title: Cropping image in Django causes substantial memory increase
body: <p>I've recently run into a problem with my Django project and memory usage on WebFaction.</p>
  
  <p>Here is the two processes running in memory for this project on webfaction:</p>
  
  <pre><code>30396  4-20:20:00 13486 
  30404  4-20:20:00 13487 
  </code></pre>
  
  <p>After the view is run one of the processes will increase substantially:</p>
  
  <pre><code>69720  4-20:20:22 13486 
  30404  4-20:20:22 13487 
  </code></pre>
  
  <p>As you can see the first process more than doubled in memory usage!  As this function will be used often I need to figure out what is happening.  I believe I've narrowed it down to the following view (it's a 3 step process to upload an image, add details, crop a thumbnail).</p>
  
  <p>Here is the view below.  It gets a photo object, loads the image from the file, gets the box coordinates that the user has submitted and then creates a 200,200 sized image.  This newly created image is written back to the disk with a .thumbnail in the filename and the photo object is saved.</p>
  
  <pre><code>@login_required
  def upload3(request, photo_pk):
      photo = get_object_or_404(Photo, pk=photo_pk, user=request.user)
      if request.method == "POST":
          form = upload3Form(request.POST)
          if form.is_valid():
              im = Image.open(photo.image.path)
              try:
                  box =(form.cleaned_data['x1'],form.cleaned_data['y1'],form.cleaned_data['x2'],form.cleaned_data['y2'])
              except:
                  box = ('0','0','1000','1000')
              cropped = im.crop(box)
              cropped.thumbnail((200,200),Image.ANTIALIAS)
              result = os.path.splitext(photo.image.path)
              cropped.save(result[0] + '.thumbnail' + result[1])
              photo.status = 3
              photo.save()
  </code></pre>
  
  <p>Any ideas of what I may be doing wrong would be greatly appreciated. </p>
  
  <p><code>Update 1</code>:  Images used for testing are all Jpeg and have dimensions around 3600 x 2700 and are around 2 MB per image.</p>