Python 3
import base64
from io import BytesIO
buffered = BytesIO()
image.save(buffered, format="JPEG")
img_str = base64.b64encode(buffered.getvalue())
Python 2
import base64
import cStringIO
buffer = cStringIO.StringIO()
image.save(buffer, format="JPEG")
img_str = base64.b64encode(buffer.getvalue())