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Switch to using pillow for png as well.
The version check in _has_pil (pillow>=3.4) was dropped as the oldest Pillow that supports Py3.6 (the oldest Python supported by Matplotlib) is 4.0 anyways. Some complications arise from an unfortunate design decision that imread() returns pngs in 0-1 float dtype but others formats in integer dtype (via Pillow), and from Pillow having not-so-great support for 16-bit images (e.g. Pillow#3041). This makes reading of 16-bit RGB(A) PNGs (which are exposed as 0-1 floats by imread()) slightly less accurate, because Pillow coarsens them to 8-bit first (by truncation); hence the slight change in the pngsuite.png baseline image. (Note that the *renderers* only have 8-bit precision anyways (unless using mplcairo with cairo master...), but the discrepancy comes from differences in rounding between Pillow and Matplotlib).
1 parent 418984d commit 5f9d583

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‎.appveyor.yml

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@@ -60,7 +60,7 @@ install:
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# if conda-forge gets a new pyqt, it might be nice to install it as well to have more backends
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# https://github.com/conda-forge/conda-forge.github.io/issues/157#issuecomment-223536381
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- conda create -q -n test-environment python=%PYTHON_VERSION%
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freetype=2.6 "libpng>=1.6.21,<1.7" zlib=1.2 tk=8.5
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freetype=2.6 zlib=1.2 tk=8.5
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pip setuptools numpy sphinx tornado
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- activate test-environment
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- echo %PYTHON_VERSION% %TARGET_ARCH%
@@ -81,11 +81,9 @@ test_script:
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# Now build the thing..
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- set LINK=/LIBPATH:%cd%\lib
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- pip install -ve .
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# these should show no z, png, or freetype dll...
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# these should show no z or freetype dll...
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- set "DUMPBIN=%VS140COMNTOOLS%\..\..\VC\bin\dumpbin.exe"
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- 'if x%MPLSTATICBUILD% == xTrue "%DUMPBIN%" /DEPENDENTS lib\matplotlib\ft2font*.pyd | findstr freetype.*.dll && exit /b 1 || exit /b 0'
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- 'if x%MPLSTATICBUILD% == xTrue "%DUMPBIN%" /DEPENDENTS lib\matplotlib\_png*.pyd | findstr z.*.dll && exit /b 1 || exit /b 0'
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- 'if x%MPLSTATICBUILD% == xTrue "%DUMPBIN%" /DEPENDENTS lib\matplotlib\_png*.pyd | findstr png.*.dll && exit /b 1 || exit /b 0'
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# this are optional dependencies so that we don't skip so many tests...
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- if x%TEST_ALL% == xyes conda install -q ffmpeg inkscape miktex pillow

‎INSTALL.rst

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@@ -99,7 +99,7 @@ toolchain is prefixed. This may be used for cross compiling. ::
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export PKG_CONFIG=x86_64-pc-linux-gnu-pkg-config
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Once you have satisfied the requirements detailed below (mainly
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Python, NumPy, libpng and FreeType), you can build Matplotlib.
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Python, NumPy, and FreeType), you can build Matplotlib.
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::
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cd matplotlib
@@ -121,7 +121,6 @@ Matplotlib requires the following dependencies:
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* `Python <https://www.python.org/downloads/>`_ (>= 3.6)
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* `FreeType <https://www.freetype.org/>`_ (>= 2.3)
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* `libpng <http://www.libpng.org>`_ (>= 1.2)
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* `NumPy <http://www.numpy.org>`_ (>= 1.11)
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* `setuptools <https://setuptools.readthedocs.io/en/latest/>`_
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* `cycler <http://matplotlib.org/cycler/>`_ (>= 0.10.0)
@@ -177,8 +176,8 @@ etc., you can install the following:
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.. _pkg-config: https://www.freedesktop.org/wiki/Software/pkg-config/
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If not using pkg-config (in particular on Windows), you may need to set the
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include path (to the FreeType, libpng, and zlib headers) and link path (to
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the FreeType, libpng, and zlib libraries) explicitly, if they are not in
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include path (to the FreeType and zlib headers) and link path (to
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the FreeType and zlib libraries) explicitly, if they are not in
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standard locations. This can be done using standard environment variables
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-- on Linux and OSX:
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@@ -195,8 +194,8 @@ etc., you can install the following:
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set LINK=/LIBPATH:C:\directory\containing\freetype.lib ...
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where ``...`` means "also give, in the same format, the directories
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containing ``png.h`` and ``zlib.h`` for the include path, and for
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``libpng.so``/``png.lib`` and ``libz.so``/``z.lib`` for the link path."
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containing ``zlib.h`` for the include path, and for
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``libz.so``/``z.lib`` for the link path."
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.. note::
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@@ -237,20 +236,20 @@ Building on macOS
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-----------------
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The build situation on macOS is complicated by the various places one
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can get the libpng and FreeType requirements (MacPorts, Fink,
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can get FreeType (MacPorts, Fink,
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/usr/X11R6), the different architectures (e.g., x86, ppc, universal), and
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the different macOS versions (e.g., 10.4 and 10.5). We recommend that you build
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the way we do for the macOS release: get the source from the tarball or the
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git repository and install the required dependencies through a third-party
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package manager. Two widely used package managers are Homebrew, and MacPorts.
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The following example illustrates how to install libpng and FreeType using
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The following example illustrates how to install FreeType using
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``brew``::
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brew install libpng freetype pkg-config
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brew install freetype pkg-config
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If you are using MacPorts, execute the following instead::
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port install libpng freetype pkgconfig
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port install freetype pkgconfig
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After installing the above requirements, install Matplotlib from source by
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executing::
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for how to set up a build environment.
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Since there is no canonical Windows package manager, the methods for building
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FreeType, zlib, and libpng from source code are documented as a build script
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FreeType and zlib from source code are documented as a build script
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at `matplotlib-winbuild <https://github.com/jbmohler/matplotlib-winbuild>`_.
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There are a few possibilities to build Matplotlib on Windows:
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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This is a wheel build, but we use conda packages to get all the requirements.
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The binary requirements (png, FreeType,...) are statically linked and therefore
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not needed during the wheel install.
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FreeType is statically linked and therefore not needed during the wheel install.
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Set up the conda environment. Note, if you want a qt backend, add ``pyqt`` to
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the list of conda packages.
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::
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conda create -n "matplotlib_build" python=3.7 numpy python-dateutil pyparsing tornado cycler tk libpng zlib freetype
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conda create -n "matplotlib_build" python=3.7 numpy python-dateutil pyparsing tornado cycler tk zlib freetype
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conda activate matplotlib_build
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# force the build against static libpng and zlib libraries
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# force the build against static zlib libraries
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set MPLSTATICBUILD=True
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python setup.py bdist_wheel
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‎ci/azure-pipelines-steps.yml

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@@ -21,12 +21,8 @@ steps:
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displayName: 'Use latest available Nuget'
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- script: |
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nuget install libpng-msvc14-x64 -ExcludeVersion -OutputDirectory "$(build.BinariesDirectory)"
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nuget install zlib-msvc14-x64 -ExcludeVersion -OutputDirectory "$(build.BinariesDirectory)"
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echo ##vso[task.prependpath]$(build.BinariesDirectory)\libpng-msvc14-x64\build\native\bin_release
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echo ##vso[task.prependpath]$(build.BinariesDirectory)\zlib-msvc14-x64\build\native\bin_release
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echo ##vso[task.setvariable variable=CL]/I$(build.BinariesDirectory)\libpng-msvc14-x64\build\native\include /I$(build.BinariesDirectory)\zlib-msvc14-x64\build\native\include
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echo ##vso[task.setvariable variable=LINK]/LIBPATH:$(build.BinariesDirectory)\libpng-msvc14-x64\build\native\lib_release /LIBPATH:$(build.BinariesDirectory)\zlib-msvc14-x64\build\native\lib_release
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displayName: 'Install dependencies with nuget'
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‎doc/api/next_api_changes/2019-09-04-AL.rst

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@@ -0,0 +1,6 @@
1+
Matplotlib now uses Pillow to save and read pngs
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````````````````````````````````````````````````
3+
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The builtin png encoder and decoder has been removed, and Pillow is now a
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dependency. Note that when reading 16-bit RGB(A) images, Pillow truncates them
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to 8-bit precision, whereas the old builtin decoder kept the full precision.

‎doc/devel/min_dep_policy.rst

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@@ -60,7 +60,7 @@ minimum Python and numpy.
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System and C-dependencies
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=========================
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For system or c-dependencies (libpng, freetype, GUI frameworks, latex,
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For system or C-dependencies (FreeType, GUI frameworks, LaTeX,
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gs, ffmpeg) support as old as practical. These can be difficult to
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install for end-users and we want to be usable on as many systems as
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possible. We will bump these on a case-by-case basis.

‎lib/matplotlib/animation.py

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class PillowWriter(MovieWriter):
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@classmethod
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def isAvailable(cls):
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try:
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import PIL
548-
except ImportError:
549-
return False
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return True
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def __init__(self, *args, **kwargs):

‎lib/matplotlib/backend_bases.py

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from matplotlib.transforms import Affine2D
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from matplotlib.path import Path
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56-
try:
57-
from PIL import PILLOW_VERSION
58-
from distutils.version import LooseVersion
59-
if LooseVersion(PILLOW_VERSION) >= "3.4":
60-
_has_pil = True
61-
else:
62-
_has_pil = False
63-
del PILLOW_VERSION
64-
except ImportError:
65-
_has_pil = False
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_log = logging.getLogger(__name__)
68-
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_default_filetypes = {
70-
'ps': 'Postscript',
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'eps': 'Encapsulated Postscript',
60+
'jpg': 'Joint Photographic Experts Group',
61+
'jpeg': 'Joint Photographic Experts Group',
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'pdf': 'Portable Document Format',
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'pgf': 'PGF code for LaTeX',
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'png': 'Portable Network Graphics',
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'ps': 'Postscript',
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'raw': 'Raw RGBA bitmap',
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'rgba': 'Raw RGBA bitmap',
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'svg': 'Scalable Vector Graphics',
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'svgz': 'Scalable Vector Graphics'
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'svgz': 'Scalable Vector Graphics',
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'tif': 'Tagged Image File Format',
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'tiff': 'Tagged Image File Format',
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}
80-
81-
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_default_backends = {
83-
'ps': 'matplotlib.backends.backend_ps',
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'eps': 'matplotlib.backends.backend_ps',
75+
'jpg': 'matplotlib.backends.backend_agg',
76+
'jpeg': 'matplotlib.backends.backend_agg',
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'pdf': 'matplotlib.backends.backend_pdf',
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'pgf': 'matplotlib.backends.backend_pgf',
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'png': 'matplotlib.backends.backend_agg',
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'ps': 'matplotlib.backends.backend_ps',
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'raw': 'matplotlib.backends.backend_agg',
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'rgba': 'matplotlib.backends.backend_agg',
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'svg': 'matplotlib.backends.backend_svg',
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'svgz': 'matplotlib.backends.backend_svg',
85+
'tif': 'matplotlib.backends.backend_agg',
86+
'tiff': 'matplotlib.backends.backend_agg',
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}
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@@ -1604,17 +1599,6 @@ class FigureCanvasBase:
16041599
fixed_dpi = None
16051600

16061601
filetypes = _default_filetypes
1607-
if _has_pil:
1608-
# JPEG support
1609-
register_backend('jpg', 'matplotlib.backends.backend_agg',
1610-
'Joint Photographic Experts Group')
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register_backend('jpeg', 'matplotlib.backends.backend_agg',
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'Joint Photographic Experts Group')
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# TIFF support
1614-
register_backend('tif', 'matplotlib.backends.backend_agg',
1615-
'Tagged Image File Format')
1616-
register_backend('tiff', 'matplotlib.backends.backend_agg',
1617-
'Tagged Image File Format')
16181602

16191603
@cbook._classproperty
16201604
def supports_blit(cls):

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