gistfile1.py

import io
from PIL import Image
from PIL import TiffImagePlugin

im = Image.open('tmp/test/in/1900-1910/00/joey.jpg')
exif = im._getexif()

data = im.info["exif"]
file = io.BytesIO(data[6:])
head = file.read(8)
info = TiffImagePlugin.ImageFileDirectory(head)
info.load(file)
print info.items()

# modify orientation
info[0x0112] = (8,)
out = io.BytesIO()
info.save(out)
out.seek(0)
dat = out.read()

im.info["exif"] = data[:14] + dat + data[exif[0x8769]:]
im.save('tmp.jpg')