import matplotlib.pyplot as plt

def plot_image(image):
    """
    Plots an image.
    """
    plt.figure(figsize=(12, 4))
    plt.imshow(image, cmap='gray')
    plt.axis('off')
    plt.show()

def plot_result(*args):
  number_images = len(args)
  fig, axis = plt.subplots(nrows=1, ncols=number_images, figsize=(12, 4))
  names_lst = ['Image{}'.format(i) for i in range(1, number_images)]
  names_lst.append('Result')
  for ax, name, image in zip(axis, names_lst, args):
    ax.set_title(name)
    ax.imshow(image, cmap='gray')
    ax.axis('off')
  fig.tight_layout()
  plt.show()

def plot_histogram(image):
  fig, axis = plt.subplots(nrows=1, ncols=3, figsize=(12, 4), sharex=True, sharey=True)
  color_lst = ['red', 'green', 'blue']
  for index, (ax, color) in enumerate(zip(axis, color_lst)):
    ax.set_title('Histogram {}'.format(color.title()))
    ax.hist(image[:, :, index].ravel(), bins=256, color=color, alpha=0.8)
  fig.tight_layout()
  plt.show()