diff --git a/squeeze.py b/squeeze.py
index 59c3563..6df7439 100755
--- a/squeeze.py
+++ b/squeeze.py
@@ -20,8 +20,9 @@ def reduce_precision_tf(x, npp):
     """
     Reduce the precision of image, the tensorflow version.
     """
+    x_clip = tf.clip_by_value(x, 0., 1.)
     npp_int = npp - 1
-    x_int = tf.rint(tf.multiply(x, npp_int))
+    x_int = tf.rint(tf.multiply(x_clip, npp_int))
     x_float = tf.div(x_int, npp_int)
     return x_float
 
diff --git a/utils/visualization.py b/utils/visualization.py
index c612447..1c1de77 100755
--- a/utils/visualization.py
+++ b/utils/visualization.py
@@ -2,23 +2,27 @@
 from PIL import Image
 import numpy as np
 import pdb
+import copy as cp
 from squeeze import median_filter_np, binary_filter_np
 
 IMAGE_SIZE = 28
 
+
 filter_m = lambda x: median_filter_np(x, 3)
 filter_b = lambda x: binary_filter_np(x)
 filter_mb = lambda x: filter_b(filter_m(x))
 filter_bm = lambda x: filter_m(filter_b(x))
 
+
 def show_img(pixel_array, mode=None):
     img = Image.fromarray(pixel_array*255, mode=mode)
     img.show()
 
 
-def show_imgs(imgs, width_num=10, height_num=10, x_margin=2, y_margin=2, fpath='/tmp/test.png'):
-    total_width = width_num * IMAGE_SIZE + (width_num-1)*x_margin
-    total_height = height_num * IMAGE_SIZE + (height_num-1)*y_margin
+adv_x_dict_draw = cp.deepcopy(adv_x_dict)def show_imgs(imgs, width_num=10, height_num=10, x_margin=2, y_margin=2, fpath='/tmp/test.png'):
+    total_width = int(width_num * IMAGE_SIZE + (width_num-1)*x_margin)
+    total_height = int(height_num * IMAGE_SIZE + (height_num-1)*y_margin)
+
 
     new_im = Image.new('RGB', (total_width, total_height), (255,255,255))
 
@@ -53,17 +57,18 @@ def get_first_example_id_each_class(Y_test):
 
 
 def draw_fgsm_adv_examples(adv_x_dict, Y_test, fpath):
+    adv_x_dict_draw = cp.deepcopy(adv_x_dict)
     eps_list = [0,0.1,0.2,0.3,0.4,0.5]
     width_num=10
     selected_example_idx = get_first_example_id_each_class(Y_test)
     imgs = []
 
     for eps in eps_list:
-        adv_x_dict[eps] = adv_x_dict[eps][selected_example_idx,:]
+        adv_x_dict_draw[eps] = adv_x_dict_draw[eps][selected_example_idx,:]
 
     for eps in eps_list:
-        imgs += list(adv_x_dict[eps])
-        imgs += list(filter_b(adv_x_dict[eps]))
+        imgs += list(adv_x_dict_draw[eps])
+        imgs += list(filter_b(adv_x_dict_draw[eps]))
 
     show_imgs(imgs, width_num=width_num, height_num=len(imgs)/width_num, fpath=fpath)