old_contents: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  
  import numpy as np
  import matplotlib.pyplot as plt
  from PIL import Image
  
  import pywt
  import pywt.data
  
  
  arr = pywt.data.aero()
  
  plt.imshow(arr, interpolation="nearest", cmap=plt.cm.gray)
  
  level = 0
  titles = ['Approximation', ' Horizontal detail',
            'Vertical detail', 'Diagonal detail']
  for LL, (LH, HL, HH) in pywt.swt2(arr, 'bior1.3', level=3, start_level=0):
      fig = plt.figure()
      for i, a in enumerate([LL, LH, HL, HH]):
          ax = fig.add_subplot(2, 2, i + 1)
          ax.imshow(a, origin='image', interpolation="nearest", cmap=plt.cm.gray)
          ax.set_title(titles[i], fontsize=12)
  
      fig.suptitle("SWT2 coefficients, level %s" % level, fontsize=14)
      level += 1
  
  
  plt.show()
  
new_contents: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  
  import matplotlib.pyplot as plt
  
  import pywt
  import pywt.data
  
  
  arr = pywt.data.aero()
  
  plt.imshow(arr, interpolation="nearest", cmap=plt.cm.gray)
  
  level = 0
  titles = ['Approximation', ' Horizontal detail',
            'Vertical detail', 'Diagonal detail']
  for LL, (LH, HL, HH) in pywt.swt2(arr, 'bior1.3', level=3, start_level=0):
      fig = plt.figure()
      for i, a in enumerate([LL, LH, HL, HH]):
          ax = fig.add_subplot(2, 2, i + 1)
          ax.imshow(a, origin='image', interpolation="nearest", cmap=plt.cm.gray)
          ax.set_title(titles[i], fontsize=12)
  
      fig.suptitle("SWT2 coefficients, level %s" % level, fontsize=14)
      level += 1
  
  
  plt.show()
  
subject: remove unused imports from demo