Pillow/docs/releasenotes/2.8.0.rst

2.8.0
-----

Open HTTP response objects with Image.open
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

HTTP response objects returned from ``urllib2.urlopen(url)`` or
``requests.get(url, stream=True).raw`` are 'file-like' but do not support ``.seek()``
operations. As a result PIL was unable to open them as images, requiring a wrap in
``cStringIO`` or ``BytesIO``.

Now new functionality has been added to ``Image.open()`` by way of an ``.seek(0)`` check and
catch on exception :py:exc:`AttributeError` or :py:exc:`io.UnsupportedOperation`. If this is caught we
attempt to wrap the object using ``io.BytesIO`` (which will only work on buffer-file-like
objects).

This allows opening of files using both ``urllib2`` and ``requests``, e.g.::

    Image.open(urllib2.urlopen(url))
    Image.open(requests.get(url, stream=True).raw)

If the response uses content-encoding (compression, either gzip or deflate) then this
will fail as both the urllib2 and requests raw file object will produce compressed data
in that case. Using Content-Encoding on images is rather non-sensical as most images are
already compressed, but it can still happen.

For requests the work-around is to set the decode_content attribute on the raw object to
True::

    response = requests.get(url, stream=True)
    response.raw.decode_content = True
    image = Image.open(response.raw)