我正在使用userena，我猜我没有安装正确的编码器（我猜测它是不是？）每当我尝试上传个人资料图片时，就会出现以下错误。我该如何解决这个问题？
IOError at /accounts/billy/edit/
decoder jpeg not available
Request Method: POST
Request URL: http://127.0.0.1:8000/accounts/billy/edit/
Django Version: 1.6
Exception Type: IOError
Exception Value:
decoder jpeg not available
Exception Location: /home/ben/Documents/proj/local/lib/python2.7/site-packages /PIL/Image.py in _getdecoder