Pillow/docs/releasenotes/3.3.0.rst

3.3.0
-----

Libimagequant support
=====================

There is now support for using libimagequant as a higher quality
quantization option in ``Image.quantize()`` on Unix-like
platforms. This support requires building Pillow from source against
libimagequant. We cannot distribute binaries due to licensing
differences.


New Setup.py options
====================

There are two new options to control the ``build_ext`` task in ``setup.py``:

  * ``--debug`` dumps all of the directories and files that are
    checked when searching for libraries or headers when building the
    extensions.
  * ``--disable-platform-guessing`` removes many of the directories
    that are checked for libraries and headers for build systems or
    cross compilers that specify that information in via environment
    variables.


Resizing
========

Image resampling for 8-bit per channel images was rewritten using only integer
computings. This is faster on most platforms and doesn't introduce precision
errors on the wide range of scales. With other performance improvements, this
makes resampling 60% faster on average.

Color calculation for images in the ``LA`` mode on semitransparent pixels
was fixed.


Rotation
========

Rotation for angles divisible by 90 degrees now always uses transposition.
This greatly improves both quality and performance in this case.
Also, the bug with wrong image size calculation when rotating by 90 degrees
was fixed.


Image Metadata
==============

The return type for binary data in version 2 Exif and Tiff metadata
has been changed from a tuple of integers to bytes. This is a change
from the behavior since ``3.0.0``.