title: convert mss screenshot to pil image
body: <p>Im using mss to take a screenshot because it apparently can take fast screenshots. So is there a way to convert it into an image without saving it on my computer(its faster) like image.grab() in pillow. This is because i need to perform various actions like cropping finding the colour for which pillow is useful.</p>
  
  <pre><code>Traceback (most recent call last):
    File "/Users/Hari/Desktop/stuff/Tetris/test.py", line 84, in &lt;module&gt;
      img = im.crop((40*i+376, 40*j+485, 40*i+396, 40*j+505))
  AttributeError: 'ScreenShot' object has no attribute 'crop'
  
  
  with mss.mss() as sct:
      monitor = sct.monitors[1]
      im = sct.grab(monitor)
  
  for i in range(0,10):
      for j in range(0, 18):
          img = im.crop((40*i+376, 40*j+485, 40*i+396, 40*j+505))
          rgb = img.convert('RGB')
          r, g, b = rgb.getpixel((1, 1))
  </code></pre>