BUG: unpin Pillow and allow versions >=10.1.0 (#1045)

imageio/plugins/pillow.py

@@ -34,13 +34,18 @@
 from typing import Any, Callable, Dict, Iterator, List, Optional, Tuple, Union, cast
 
 import numpy as np
-from PIL import ExifTags, GifImagePlugin, Image, ImageSequence, UnidentifiedImageError  # type: ignore
+from PIL import ExifTags, GifImagePlugin, Image, ImageSequence, UnidentifiedImageError
+from PIL import __version__ as pil_version  # type: ignore
 
 from ..core.request import URI_BYTES, InitializationError, IOMode, Request
 from ..core.v3_plugin_api import ImageProperties, PluginV3
 from ..typing import ArrayLike
 
 
+def pillow_version() -> Tuple[int]:
+    return tuple(int(x) for x in pil_version.split("."))
+
+
 def _exif_orientation_transform(orientation: int, mode: str) -> Callable:
     # get transformation that transforms an image from a
     # given EXIF orientation into the standard orientation
@@ -303,29 +308,27 @@ def _apply_transforms(
             # see: https://github.com/python-pillow/Pillow/issues/5929
             image = image.convert(image.palette.mode)
         elif image.format == "PNG" and image.mode == "I":
-            # By default, pillows unpacks 16-bit grayscale PNG into 32-bit
-            # integers due to limited 16-bit support in pillow itself. However,
-            # recent versions can directly unpack into a 16-bit buffer, which is
-            # more correct (and more efficient) in our scenario.
+            major, minor, patch = pillow_version()
 
             if sys.byteorder == "little":
                 desired_mode = "I;16"
             else:  # pragma: no cover
                 # can't test big-endian in GH-Actions
                 desired_mode = "I;16B"
 
-            try:
-                Image._getdecoder(desired_mode, "raw", "I;16B")
-            except ValueError:
+            if major < 10:  # pragma: no cover
                 warnings.warn(
                     "Loading 16-bit (uint16) PNG as int32 due to limitations "
                     "in pillow's PNG decoder. This will be fixed in a future "
                     "version of pillow which will make this warning dissapear.",
                     UserWarning,
                 )
-            else:  # pragma: no cover
-                # Let pillow know that it is okay to return 16-bit
+            elif minor < 1:  # pragma: no cover
+                # pillow<10.1.0 can directly decode into 16-bit grayscale
                 image.mode = desired_mode
+            else:
+                # pillow >= 10.1.0
+                image = image.convert(desired_mode)
 
         image = np.asarray(image)
 

imageio/plugins/pillowmulti.py

@@ -6,8 +6,7 @@
 
 import numpy as np
 
-from .pillow_legacy import PillowFormat, ndarray_to_pil, image_as_uint
-
+from .pillow_legacy import PillowFormat, image_as_uint, ndarray_to_pil
 
 logger = logging.getLogger(__name__)
 
@@ -27,7 +26,7 @@ class GIFFormat(PillowFormat):
 
     # GIF reader needs no modifications compared to base pillow reader
 
-    class Writer(PillowFormat.Writer):
+    class Writer(PillowFormat.Writer):  # pragma: no cover
         def _open(
             self,
             loop=0,
@@ -37,6 +36,16 @@ def _open(
             quantizer=0,
             subrectangles=False,
         ):
+            from PIL import __version__ as pillow_version
+
+            major, minor, patch = tuple(int(x) for x in pillow_version.split("."))
+            if major == 10 and minor >= 1:
+                raise ImportError(
+                    f"Pillow v{pillow_version} is not supported by ImageIO's legacy "
+                    "pillow plugin when writing GIF. Consider using to the new "
+                    "plugin or downgrade to `pillow<10.1.0`."
+                )
+
             # Check palettesize
             palettesize = int(palettesize)
             if palettesize < 2 or palettesize > 256:
@@ -89,7 +98,7 @@ def intToBin(i):
     return i.to_bytes(2, byteorder="little")
 
 
-class GifWriter:
+class GifWriter:  # pragma: no cover
     """Class that for helping write the animated GIF file. This is based on
     code from images2gif.py (part of visvis). The version here is modified
     to allow streamed writing.

setup.py

@@ -83,7 +83,7 @@
 
 # pinned to > 8.3.2 due to security vulnerability
 # See: https://github.com/advisories/GHSA-98vv-pw6r-q6q4
-install_requires = ["numpy", "pillow>= 8.3.2,<10.1.0"]
+install_requires = ["numpy", "pillow>= 8.3.2"]
 
 plugins = {
     "bsdf": [],

tests/test_legacy_plugin_wrapper.py

@@ -1,6 +1,5 @@
 import imageio as iio
 import pytest
-import numpy as np
 
 
 def test_exception_message_bytes():
@@ -42,16 +41,6 @@ def test_ellipsis_index(test_images):
     assert metadata == {}
 
 
-def test_list_writing(test_images, tmp_path):
-    expected = iio.v3.imread(test_images / "newtonscradle.gif", index=...)
-    expected = [*expected]
-
-    iio.v3.imwrite(tmp_path / "test.gif", expected, plugin="GIF-PIL")
-    actual = iio.v3.imread(tmp_path / "test.gif", index=...)
-
-    assert np.allclose(actual, expected)
-
-
 def test_properties(test_images):
     p = iio.v3.improps(test_images / "newtonscradle.gif", plugin="GIF-PIL", index=...)
     assert p.shape == (36, 150, 200, 4)

tests/test_pillow_legacy.py

@@ -277,7 +277,12 @@ def test_gif(tmp_path):
                     continue  # quantize fails, see also png
                 fname = fnamebase + "%i.%i.%i.gif" % (isfloat, crop, colors)
                 rim = get_ref_im(colors, crop, isfloat)
-                imageio.imsave(fname, rim, format="GIF-PIL")
+
+                try:
+                    imageio.imsave(fname, rim, format="GIF-PIL")
+                except ImportError:
+                    pytest.xfail("New pillow version is no longer supported.")
+
                 im = imageio.imread(fname, format="GIF-PIL")
                 mul = 255 if isfloat else 1
                 if colors not in (0, 1):
@@ -321,7 +326,10 @@ def test_animated_gif(test_images, tmp_path):
                 ims1 = [x.astype(np.float32) / 256 for x in ims1]
             ims1 = [x[:, :, :colors] for x in ims1]
             fname = fnamebase + ".animated.%i.gif" % colors
-            imageio.mimsave(fname, ims1, duration=0.2, format="GIF-PIL")
+            try:
+                imageio.mimsave(fname, ims1, duration=0.2, format="GIF-PIL")
+            except ImportError:
+                pytest.xfail("Pillow version no longer supported.")
             # Retrieve
             print("fooo", fname, isfloat, colors)
             ims2 = imageio.mimread(fname, format="GIF-PIL")