Added type hints to ImageFilter

Tests/test_color_lut.py

@@ -354,10 +354,10 @@ class TestColorLut3DCoreAPI:
 class TestColorLut3DFilter:
     def test_wrong_args(self) -> None:
         with pytest.raises(ValueError, match="should be either an integer"):
-            ImageFilter.Color3DLUT("small", [1])
+            ImageFilter.Color3DLUT("small", [1])  # type: ignore[arg-type]
 
         with pytest.raises(ValueError, match="should be either an integer"):
-            ImageFilter.Color3DLUT((11, 11), [1])
+            ImageFilter.Color3DLUT((11, 11), [1])  # type: ignore[arg-type]
 
         with pytest.raises(ValueError, match=r"in \[2, 65\] range"):
             ImageFilter.Color3DLUT((11, 11, 1), [1])

Tests/test_image_filter.py

@@ -137,7 +137,7 @@ def test_builtinfilter_p() -> None:
     builtin_filter = ImageFilter.BuiltinFilter()
 
     with pytest.raises(ValueError):
-        builtin_filter.filter(hopper("P"))
+        builtin_filter.filter(hopper("P").im)
 
 
 def test_kernel_not_enough_coefficients() -> None:

Tests/test_numpy.py

@@ -1,17 +1,17 @@
 from __future__ import annotations
 
 import warnings
-from typing import TYPE_CHECKING, Any
+from typing import TYPE_CHECKING
 
 import pytest
 
-from PIL import Image
+from PIL import Image, _typing
 
 from .helper import assert_deep_equal, assert_image, hopper, skip_unless_feature
 
 if TYPE_CHECKING:
     import numpy
-    import numpy.typing
+    import numpy.typing as npt
 else:
     numpy = pytest.importorskip("numpy", reason="NumPy not installed")
 
@@ -19,9 +19,7 @@ TEST_IMAGE_SIZE = (10, 10)
 
 
 def test_numpy_to_image() -> None:
-    def to_image(
-        dtype: numpy.typing.DTypeLike, bands: int = 1, boolean: int = 0
-    ) -> Image.Image:
+    def to_image(dtype: npt.DTypeLike, bands: int = 1, boolean: int = 0) -> Image.Image:
         if bands == 1:
             if boolean:
                 data = [0, 255] * 50
@@ -106,9 +104,7 @@ def test_1d_array() -> None:
     assert_image(Image.fromarray(a), "L", (1, 5))
 
 
-def _test_img_equals_nparray(
-    img: Image.Image, np_img: numpy.typing.NDArray[Any]
-) -> None:
+def _test_img_equals_nparray(img: Image.Image, np_img: _typing.NumpyArray) -> None:
     assert len(np_img.shape) >= 2
     np_size = np_img.shape[1], np_img.shape[0]
     assert img.size == np_size
@@ -166,7 +162,7 @@ def test_save_tiff_uint16() -> None:
         ("HSV", numpy.uint8),
     ),
 )
-def test_to_array(mode: str, dtype: numpy.typing.DTypeLike) -> None:
+def test_to_array(mode: str, dtype: npt.DTypeLike) -> None:
     img = hopper(mode)
 
     # Resize to non-square
@@ -216,7 +212,7 @@ def test_putdata() -> None:
         numpy.float64,
     ),
 )
-def test_roundtrip_eye(dtype: numpy.typing.DTypeLike) -> None:
+def test_roundtrip_eye(dtype: npt.DTypeLike) -> None:
     arr = numpy.eye(10, dtype=dtype)
     numpy.testing.assert_array_equal(arr, numpy.array(Image.fromarray(arr)))
 

docs/reference/internal_modules.rst

@@ -33,6 +33,10 @@ Internal Modules
 Provides a convenient way to import type hints that are not available
 on some Python versions.
 
+.. py:class:: NumpyArray
+
+    Typing alias.
+
 .. py:class:: StrOrBytesPath
 
     Typing alias.

src/PIL/ImageFilter.py

@@ -19,12 +19,16 @@ from __future__ import annotations
 import abc
 import functools
 from types import ModuleType
-from typing import Any, Sequence
+from typing import TYPE_CHECKING, Any, Callable, Sequence, cast
+
+if TYPE_CHECKING:
+    from . import _imaging
+    from ._typing import NumpyArray
 
 
 class Filter:
     @abc.abstractmethod
-    def filter(self, image):
+    def filter(self, image: _imaging.ImagingCore) -> _imaging.ImagingCore:
         pass
 
 
@@ -33,7 +37,9 @@ class MultibandFilter(Filter):
 
 
 class BuiltinFilter(MultibandFilter):
-    def filter(self, image):
+    filterargs: tuple[Any, ...]
+
+    def filter(self, image: _imaging.ImagingCore) -> _imaging.ImagingCore:
         if image.mode == "P":
             msg = "cannot filter palette images"
             raise ValueError(msg)
@@ -91,7 +97,7 @@ class RankFilter(Filter):
         self.size = size
         self.rank = rank
 
-    def filter(self, image):
+    def filter(self, image: _imaging.ImagingCore) -> _imaging.ImagingCore:
         if image.mode == "P":
             msg = "cannot filter palette images"
             raise ValueError(msg)
@@ -158,7 +164,7 @@ class ModeFilter(Filter):
     def __init__(self, size: int = 3) -> None:
         self.size = size
 
-    def filter(self, image):
+    def filter(self, image: _imaging.ImagingCore) -> _imaging.ImagingCore:
         return image.modefilter(self.size)
 
 
@@ -176,9 +182,9 @@ class GaussianBlur(MultibandFilter):
     def __init__(self, radius: float | Sequence[float] = 2) -> None:
         self.radius = radius
 
-    def filter(self, image):
+    def filter(self, image: _imaging.ImagingCore) -> _imaging.ImagingCore:
         xy = self.radius
-        if not isinstance(xy, (tuple, list)):
+        if isinstance(xy, (int, float)):
             xy = (xy, xy)
         if xy == (0, 0):
             return image.copy()
@@ -208,9 +214,9 @@ class BoxBlur(MultibandFilter):
             raise ValueError(msg)
         self.radius = radius
 
-    def filter(self, image):
+    def filter(self, image: _imaging.ImagingCore) -> _imaging.ImagingCore:
         xy = self.radius
-        if not isinstance(xy, (tuple, list)):
+        if isinstance(xy, (int, float)):
             xy = (xy, xy)
         if xy == (0, 0):
             return image.copy()
@@ -241,7 +247,7 @@ class UnsharpMask(MultibandFilter):
         self.percent = percent
         self.threshold = threshold
 
-    def filter(self, image):
+    def filter(self, image: _imaging.ImagingCore) -> _imaging.ImagingCore:
         return image.unsharp_mask(self.radius, self.percent, self.threshold)
 
 
@@ -387,8 +393,13 @@ class Color3DLUT(MultibandFilter):
     name = "Color 3D LUT"
 
     def __init__(
-        self, size, table, channels: int = 3, target_mode: str | None = None, **kwargs
-    ):
+        self,
+        size: int | tuple[int, int, int],
+        table: Sequence[float] | Sequence[Sequence[int]] | NumpyArray,
+        channels: int = 3,
+        target_mode: str | None = None,
+        **kwargs: bool,
+    ) -> None:
         if channels not in (3, 4):
             msg = "Only 3 or 4 output channels are supported"
             raise ValueError(msg)
@@ -410,15 +421,16 @@ class Color3DLUT(MultibandFilter):
                 pass
 
         if numpy and isinstance(table, numpy.ndarray):
+            numpy_table: NumpyArray = table
             if copy_table:
-                table = table.copy()
+                numpy_table = numpy_table.copy()
 
-            if table.shape in [
+            if numpy_table.shape in [
                 (items * channels,),
                 (items, channels),
                 (size[2], size[1], size[0], channels),
             ]:
-                table = table.reshape(items * channels)
+                table = numpy_table.reshape(items * channels)
             else:
                 wrong_size = True
 
@@ -428,7 +440,8 @@ class Color3DLUT(MultibandFilter):
 
             # Convert to a flat list
             if table and isinstance(table[0], (list, tuple)):
-                table, raw_table = [], table
+                raw_table = cast(Sequence[Sequence[int]], table)
+                flat_table: list[int] = []
                 for pixel in raw_table:
                     if len(pixel) != channels:
                         msg = (
@@ -436,7 +449,8 @@ class Color3DLUT(MultibandFilter):
                             f"have a length of {channels}."
                         )
                         raise ValueError(msg)
-                    table.extend(pixel)
+                    flat_table.extend(pixel)
+                table = flat_table
 
         if wrong_size or len(table) != items * channels:
             msg = (
@@ -449,7 +463,7 @@ class Color3DLUT(MultibandFilter):
         self.table = table
 
     @staticmethod
-    def _check_size(size: Any) -> list[int]:
+    def _check_size(size: Any) -> tuple[int, int, int]:
         try:
             _, _, _ = size
         except ValueError as e:
@@ -457,7 +471,7 @@ class Color3DLUT(MultibandFilter):
             raise ValueError(msg) from e
         except TypeError:
             size = (size, size, size)
-        size = [int(x) for x in size]
+        size = tuple(int(x) for x in size)
         for size_1d in size:
             if not 2 <= size_1d <= 65:
                 msg = "Size should be in [2, 65] range."
@@ -465,7 +479,13 @@ class Color3DLUT(MultibandFilter):
         return size
 
     @classmethod
-    def generate(cls, size, callback, channels=3, target_mode=None):
+    def generate(
+        cls,
+        size: int | tuple[int, int, int],
+        callback: Callable[[float, float, float], tuple[float, ...]],
+        channels: int = 3,
+        target_mode: str | None = None,
+    ) -> Color3DLUT:
         """Generates new LUT using provided callback.
 
         :param size: Size of the table. Passed to the constructor.
@@ -482,7 +502,7 @@ class Color3DLUT(MultibandFilter):
             msg = "Only 3 or 4 output channels are supported"
             raise ValueError(msg)
 
-        table = [0] * (size_1d * size_2d * size_3d * channels)
+        table: list[float] = [0] * (size_1d * size_2d * size_3d * channels)
         idx_out = 0
         for b in range(size_3d):
             for g in range(size_2d):
@@ -500,7 +520,13 @@ class Color3DLUT(MultibandFilter):
             _copy_table=False,
         )
 
-    def transform(self, callback, with_normals=False, channels=None, target_mode=None):
+    def transform(
+        self,
+        callback: Callable[..., tuple[float, ...]],
+        with_normals: bool = False,
+        channels: int | None = None,
+        target_mode: str | None = None,
+    ) -> Color3DLUT:
         """Transforms the table values using provided callback and returns
         a new LUT with altered values.
 
@@ -564,7 +590,7 @@ class Color3DLUT(MultibandFilter):
             r.append(f"target_mode={self.mode}")
         return "<{}>".format(" ".join(r))
 
-    def filter(self, image):
+    def filter(self, image: _imaging.ImagingCore) -> _imaging.ImagingCore:
         from . import Image
 
         return image.color_lut_3d(

src/PIL/_typing.py

@@ -2,7 +2,14 @@ from __future__ import annotations
 
 import os
 import sys
-from typing import Protocol, Sequence, TypeVar, Union
+from typing import Any, Protocol, Sequence, TypeVar, Union
+
+try:
+    import numpy.typing as npt
+
+    NumpyArray = npt.NDArray[Any]
+except ImportError:
+    pass
 
 if sys.version_info >= (3, 10):
     from typing import TypeGuard
@@ -10,7 +17,6 @@ else:
     try:
         from typing_extensions import TypeGuard
     except ImportError:
-        from typing import Any
 
         class TypeGuard:  # type: ignore[no-redef]
             def __class_getitem__(cls, item: Any) -> type[bool]: