title: Normalization images takes long
body: <p>As mentioned below I am normalizing images array with, </p>
  
  <blockquote>
    <p>np.array(training_low_imgs)/127.5 - 1</p>
  </blockquote>
  
  <p>But the problem is it takes too long. So is there a better of doing this? </p>
  
  <pre><code># Training set
  for img_path in train_low_path:
    if img_path.endswith('.png'):
      img = imread(os.path.join(Path().absolute(),"drive/My Drive/LOLdataset/our485/low",img_path))
      img = tf.image.resize(img, [286, 286],
                                  method=tf.image.ResizeMethod.NEAREST_NEIGHBOR)
      training_low_imgs.append(img)
  print('Converting training imgs into numpy array')
  training_low_imgs = np.array(training_low_imgs)/127.5 - 1
  print('Converted training imgs into numpy array')
  </code></pre>