diff --git a/python/paddle/dataset/image.py b/python/paddle/dataset/image.py
index f7e7c854fe4059b20b6ded8a945497527877bcc1..99d2c5f8993215647ae9539df7857aa0d847d328 100644
--- a/python/paddle/dataset/image.py
+++ b/python/paddle/dataset/image.py
@@ -33,6 +33,11 @@ import numpy as np
 try:
     import cv2
 except ImportError:
+    import sys
+    sys.stderr.write(
+        '''Warning with paddle image module: opencv-python should be imported,
+    or paddle image module could NOT work; please install opencv-python first.'''
+    )
     cv2 = None
 import os
 import tarfile
@@ -126,6 +131,8 @@ def load_image_bytes(bytes, is_color=True):
                      load and return a gray image.
     :type is_color: bool
     """
+    assert cv2 is not None
+
     flag = 1 if is_color else 0
     file_bytes = np.asarray(bytearray(bytes), dtype=np.uint8)
     img = cv2.imdecode(file_bytes, flag)
@@ -149,6 +156,8 @@ def load_image(file, is_color=True):
                      load and return a gray image.
     :type is_color: bool
     """
+    assert cv2 is not None
+
     # cv2.IMAGE_COLOR for OpenCV3
     # cv2.CV_LOAD_IMAGE_COLOR for older OpenCV Version
     # cv2.IMAGE_GRAYSCALE for OpenCV3
@@ -176,12 +185,14 @@ def resize_short(im, size):
     :param size: the shorter edge size of image after resizing.
     :type size: int
     """
+    assert cv2 is not None
+
     h, w = im.shape[:2]
     h_new, w_new = size, size
     if h > w:
-        h_new = size * h / w
+        h_new = size * h // w
     else:
-        w_new = size * w / h
+        w_new = size * w // h
     im = cv2.resize(im, (h_new, w_new), interpolation=cv2.INTER_CUBIC)
     return im
 
@@ -228,8 +239,8 @@ def center_crop(im, size, is_color=True):
     :type is_color: bool
     """
     h, w = im.shape[:2]
-    h_start = (h - size) / 2
-    w_start = (w - size) / 2
+    h_start = (h - size) // 2
+    w_start = (w - size) // 2
     h_end, w_end = h_start + size, w_start + size
     if is_color:
         im = im[h_start:h_end, w_start:w_end, :]
diff --git a/python/paddle/fluid/tests/unittests/op_test.py b/python/paddle/fluid/tests/unittests/op_test.py
index 1ed14e35b1b6e9a2e2304c87aff20fda8faff9ec..ada4ad70f0c07dfc25df2ecde82f9c83e5987db8 100644
--- a/python/paddle/fluid/tests/unittests/op_test.py
+++ b/python/paddle/fluid/tests/unittests/op_test.py
@@ -362,9 +362,14 @@ class OpTest(unittest.TestCase):
 
     def check_output_customized(self, checker):
         places = self._get_places()
+        import sys
+        print('places', places)
         for place in places:
             outs = self.calc_output(place)
             outs = [np.array(out) for out in outs]
+            import sys
+            print('outs', outs)
+            sys.stdout.flush()
             checker(outs)
 
     def __assert_is_close(self, numeric_grads, analytic_grads, names,
diff --git a/python/paddle/reader/decorator.py b/python/paddle/reader/decorator.py
index ce410e61b92e7d3f32fa5bfeb415e4b6c5fa9df6..d53694959b63891addb694e92fc8c27e475dbc19 100644
--- a/python/paddle/reader/decorator.py
+++ b/python/paddle/reader/decorator.py
@@ -27,6 +27,7 @@ from six.moves import zip
 import itertools
 import random
 import zlib
+import paddle.fluid.compat as cpt
 
 
 def map_readers(func, *readers):
@@ -390,9 +391,9 @@ class PipeReader:
             buff = self.process.stdout.read(self.bufsize)
             if buff:
                 if self.file_type == "gzip":
-                    decomp_buff = self.dec.decompress(buff)
+                    decomp_buff = cpt.to_literal_str(self.dec.decompress(buff))
                 elif self.file_type == "plain":
-                    decomp_buff = buff
+                    decomp_buff = cpt.to_literal_str(buff)
                 else:
                     raise TypeError("file_type %s is not allowed" %
                                     self.file_type)