Pillow/docs/releasenotes/4.3.0.rst

4.3.0
-----

Get One Channel From Image
==========================

New method :py:meth:`PIL.Image.Image.getchannel` added.
It returns single channel by index or name. For example,
``image.getchannel("A")`` will return alpha channel as separate image.
``getchannel`` should work up to 6 times faster than ``image.split()[0]``
in previous Pillow versions.


Partial Resampling
==================

Added new argument ``box`` for :py:meth:`PIL.Image.Image.resize`. This
argument defines a source rectangle from within the source image to be
resized.  This is very similar to the ``image.crop(box).resize(size)``
sequence except that ``box`` can be specified with subpixel accuracy.


Loading 16-bit TIFF Images
==========================

Pillow now can read 16-bit multichannel TIFF files including files
with alpha transparency. The image data is truncated to 8-bit
precision.


Performance
===========

This release contains several performance improvements:

* Many memory bandwidth-bounded operations such as crop, image allocation,
  conversion, split into bands and merging from bands are up to 2x faster.
* Upscaling of multichannel images (such as RGB) is accelerated by 5-10%
* JPEG loading is accelerated up to 15% and JPEG saving up to 20% when
  using a recent version of libjpeg-turbo.


Core Image API Changes
======================

These are internal functions that should not have been used by user
code, but they were accessible from the python layer.

Debugging code within ``Image.core.grabclipboard`` was removed. It had been
marked as ``will be removed in future versions`` since PIL. When enabled, it
identified the format of the clipboard data.

The ``PIL.Image.core.copy`` and ``PIL.Image.Image.im.copy2`` methods
have been removed.