Pillow/docs/releasenotes/9.1.0.rst

9.1.0
-----

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

Raise an error when performing a negative crop
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Performing a negative crop on an image previously just returned a ``(0, 0)`` image. Now
it will raise a :py:exc:`ValueError`, to help reduce confusion if a user has unintentionally
provided the wrong arguments.

Added specific error if path coordinate type is incorrect
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Rather than returning a :py:exc:`SystemError`, passing the incorrect types of coordinates into
a path will now raise a more specific :py:exc:`ValueError`, with the message "incorrect
coordinate type".

Replace requirements.txt with extras
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Rather than installing all dependencies for docs and tests via ``requirements.txt``,
``extras_require`` is used instead. This installs only those needed and at the same
time as installing Pillow.

For example:

.. code-block:: bash

    # Install with dependencies for tests:
    python3 -m pip install .[tests]

    # Or for building docs:
    python3 -m pip install .[docs]

    # Or for all:
    python3 -m pip install .[docs,tests]

On macOS, the last argument may need to be wrapped in quotes, e.g.
``python3 -m pip install ".[tests]"``

Therefore ``requirements.txt`` has been removed along with the ``make install-req``
command for installing its contents.

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

Constants
^^^^^^^^^

A number of constants have been deprecated and will be removed in Pillow 10.0.0
(2023-07-01). Instead, :py:class:`enum.IntEnum` classes have been added.

.. note::

    Some of these deprecations were restored in Pillow 9.4.0. See
    :ref:`restored-image-constants`

=====================================================  ============================================================
Deprecated                                             Use instead
=====================================================  ============================================================
``Image.NONE``                                         Either ``Image.Dither.NONE`` or ``Image.Resampling.NEAREST``
``Image.NEAREST``                                      Either ``Image.Dither.NONE`` or ``Image.Resampling.NEAREST``
``Image.ORDERED``                                      ``Image.Dither.ORDERED``
``Image.RASTERIZE``                                    ``Image.Dither.RASTERIZE``
``Image.FLOYDSTEINBERG``                               ``Image.Dither.FLOYDSTEINBERG``
``Image.WEB``                                          ``Image.Palette.WEB``
``Image.ADAPTIVE``                                     ``Image.Palette.ADAPTIVE``
``Image.AFFINE``                                       ``Image.Transform.AFFINE``
``Image.EXTENT``                                       ``Image.Transform.EXTENT``
``Image.PERSPECTIVE``                                  ``Image.Transform.PERSPECTIVE``
``Image.QUAD``                                         ``Image.Transform.QUAD``
``Image.MESH``                                         ``Image.Transform.MESH``
``Image.FLIP_LEFT_RIGHT``                              ``Image.Transpose.FLIP_LEFT_RIGHT``
``Image.FLIP_TOP_BOTTOM``                              ``Image.Transpose.FLIP_TOP_BOTTOM``
``Image.ROTATE_90``                                    ``Image.Transpose.ROTATE_90``
``Image.ROTATE_180``                                   ``Image.Transpose.ROTATE_180``
``Image.ROTATE_270``                                   ``Image.Transpose.ROTATE_270``
``Image.TRANSPOSE``                                    ``Image.Transpose.TRANSPOSE``
``Image.TRANSVERSE``                                   ``Image.Transpose.TRANSVERSE``
``Image.BOX``                                          ``Image.Resampling.BOX``
``Image.BILINEAR``                                     ``Image.Resampling.BILINEAR``
``Image.LINEAR``                                       ``Image.Resampling.BILINEAR``
``Image.HAMMING``                                      ``Image.Resampling.HAMMING``
``Image.BICUBIC``                                      ``Image.Resampling.BICUBIC``
``Image.CUBIC``                                        ``Image.Resampling.BICUBIC``
``Image.LANCZOS``                                      ``Image.Resampling.LANCZOS``
``Image.ANTIALIAS``                                    ``Image.Resampling.LANCZOS``
``Image.MEDIANCUT``                                    ``Image.Quantize.MEDIANCUT``
``Image.MAXCOVERAGE``                                  ``Image.Quantize.MAXCOVERAGE``
``Image.FASTOCTREE``                                   ``Image.Quantize.FASTOCTREE``
``Image.LIBIMAGEQUANT``                                ``Image.Quantize.LIBIMAGEQUANT``
``ImageCms.INTENT_PERCEPTUAL``                         ``ImageCms.Intent.PERCEPTUAL``
``ImageCms.INTENT_RELATIVE_COLORMETRIC``               ``ImageCms.Intent.RELATIVE_COLORMETRIC``
``ImageCms.INTENT_SATURATION``                         ``ImageCms.Intent.SATURATION``
``ImageCms.INTENT_ABSOLUTE_COLORIMETRIC``              ``ImageCms.Intent.ABSOLUTE_COLORIMETRIC``
``ImageCms.DIRECTION_INPUT``                           ``ImageCms.Direction.INPUT``
``ImageCms.DIRECTION_OUTPUT``                          ``ImageCms.Direction.OUTPUT``
``ImageCms.DIRECTION_PROOF``                           ``ImageCms.Direction.PROOF``
``ImageFont.LAYOUT_BASIC``                             ``ImageFont.Layout.BASIC``
``ImageFont.LAYOUT_RAQM``                              ``ImageFont.Layout.RAQM``
``BlpImagePlugin.BLP_FORMAT_JPEG``                     ``BlpImagePlugin.Format.JPEG``
``BlpImagePlugin.BLP_ENCODING_UNCOMPRESSED``           ``BlpImagePlugin.Encoding.UNCOMPRESSED``
``BlpImagePlugin.BLP_ENCODING_DXT``                    ``BlpImagePlugin.Encoding.DXT``
``BlpImagePlugin.BLP_ENCODING_UNCOMPRESSED_RAW_RGBA``  ``BlpImagePlugin.Encoding.UNCOMPRESSED_RAW_RGBA``
``BlpImagePlugin.BLP_ALPHA_ENCODING_DXT1``             ``BlpImagePlugin.AlphaEncoding.DXT1``
``BlpImagePlugin.BLP_ALPHA_ENCODING_DXT3``             ``BlpImagePlugin.AlphaEncoding.DXT3``
``BlpImagePlugin.BLP_ALPHA_ENCODING_DXT5``             ``BlpImagePlugin.AlphaEncoding.DXT5``
``FtexImagePlugin.FORMAT_DXT1``                        ``FtexImagePlugin.Format.DXT1``
``FtexImagePlugin.FORMAT_UNCOMPRESSED``                ``FtexImagePlugin.Format.UNCOMPRESSED``
``PngImagePlugin.APNG_DISPOSE_OP_NONE``                ``PngImagePlugin.Disposal.OP_NONE``
``PngImagePlugin.APNG_DISPOSE_OP_BACKGROUND``          ``PngImagePlugin.Disposal.OP_BACKGROUND``
``PngImagePlugin.APNG_DISPOSE_OP_PREVIOUS``            ``PngImagePlugin.Disposal.OP_PREVIOUS``
``PngImagePlugin.APNG_BLEND_OP_SOURCE``                ``PngImagePlugin.Blend.OP_SOURCE``
``PngImagePlugin.APNG_BLEND_OP_OVER``                  ``PngImagePlugin.Blend.OP_OVER``
=====================================================  ============================================================

ImageShow.Viewer.show_file file argument
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The ``file`` argument in :py:meth:`~PIL.ImageShow.Viewer.show_file()` has been
deprecated and  will be removed in Pillow 10.0.0 (2023-07-01). It has been replaced by
``path``.

In effect, ``viewer.show_file("test.jpg")`` will continue to work unchanged.
``viewer.show_file(file="test.jpg")`` will raise a deprecation warning, and suggest
``viewer.show_file(path="test.jpg")`` instead.

FitsStubImagePlugin
^^^^^^^^^^^^^^^^^^^

.. deprecated:: 9.1.0

The stub image plugin ``FitsStubImagePlugin`` has been deprecated and will be removed in
Pillow 10.0.0 (2023-07-01). FITS images can be read without a handler through
:mod:`~PIL.FitsImagePlugin` instead.

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

Added get_photoshop_blocks() to parse Photoshop TIFF tag
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

:py:meth:`~PIL.TiffImagePlugin.TiffImageFile.get_photoshop_blocks` has been added, to
allow users to determine what Photoshop "Image Resource Blocks" are contained within an
image. The keys of the returned dictionary are the image resource IDs.

At present, the information within each block is merely returned as a dictionary with a
"data" entry. This will allow more useful information to be added in the future without
breaking backwards compatibility.

Added mct and no_jp2 options for saving JPEG 2000
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The :py:meth:`PIL.Image.Image.save` method now supports the following options for
JPEG 2000:

**mct**
    If ``1`` then enable multiple component transformation when encoding,
    otherwise use ``0`` for no component transformation (default). If MCT is
    enabled and ``irreversible`` is ``True`` then the Irreversible Color
    Transformation will be applied, otherwise encoding will use the
    Reversible Color Transformation. MCT works best with a ``mode`` of
    ``RGB`` and is only applicable when the image data has 3 components.

**no_jp2**
    If ``True`` then don't wrap the raw codestream in the JP2 file format when
    saving, otherwise the extension of the filename will be used to determine
    the format (default).

Added PyEncoder
^^^^^^^^^^^^^^^

:py:class:`~PIL.ImageFile.PyEncoder` has been added, allowing for file encoders to be
written in Python. See :ref:`Writing Your Own File Codec in Python<file-codecs-py>` for
more information.

GifImagePlugin loading strategy
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Pillow 9.0.0 introduced the conversion of subsequent GIF frames to ``RGB`` or ``RGBA``. This
behaviour can now be changed so that the first ``P`` frame is converted to ``RGB`` as
well. ::

    from PIL import GifImagePlugin
    GifImagePlugin.LOADING_STRATEGY = GifImagePlugin.LoadingStrategy.RGB_ALWAYS

Or subsequent frames can be kept in ``P`` mode as long as there is only a single
palette. ::

    from PIL import GifImagePlugin
    GifImagePlugin.LOADING_STRATEGY = GifImagePlugin.LoadingStrategy.RGB_AFTER_DIFFERENT_PALETTE_ONLY

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

musllinux wheels
^^^^^^^^^^^^^^^^

Pillow now builds binary wheels for musllinux, suitable for Linux distributions based on the musl C standard library such as Alpine
(rather than the glibc library used by manylinux wheels). See :pep:`656`.

ImageShow temporary files on Unix
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

When calling :py:meth:`~PIL.Image.Image.show` or using :py:mod:`~PIL.ImageShow`,
a temporary file is created from the image. On Unix, Pillow will no longer delete these
files, and instead leave it to the operating system to do so.

Image._repr_pretty_
^^^^^^^^^^^^^^^^^^^

``im._repr_pretty_`` has been added to provide a representation of an image without the
identity of the object. This allows Jupyter to describe an image and have that
description stay the same on subsequent executions of the same code.

Added BigTIFF reading
^^^^^^^^^^^^^^^^^^^^^

Support has been added for reading BigTIFF images.

Added BLP saving
^^^^^^^^^^^^^^^^

Support has been added for saving BLP images. ``blp_version`` can be used to specify
whether the image should be saved as BLP1 or BLP2, e.g.
``im.save("out.blp", blp_version="BLP1")``. By default, BLP2 will be used.