title: Python PIL: image crop with black area if not enough photo region
body: <p>I want to make thumb and crop it to needed size. It works fine, but if my new thumb area is smaller than crop one, all empty space fills with black color.
  Code:</p>
  
  <pre><code>import os
  from PIL import Image
  
  def resize(file_path):
      file, ext = os.path.splitext(file_path)
      im = Image.open(file_path)
      size = (100, 'auto')
      new_path = file + "_.jpg"
      im.thumbnail(size, Image.ANTIALIAS)
      region = im.crop((0, 0, 100, 100))
      region.save(new_path, "JPEG")
  </code></pre>
  
  <p>Maybe there is some option like max_height for crop method or anything else?</p>
  
  <p>Thanks!
  <img src="https://i.stack.imgur.com/XI3zX.jpg" alt="enter image description here"></p>