How to convert base64 string to a PIL Image object

import base64
from PIL import Image

def img_to_txt(img):
    msg = ""
    msg = msg + "<plain_txt_msg:img>"
    with open(img, "rb") as imageFile:
        msg = msg + str(base64.b64encode(imageFile.read()))
    msg = msg + "<!plain_txt_msg>"

    return msg

class decode:
    def decode_img(msg):
        img = msg[msg.find(
        "<plain_txt_msg:img>"):msg.find(<!plain_txt_msg>")]
        #how do I convert the str 'img', encoded in base64, to a PIL Image?

while 1:
    decode.decode_img(img_to_txt(input()))

How do I convert the string to a PIL Image object, I was thinking of using the function frombytes() withing the Image module from PIL.