Pillow/docs/releasenotes/10.2.0.rst

10.2.0
------

Security
========

ImageFont.getmask: Applied ImageFont.MAX_STRING_LENGTH
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

To protect against potential DOS attacks when using arbitrary strings as text input,
Pillow will now raise a :py:exc:`ValueError` if the number of characters passed into
:py:meth:`PIL.ImageFont.ImageFont.getmask` is over a certain limit,
:py:data:`PIL.ImageFont.MAX_STRING_LENGTH`.

This threshold can be changed by setting :py:data:`PIL.ImageFont.MAX_STRING_LENGTH`. It
can be disabled by setting ``ImageFont.MAX_STRING_LENGTH = None``.

A decompression bomb check has also been added to
:py:meth:`PIL.ImageFont.ImageFont.getmask`.

ImageFont.getmask: Trim glyph size
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

To protect against potential DOS attacks when using PIL fonts,
:py:class:`PIL.ImageFont.ImageFont` now trims the size of individual glyphs so that
they do not extend beyond the bitmap image.

:cve:`2023-50447`: ImageMath.eval: Restricted environment keys
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

If an attacker has control over the keys passed to the
``environment`` argument of :py:meth:`PIL.ImageMath.eval`, they may be able to execute
arbitrary code. To prevent this, keys matching the names of builtins and keys
containing double underscores will now raise a :py:exc:`ValueError`.

Deprecations
============

ImageFile.raise_oserror
^^^^^^^^^^^^^^^^^^^^^^^

``ImageFile.raise_oserror()`` has been deprecated and will be removed in Pillow
12.0.0 (2025-10-15). The function is undocumented and is only useful for translating
error codes returned by a codec's ``decode()`` method, which ImageFile already does
automatically.

IptcImageFile helper functions
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The functions ``IptcImageFile.dump`` and ``IptcImageFile.i``, and the constant
``IptcImageFile.PAD`` have been deprecated and will be removed in Pillow
12.0.0 (2025-10-15). These are undocumented helper functions intended
for internal use, so there is no replacement. They can each be replaced
by a single line of code using builtin functions in Python.

API Changes
===========

Zero or negative font size error
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

When creating a :py:class:`~PIL.ImageFont.FreeTypeFont` instance, either directly or
through :py:func:`~PIL.ImageFont.truetype`, if the font size is zero or less, a
:py:exc:`ValueError` will now be raised.

API Additions
=============

Added DdsImagePlugin enums
^^^^^^^^^^^^^^^^^^^^^^^^^^

:py:class:`~PIL.DdsImagePlugin.DDSD`, :py:class:`~PIL.DdsImagePlugin.DDSCAPS`,
:py:class:`~PIL.DdsImagePlugin.DDSCAPS2`, :py:class:`~PIL.DdsImagePlugin.DDPF`,
:py:class:`~PIL.DdsImagePlugin.DXGI_FORMAT` and :py:class:`~PIL.DdsImagePlugin.D3DFMT`
enums have been added to :py:class:`PIL.DdsImagePlugin`.

JPEG RGB color space
^^^^^^^^^^^^^^^^^^^^

When saving JPEG files, ``keep_rgb`` can now be set to ``True``. This will store RGB
images in the RGB color space instead of being converted to YCbCr automatically by
libjpeg. When this option is enabled, attempting to chroma-subsample RGB images with
the ``subsampling`` option will raise an :py:exc:`OSError`.

JPEG restart marker interval
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

When saving JPEG files, ``restart_marker_blocks`` and ``restart_marker_rows`` can now
be used to emit restart markers whenever the specified number of MCU blocks or rows
have been produced.

JPEG tables-only streamtype
^^^^^^^^^^^^^^^^^^^^^^^^^^^

When saving JPEG files, ``streamtype`` can now be set to 1, for tables-only. This will
output only the quantization and Huffman tables for the image.

Other Changes
=============

Added DDS BC4U and DX10 BC1 and BC4 reading
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Support has been added to read the BC4U format of DDS images.

Support has also been added to read DX10 BC1 and BC4, whether UNORM or
TYPELESS.

Support arbitrary masks for uncompressed RGB DDS images
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

All masks are now supported when reading DDS images with uncompressed RGB data,
allowing for bit counts other than 24 and 32.

Saving TIFF tag RowsPerStrip
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

When saving TIFF images, the TIFF tag RowsPerStrip can now be one of the tags set by
the user, rather than always being calculated by Pillow.

Optimized ImageColor.getrgb and getcolor
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The color calculations of :py:attr:`~PIL.ImageColor.getrgb` and
:py:attr:`~PIL.ImageColor.getcolor` are now cached using
:py:func:`functools.lru_cache`. Cached calls of ``getrgb`` are 3.1 - 91.4 times
as fast and ``getcolor`` are 5.1 - 19.6 times as fast.

Optimized ImageMode.getmode
^^^^^^^^^^^^^^^^^^^^^^^^^^^

The lookups made by :py:attr:`~PIL.ImageMode.getmode` are now cached using
:py:func:`functools.lru_cache` instead of a custom cache. Cached calls are 1.2 times as
fast.

Optimized ImageStat.Stat count and extrema
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Calculating the :py:attr:`~PIL.ImageStat.Stat.count` and
:py:attr:`~PIL.ImageStat.Stat.extrema` statistics is now faster. After the
histogram is created in ``st = ImageStat.Stat(im)``, ``st.count`` is 3 times as fast on
average and ``st.extrema`` is 12 times as fast on average.

Encoder errors now report error detail as string
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

:py:exc:`OSError` exceptions from image encoders now include a textual description of
the error instead of a numeric error code.

Type hints
^^^^^^^^^^

Work has begun to add type annotations to Pillow, including:

* :py:mod:`~PIL.ContainerIO`
* :py:mod:`~PIL.FontFile`, :py:mod:`~PIL.BdfFontFile` and :py:mod:`~PIL.PcfFontFile`
* :py:mod:`~PIL.ImageChops`
* :py:mod:`~PIL.ImageMode`
* :py:mod:`~PIL.ImageSequence`
* :py:mod:`~PIL.ImageTransform`
* :py:mod:`~PIL.TarIO`