0]
     shape2 = coords.get_shape().as_list()[1:3]  # h2, w2
     assert None not in shape2, coords.get_shape()
-    max_coor = tf.constant([shape[0] - 1, shape[1] - 1], dtype=tf.int32)
+    max_coor = tf.constant([shape[0] - 1, shape[1] - 1], dtype=tf.float32)
 
-    coords = tf.clip_by_value(coords, 0, max_coor)  # borderMode==repeat
+    coords = tf.clip_by_value(coords, 0., max_coor)  # borderMode==repeat
+    coords = tf.to_int32(coords)
 
     batch_index = tf.range(batch, dtype=tf.int32)
     batch_index = tf.reshape(batch_index, [-1, 1, 1, 1])