Fix python3 format issue

Change-Id: If0fed04c8682baee82efbdf5b4f90bcc8e8ac102
diff --git a/tools/3D-Reconstruction/MotionEST/GroundTruth.py b/tools/3D-Reconstruction/MotionEST/GroundTruth.py
index 94bd87a..20eb5f1 100644
--- a/tools/3D-Reconstruction/MotionEST/GroundTruth.py
+++ b/tools/3D-Reconstruction/MotionEST/GroundTruth.py
@@ -22,7 +22,7 @@
     self.name = 'ground truth'
     super(GroundTruth, self).__init__(cur_f, ref_f, blk_sz)
     self.mask = np.zeros((self.num_row, self.num_col), dtype=np.bool)
-    if not gt_path is None:
+    if gt_path:
       with open(gt_path) as gt_file:
         lines = gt_file.readlines()
         for i in xrange(len(lines)):
diff --git a/tools/3D-Reconstruction/MotionEST/MotionEST.py b/tools/3D-Reconstruction/MotionEST/MotionEST.py
index 563fe19..a9a4ace 100644
--- a/tools/3D-Reconstruction/MotionEST/MotionEST.py
+++ b/tools/3D-Reconstruction/MotionEST/MotionEST.py
@@ -67,7 +67,7 @@
     count = 0
     for i in xrange(self.num_row):
       for j in xrange(self.num_col):
-        if not mask is None and mask[i, j]:
+        if mask is not None and mask[i, j]:
           continue
         loss += self.block_dist(i, j, self.mf[i, j], metric)
         count += 1
@@ -82,7 +82,7 @@
     mask = ground_truth.mask
     for i in xrange(self.num_row):
       for j in xrange(self.num_col):
-        if not mask is None and mask[i][j]:
+        if mask is not None and mask[i][j]:
           continue
         loss += LA.norm(gt[i, j] - self.mf[i, j])
         count += 1
@@ -101,7 +101,7 @@
     plt.subplot(1, n_row, 1)
     plt.imshow(cur_mf)
     plt.title('Estimated Motion Field')
-    if not ground_truth is None:
+    if ground_truth is not None:
       plt.subplot(1, n_row, 2)
       plt.imshow(gt_mf)
       plt.title('Ground Truth')
diff --git a/tools/3D-Reconstruction/genY4M/genY4M.py b/tools/3D-Reconstruction/genY4M/genY4M.py
index 4b640e3..6ef5c6c 100644
--- a/tools/3D-Reconstruction/genY4M/genY4M.py
+++ b/tools/3D-Reconstruction/genY4M/genY4M.py
@@ -57,7 +57,7 @@
       else:
         frames.append((idx, img))
   if len(frames) == 0:
-    print "No frames in directory: " + args.frame_path
+    print("No frames in directory: " + args.frame_path)
     sys.exit()
   print("----------------------Y4M Info----------------------")
   print("width:  %d" % frames[0][1].width)