title: How to convert PIL Image.image object to base64 string?
body: <p>I am trying to manipulate a base64 encoded image in such a way as to rotate it at 90 angle. After this manipulation, I want to convert it back to base64 string. But unfortunately unable to achieve this yet. </p>
  
  <p>Here is what I have done so far:</p>
  
  <pre><code>image_string = StringIO(base64.b64decode(base64_string_here))
  image = Image.open(image_string)
  angle = 90
  rotated_image = image.rotate( angle, expand=1 )
  </code></pre>
  
  <p>Kindy help me how to convert this rotated_image to base64 string.</p>
  
  <p>here's the <code>dir()</code> of rotated_image:</p>
  
  <blockquote>
    <p>['_Image__transformer', '__doc__', '__getattr__', '__init__',
    '__module__', '__repr__', '_copy', '_dump', '_expand', '_makeself',
    '_new', 'category', 'convert', 'copy', 'crop', 'draft', 'filter',
    'format', 'format_description', 'fromstring', 'getbands', 'getbbox',
    'getcolors', 'getdata', 'getextrema', 'getim', 'getpalette',
    'getpixel', 'getprojection', 'histogram', 'im', 'info', 'load',
    'mode', 'offset', 'palette', 'paste', 'point', 'putalpha', 'putdata',
    'putpalette', 'putpixel', 'quantize', 'readonly', 'resize', 'rotate',
    'save', 'seek', 'show', 'size', 'split', 'tell', 'thumbnail',
    'tobitmap', 'tostring', 'transform', 'transpose', 'verify']</p>
  </blockquote>