from flask import send_file
from io import BytesIO
ls_f = redi.get(photo)
ls_f1 = base64.b64decode(ls_f)
#将字符流写入BytesIO(主要用于读取缓存中的数据)
by = BytesIO(ls_f1)
return send_file(by, mimetype=‘image/png‘)
原文：http://www.cnblogs.com/wuqingzangyue/p/5749811.html