code: # -*- coding: utf-8 -*-
  import matplotlib.pyplot as plt
  
  
  def show_image(image):
      plt.imshow(-image, cmap='Greys')
      plt.show()
  
  
  def show_two(image1, image2):
      plt.subplot(121)
      plt.imshow(-image1, cmap='Greys')
  
      plt.subplot(122)
      plt.imshow(-image2, cmap='Greys')
  
      plt.show()
  
  
  def plot_hist(img):
      plt.hist(img.ravel(), 256, range=(0., 1.), color='red')
      plt.show()
  
  
  def plot_2img_2hist(image1, image2):
  
      plt.subplot(221)
      plt.imshow(-image1, cmap='Greys')
  
      plt.subplot(223)
      plt.hist(image1.ravel(), 256, range=(0., 1.), color='red')
  
      plt.subplot(222)
      plt.imshow(-image2, cmap='Greys')
  
      plt.subplot(224)
      plt.hist(image2.ravel(), 256, range=(0., 1.), color='red')
  
      plt.show()
  
apis: matplotlib.pyplot.imshow matplotlib.pyplot.show matplotlib.pyplot.subplot