title: Photo Failed to manipulate with MiniMagick, maybe it is not an image? error
body: <p>I have the following code, which resizes and image and then adds some hex background. On localhost this works, but on heroku i get the following error</p>
  
  <pre><code>version :big do
    process :offer_resize_and_pad
   end
  
  def offer_resize_and_pad
    img = resize_and_pad(600, nil, model.hex, 'Center')
    img
  end
  </code></pre>
  
  <p><code>"Photo Failed to manipulate with MiniMagick, maybe it is not an image? Original Error: Command (\"mogrify -thumbnail \"600x&gt;\" -background \"#fff\" -gravity \"Center\" -extent \"600x\" /tmp/mini_magick20130217-2-1hts61y.jpg\") failed: {:status_code=&gt;1, :output=&gt;\"mogrify: Empty JPEG image (DNL not supported)</code>/tmp/mini_magick20130217-2-1hts61y.jpg' @ jpeg.c/EmitMessage/232.\n\"</p>