split_archive.py

#!/usr/bin/env python3
import sys
import os

jpg = sys.argv[1]
with open(jpg, "rb") as f:
    b = f.read()
start_of_archive = b.find(b"\xff\xd9") + 2
out_fname = os.path.splitext(jpg)[0] + ".zip"
with open(out_fname, "wb") as f:
    f.write(b[start_of_archive:])