diff --git a/Tests/test_decompression_bomb.py b/Tests/test_decompression_bomb.py
index 9c21efa45f7..c140156f9ea 100644
--- a/Tests/test_decompression_bomb.py
+++ b/Tests/test_decompression_bomb.py
@@ -12,7 +12,7 @@
 
 
 class TestDecompressionBomb:
-    def teardown_method(self, method) -> None:
+    def teardown_method(self) -> None:
         Image.MAX_IMAGE_PIXELS = ORIGINAL_LIMIT
 
     def test_no_warning_small_file(self) -> None:
diff --git a/Tests/test_file_jpeg.py b/Tests/test_file_jpeg.py
index 18dc752d8bd..1459a87eb13 100644
--- a/Tests/test_file_jpeg.py
+++ b/Tests/test_file_jpeg.py
@@ -443,7 +443,9 @@ def test_smooth(self) -> None:
         assert_image(im1, im2.mode, im2.size)
 
     def test_subsampling(self) -> None:
-        def getsampling(im: JpegImagePlugin.JpegImageFile):
+        def getsampling(
+            im: JpegImagePlugin.JpegImageFile,
+        ) -> tuple[int, int, int, int, int, int]:
             layer = im.layer
             return layer[0][1:3] + layer[1][1:3] + layer[2][1:3]
 
@@ -699,7 +701,7 @@ def test_load_djpeg(self) -> None:
     def test_save_cjpeg(self, tmp_path: Path) -> None:
         with Image.open(TEST_FILE) as img:
             tempfile = str(tmp_path / "temp.jpg")
-            JpegImagePlugin._save_cjpeg(img, 0, tempfile)
+            JpegImagePlugin._save_cjpeg(img, BytesIO(), tempfile)
             # Default save quality is 75%, so a tiny bit of difference is alright
             assert_image_similar_tofile(img, tempfile, 17)
 
@@ -917,24 +919,25 @@ def test_icc_after_SOF(self) -> None:
         with Image.open("Tests/images/icc-after-SOF.jpg") as im:
             assert im.info["icc_profile"] == b"profile"
 
-    def test_jpeg_magic_number(self) -> None:
+    def test_jpeg_magic_number(self, monkeypatch: pytest.MonkeyPatch) -> None:
         size = 4097
         buffer = BytesIO(b"\xFF" * size)  # Many xFF bytes
-        buffer.max_pos = 0
+        max_pos = 0
         orig_read = buffer.read
 
-        def read(n=-1):
+        def read(n: int | None = -1) -> bytes:
+            nonlocal max_pos
             res = orig_read(n)
-            buffer.max_pos = max(buffer.max_pos, buffer.tell())
+            max_pos = max(max_pos, buffer.tell())
             return res
 
-        buffer.read = read
+        monkeypatch.setattr(buffer, "read", read)
         with pytest.raises(UnidentifiedImageError):
             with Image.open(buffer):
                 pass
 
         # Assert the entire file has not been read
-        assert 0 < buffer.max_pos < size
+        assert 0 < max_pos < size
 
     def test_getxmp(self) -> None:
         with Image.open("Tests/images/xmp_test.jpg") as im:
diff --git a/Tests/test_file_jpeg2k.py b/Tests/test_file_jpeg2k.py
index 5a208739f70..ed7ea4fcfbc 100644
--- a/Tests/test_file_jpeg2k.py
+++ b/Tests/test_file_jpeg2k.py
@@ -460,7 +460,7 @@ def test_plt_marker() -> None:
         out.seek(length - 2, os.SEEK_CUR)
 
 
-def test_9bit():
+def test_9bit() -> None:
     with Image.open("Tests/images/9bit.j2k") as im:
         assert im.mode == "I;16"
         assert im.size == (128, 128)
diff --git a/Tests/test_file_tiff.py b/Tests/test_file_tiff.py
index 8821fb46a84..06591a29a37 100644
--- a/Tests/test_file_tiff.py
+++ b/Tests/test_file_tiff.py
@@ -113,7 +113,7 @@ def test_bigtiff(self, tmp_path: Path) -> None:
             outfile = str(tmp_path / "temp.tif")
             im.save(outfile, save_all=True, append_images=[im], tiffinfo=im.tag_v2)
 
-    def test_seek_too_large(self):
+    def test_seek_too_large(self) -> None:
         with pytest.raises(ValueError, match="Unable to seek to frame"):
             Image.open("Tests/images/seek_too_large.tif")
 
diff --git a/Tests/test_image.py b/Tests/test_image.py
index d6a739c79df..0d7d034806c 100644
--- a/Tests/test_image.py
+++ b/Tests/test_image.py
@@ -152,7 +152,7 @@ def test_bad_mode(self) -> None:
 
     def test_stringio(self) -> None:
         with pytest.raises(ValueError):
-            with Image.open(io.StringIO()):
+            with Image.open(io.StringIO()):  # type: ignore[arg-type]
                 pass
 
     def test_pathlib(self, tmp_path: Path) -> None:
diff --git a/Tests/test_image_mode.py b/Tests/test_image_mode.py
index 8e94aafc598..20d3a160e9c 100644
--- a/Tests/test_image_mode.py
+++ b/Tests/test_image_mode.py
@@ -68,7 +68,11 @@ def test_sanity() -> None:
     ),
 )
 def test_properties(
-    mode, expected_base, expected_type, expected_bands, expected_band_names
+    mode: str,
+    expected_base: str,
+    expected_type: str,
+    expected_bands: int,
+    expected_band_names: tuple[str, ...],
 ) -> None:
     assert Image.getmodebase(mode) == expected_base
     assert Image.getmodetype(mode) == expected_type
diff --git a/Tests/test_image_putdata.py b/Tests/test_image_putdata.py
index dad26ef144c..5e57e4c4c8f 100644
--- a/Tests/test_image_putdata.py
+++ b/Tests/test_image_putdata.py
@@ -113,13 +113,13 @@ def test_array_F() -> None:
 def test_not_flattened() -> None:
     im = Image.new("L", (1, 1))
     with pytest.raises(TypeError):
-        im.putdata([[0]])
+        im.putdata([[0]])  # type: ignore[list-item]
     with pytest.raises(TypeError):
-        im.putdata([[0]], 2)
+        im.putdata([[0]], 2)  # type: ignore[list-item]
 
     with pytest.raises(TypeError):
         im = Image.new("I", (1, 1))
-        im.putdata([[0]])
+        im.putdata([[0]])  # type: ignore[list-item]
     with pytest.raises(TypeError):
         im = Image.new("F", (1, 1))
-        im.putdata([[0]])
+        im.putdata([[0]])  # type: ignore[list-item]
diff --git a/Tests/test_image_quantize.py b/Tests/test_image_quantize.py
index 2daaf5c3cbb..2d461d985dd 100644
--- a/Tests/test_image_quantize.py
+++ b/Tests/test_image_quantize.py
@@ -98,7 +98,7 @@ def test_quantize_dither_diff() -> None:
 @pytest.mark.parametrize(
     "method", (Image.Quantize.MEDIANCUT, Image.Quantize.MAXCOVERAGE)
 )
-def test_quantize_kmeans(method) -> None:
+def test_quantize_kmeans(method: Image.Quantize) -> None:
     im = hopper()
     no_kmeans = im.quantize(kmeans=0, method=method)
     kmeans = im.quantize(kmeans=1, method=method)
diff --git a/Tests/test_image_reduce.py b/Tests/test_image_reduce.py
index f6609a1a054..6771b46b051 100644
--- a/Tests/test_image_reduce.py
+++ b/Tests/test_image_reduce.py
@@ -56,10 +56,12 @@ def test_args_factor(size: int | tuple[int, int], expected: tuple[int, int]) ->
 @pytest.mark.parametrize(
     "size, expected_error", ((0, ValueError), (2.0, TypeError), ((0, 10), ValueError))
 )
-def test_args_factor_error(size: float | tuple[int, int], expected_error) -> None:
+def test_args_factor_error(
+    size: float | tuple[int, int], expected_error: type[Exception]
+) -> None:
     im = Image.new("L", (10, 10))
     with pytest.raises(expected_error):
-        im.reduce(size)
+        im.reduce(size)  # type: ignore[arg-type]
 
 
 @pytest.mark.parametrize(
@@ -86,10 +88,12 @@ def test_args_box(size: tuple[int, int, int, int], expected: tuple[int, int]) ->
         ((5, 0, 5, 10), ValueError),
     ),
 )
-def test_args_box_error(size: str | tuple[int, int, int, int], expected_error) -> None:
+def test_args_box_error(
+    size: str | tuple[int, int, int, int], expected_error: type[Exception]
+) -> None:
     im = Image.new("L", (10, 10))
     with pytest.raises(expected_error):
-        im.reduce(2, size).size
+        im.reduce(2, size).size  # type: ignore[arg-type]
 
 
 @pytest.mark.parametrize("mode", ("P", "1", "I;16"))
diff --git a/Tests/test_image_thumbnail.py b/Tests/test_image_thumbnail.py
index 1593eaaf7fa..bdbf09c407e 100644
--- a/Tests/test_image_thumbnail.py
+++ b/Tests/test_image_thumbnail.py
@@ -16,7 +16,7 @@
 
 def test_sanity() -> None:
     im = hopper()
-    assert im.thumbnail((100, 100)) is None
+    im.thumbnail((100, 100))
 
     assert im.size == (100, 100)
 
diff --git a/Tests/test_imagedraw.py b/Tests/test_imagedraw.py
index 61d7b5c6a18..d9593c60f60 100644
--- a/Tests/test_imagedraw.py
+++ b/Tests/test_imagedraw.py
@@ -1562,7 +1562,11 @@ def test_compute_regular_polygon_vertices(
     ],
 )
 def test_compute_regular_polygon_vertices_input_error_handling(
-    n_sides, bounding_circle, rotation, expected_error, error_message
+    n_sides: int,
+    bounding_circle: int | tuple[int | tuple[int] | str, ...],
+    rotation: int | str,
+    expected_error: type[Exception],
+    error_message: str,
 ) -> None:
     with pytest.raises(expected_error) as e:
         ImageDraw._compute_regular_polygon_vertices(bounding_circle, n_sides, rotation)
diff --git a/Tests/test_imagefont.py b/Tests/test_imagefont.py
index 4398f8a3055..73cad513e62 100644
--- a/Tests/test_imagefont.py
+++ b/Tests/test_imagefont.py
@@ -224,7 +224,7 @@ def test_render_multiline(font: ImageFont.FreeTypeFont) -> None:
     draw = ImageDraw.Draw(im)
     line_spacing = font.getbbox("A")[3] + 4
     lines = TEST_TEXT.split("\n")
-    y = 0
+    y: float = 0
     for line in lines:
         draw.text((0, y), line, font=font)
         y += line_spacing
diff --git a/Tests/test_imageops.py b/Tests/test_imageops.py
index d6bdaf45073..27a6090c5fa 100644
--- a/Tests/test_imageops.py
+++ b/Tests/test_imageops.py
@@ -454,7 +454,7 @@ def test_autocontrast_cutoff() -> None:
     # Test the cutoff argument of autocontrast
     with Image.open("Tests/images/bw_gradient.png") as img:
 
-        def autocontrast(cutoff: int | tuple[int, int]):
+        def autocontrast(cutoff: int | tuple[int, int]) -> list[int]:
             return ImageOps.autocontrast(img, cutoff).histogram()
 
         assert autocontrast(10) == autocontrast((10, 10))
diff --git a/Tests/test_imagewin_pointers.py b/Tests/test_imagewin_pointers.py
index f59ee7284b8..e6c312a0c46 100644
--- a/Tests/test_imagewin_pointers.py
+++ b/Tests/test_imagewin_pointers.py
@@ -70,7 +70,7 @@ class BITMAPINFOHEADER(ctypes.Structure):
     ]
     CreateDIBSection.restype = ctypes.wintypes.HBITMAP
 
-    def serialize_dib(bi, pixels) -> bytearray:
+    def serialize_dib(bi: BITMAPINFOHEADER, pixels: ctypes.c_void_p) -> bytearray:
         bf = BITMAPFILEHEADER()
         bf.bfType = 0x4D42
         bf.bfOffBits = ctypes.sizeof(bf) + bi.biSize
diff --git a/Tests/test_main.py b/Tests/test_main.py
index e9e12b24a79..2582dbee3db 100644
--- a/Tests/test_main.py
+++ b/Tests/test_main.py
@@ -11,7 +11,7 @@
     "args, report",
     ((["PIL"], False), (["PIL", "--report"], True), (["PIL.report"], True)),
 )
-def test_main(args, report) -> None:
+def test_main(args: list[str], report: bool) -> None:
     args = [sys.executable, "-m"] + args
     out = subprocess.check_output(args).decode("utf-8")
     lines = out.splitlines()
diff --git a/Tests/test_numpy.py b/Tests/test_numpy.py
index 9f4e6534e8a..36cdb368267 100644
--- a/Tests/test_numpy.py
+++ b/Tests/test_numpy.py
@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import warnings
+from typing import TYPE_CHECKING, Any
 
 import pytest
 
@@ -8,13 +9,19 @@
 
 from .helper import assert_deep_equal, assert_image, hopper, skip_unless_feature
 
-numpy = pytest.importorskip("numpy", reason="NumPy not installed")
+if TYPE_CHECKING:
+    import numpy
+    import numpy.typing
+else:
+    numpy = pytest.importorskip("numpy", reason="NumPy not installed")
 
 TEST_IMAGE_SIZE = (10, 10)
 
 
 def test_numpy_to_image() -> None:
-    def to_image(dtype, bands: int = 1, boolean: int = 0) -> Image.Image:
+    def to_image(
+        dtype: numpy.typing.DTypeLike, bands: int = 1, boolean: int = 0
+    ) -> Image.Image:
         if bands == 1:
             if boolean:
                 data = [0, 255] * 50
@@ -99,14 +106,16 @@ def test_1d_array() -> None:
     assert_image(Image.fromarray(a), "L", (1, 5))
 
 
-def _test_img_equals_nparray(img: Image.Image, np) -> None:
-    assert len(np.shape) >= 2
-    np_size = np.shape[1], np.shape[0]
+def _test_img_equals_nparray(
+    img: Image.Image, np_img: numpy.typing.NDArray[Any]
+) -> None:
+    assert len(np_img.shape) >= 2
+    np_size = np_img.shape[1], np_img.shape[0]
     assert img.size == np_size
     px = img.load()
     for x in range(0, img.size[0], int(img.size[0] / 10)):
         for y in range(0, img.size[1], int(img.size[1] / 10)):
-            assert_deep_equal(px[x, y], np[y, x])
+            assert_deep_equal(px[x, y], np_img[y, x])
 
 
 def test_16bit() -> None:
@@ -157,7 +166,7 @@ def test_save_tiff_uint16() -> None:
         ("HSV", numpy.uint8),
     ),
 )
-def test_to_array(mode: str, dtype) -> None:
+def test_to_array(mode: str, dtype: numpy.typing.DTypeLike) -> None:
     img = hopper(mode)
 
     # Resize to non-square
@@ -207,7 +216,7 @@ def test_putdata() -> None:
         numpy.float64,
     ),
 )
-def test_roundtrip_eye(dtype) -> None:
+def test_roundtrip_eye(dtype: numpy.typing.DTypeLike) -> None:
     arr = numpy.eye(10, dtype=dtype)
     numpy.testing.assert_array_equal(arr, numpy.array(Image.fromarray(arr)))
 
diff --git a/Tests/test_shell_injection.py b/Tests/test_shell_injection.py
index 2a072fd44c5..dd4fc46c374 100644
--- a/Tests/test_shell_injection.py
+++ b/Tests/test_shell_injection.py
@@ -1,8 +1,9 @@
 from __future__ import annotations
 
 import shutil
+from io import BytesIO
 from pathlib import Path
-from typing import Callable
+from typing import IO, Callable
 
 import pytest
 
@@ -22,11 +23,11 @@ def assert_save_filename_check(
         self,
         tmp_path: Path,
         src_img: Image.Image,
-        save_func: Callable[[Image.Image, int, str], None],
+        save_func: Callable[[Image.Image, IO[bytes], str | bytes], None],
     ) -> None:
         for filename in test_filenames:
             dest_file = str(tmp_path / filename)
-            save_func(src_img, 0, dest_file)
+            save_func(src_img, BytesIO(), dest_file)
             # If file can't be opened, shell injection probably occurred
             with Image.open(dest_file) as im:
                 im.load()
diff --git a/src/PIL/BdfFontFile.py b/src/PIL/BdfFontFile.py
index e3eda4fe98c..bc1416c74c6 100644
--- a/src/PIL/BdfFontFile.py
+++ b/src/PIL/BdfFontFile.py
@@ -103,7 +103,7 @@ def bdf_char(
 class BdfFontFile(FontFile.FontFile):
     """Font file plugin for the X11 BDF format."""
 
-    def __init__(self, fp: BinaryIO):
+    def __init__(self, fp: BinaryIO) -> None:
         super().__init__()
 
         s = fp.readline()
diff --git a/src/PIL/ImageDraw.py b/src/PIL/ImageDraw.py
index e74fab9fb3d..41a3eb0cb46 100644
--- a/src/PIL/ImageDraw.py
+++ b/src/PIL/ImageDraw.py
@@ -34,12 +34,16 @@
 import math
 import numbers
 import struct
+from types import ModuleType
 from typing import TYPE_CHECKING, AnyStr, Sequence, cast
 
 from . import Image, ImageColor
 from ._deprecate import deprecate
 from ._typing import Coords
 
+if TYPE_CHECKING:
+    from . import ImageDraw2, ImageFont
+
 """
 A simple 2D drawing interface for PIL images.
 <p>
@@ -93,9 +97,6 @@ def __init__(self, im: Image.Image, mode: str | None = None) -> None:
             self.fontmode = "L"  # aliasing is okay for other modes
         self.fill = False
 
-    if TYPE_CHECKING:
-        from . import ImageFont
-
     def getfont(
         self,
     ) -> ImageFont.ImageFont | ImageFont.FreeTypeFont | ImageFont.TransposedFont:
@@ -879,7 +880,7 @@ def multiline_textbbox(
         return bbox
 
 
-def Draw(im, mode: str | None = None) -> ImageDraw:
+def Draw(im: Image.Image, mode: str | None = None) -> ImageDraw:
     """
     A simple 2D drawing interface for PIL images.
 
@@ -891,7 +892,7 @@ def Draw(im, mode: str | None = None) -> ImageDraw:
        defaults to the mode of the image.
     """
     try:
-        return im.getdraw(mode)
+        return getattr(im, "getdraw")(mode)
     except AttributeError:
         return ImageDraw(im, mode)
 
@@ -903,7 +904,9 @@ def Draw(im, mode: str | None = None) -> ImageDraw:
     Outline = None
 
 
-def getdraw(im=None, hints=None):
+def getdraw(
+    im: Image.Image | None = None, hints: list[str] | None = None
+) -> tuple[ImageDraw2.Draw | None, ModuleType]:
     """
     :param im: The image to draw in.
     :param hints: An optional list of hints. Deprecated.
@@ -913,9 +916,8 @@ def getdraw(im=None, hints=None):
         deprecate("'hints' parameter", 12)
     from . import ImageDraw2
 
-    if im:
-        im = ImageDraw2.Draw(im)
-    return im, ImageDraw2
+    draw = ImageDraw2.Draw(im) if im is not None else None
+    return draw, ImageDraw2
 
 
 def floodfill(
diff --git a/src/PIL/ImagePalette.py b/src/PIL/ImagePalette.py
index 1ff05a3eff1..6473c4577b0 100644
--- a/src/PIL/ImagePalette.py
+++ b/src/PIL/ImagePalette.py
@@ -54,7 +54,7 @@ def palette(self, palette):
         self._palette = palette
 
     @property
-    def colors(self):
+    def colors(self) -> dict[tuple[int, int, int] | tuple[int, int, int, int], int]:
         if self._colors is None:
             mode_len = len(self.mode)
             self._colors = {}
@@ -66,7 +66,9 @@ def colors(self):
         return self._colors
 
     @colors.setter
-    def colors(self, colors):
+    def colors(
+        self, colors: dict[tuple[int, int, int] | tuple[int, int, int, int], int]
+    ) -> None:
         self._colors = colors
 
     def copy(self) -> ImagePalette:
@@ -107,11 +109,13 @@ def tobytes(self) -> bytes:
     # Declare tostring as an alias for tobytes
     tostring = tobytes
 
-    def _new_color_index(self, image=None, e=None):
+    def _new_color_index(
+        self, image: Image.Image | None = None, e: Exception | None = None
+    ) -> int:
         if not isinstance(self.palette, bytearray):
             self._palette = bytearray(self.palette)
         index = len(self.palette) // 3
-        special_colors = ()
+        special_colors: tuple[int | tuple[int, ...] | None, ...] = ()
         if image:
             special_colors = (
                 image.info.get("background"),
diff --git a/src/PIL/MicImagePlugin.py b/src/PIL/MicImagePlugin.py
index ed2ea2849d0..07239887f9f 100644
--- a/src/PIL/MicImagePlugin.py
+++ b/src/PIL/MicImagePlugin.py
@@ -63,7 +63,7 @@ def _open(self) -> None:
             msg = "not an MIC file; no image entries"
             raise SyntaxError(msg)
 
-        self.frame = None
+        self.frame = -1
         self._n_frames = len(self.images)
         self.is_animated = self._n_frames > 1
 
@@ -85,7 +85,7 @@ def seek(self, frame):
 
         self.frame = frame
 
-    def tell(self):
+    def tell(self) -> int:
         return self.frame
 
     def close(self) -> None:
diff --git a/src/PIL/PngImagePlugin.py b/src/PIL/PngImagePlugin.py
index ba95980653a..927d6c0cfbd 100644
--- a/src/PIL/PngImagePlugin.py
+++ b/src/PIL/PngImagePlugin.py
@@ -39,7 +39,7 @@
 import warnings
 import zlib
 from enum import IntEnum
-from typing import IO, Any
+from typing import IO, TYPE_CHECKING, Any, NoReturn
 
 from . import Image, ImageChops, ImageFile, ImagePalette, ImageSequence
 from ._binary import i16be as i16
@@ -48,6 +48,9 @@
 from ._binary import o16be as o16
 from ._binary import o32be as o32
 
+if TYPE_CHECKING:
+    from . import _imaging
+
 logger = logging.getLogger(__name__)
 
 is_cid = re.compile(rb"\w\w\w\w").match
@@ -249,6 +252,9 @@ class iTXt(str):
 
     """
 
+    lang: str | bytes | None
+    tkey: str | bytes | None
+
     @staticmethod
     def __new__(cls, text, lang=None, tkey=None):
         """
@@ -270,10 +276,10 @@ class PngInfo:
 
     """
 
-    def __init__(self):
-        self.chunks = []
+    def __init__(self) -> None:
+        self.chunks: list[tuple[bytes, bytes, bool]] = []
 
-    def add(self, cid, data, after_idat=False):
+    def add(self, cid: bytes, data: bytes, after_idat: bool = False) -> None:
         """Appends an arbitrary chunk. Use with caution.
 
         :param cid: a byte string, 4 bytes long.
@@ -283,12 +289,16 @@ def add(self, cid, data, after_idat=False):
 
         """
 
-        chunk = [cid, data]
-        if after_idat:
-            chunk.append(True)
-        self.chunks.append(tuple(chunk))
+        self.chunks.append((cid, data, after_idat))
 
-    def add_itxt(self, key, value, lang="", tkey="", zip=False):
+    def add_itxt(
+        self,
+        key: str | bytes,
+        value: str | bytes,
+        lang: str | bytes = "",
+        tkey: str | bytes = "",
+        zip: bool = False,
+    ) -> None:
         """Appends an iTXt chunk.
 
         :param key: latin-1 encodable text key name
@@ -316,7 +326,9 @@ def add_itxt(self, key, value, lang="", tkey="", zip=False):
         else:
             self.add(b"iTXt", key + b"\0\0\0" + lang + b"\0" + tkey + b"\0" + value)
 
-    def add_text(self, key, value, zip=False):
+    def add_text(
+        self, key: str | bytes, value: str | bytes | iTXt, zip: bool = False
+    ) -> None:
         """Appends a text chunk.
 
         :param key: latin-1 encodable text key name
@@ -326,7 +338,13 @@ def add_text(self, key, value, zip=False):
 
         """
         if isinstance(value, iTXt):
-            return self.add_itxt(key, value, value.lang, value.tkey, zip=zip)
+            return self.add_itxt(
+                key,
+                value,
+                value.lang if value.lang is not None else b"",
+                value.tkey if value.tkey is not None else b"",
+                zip=zip,
+            )
 
         # The tEXt chunk stores latin-1 text
         if not isinstance(value, bytes):
@@ -434,7 +452,7 @@ def chunk_IHDR(self, pos: int, length: int) -> bytes:
             raise SyntaxError(msg)
         return s
 
-    def chunk_IDAT(self, pos, length):
+    def chunk_IDAT(self, pos: int, length: int) -> NoReturn:
         # image data
         if "bbox" in self.im_info:
             tile = [("zip", self.im_info["bbox"], pos, self.im_rawmode)]
@@ -447,7 +465,7 @@ def chunk_IDAT(self, pos, length):
         msg = "image data found"
         raise EOFError(msg)
 
-    def chunk_IEND(self, pos, length):
+    def chunk_IEND(self, pos: int, length: int) -> NoReturn:
         msg = "end of PNG image"
         raise EOFError(msg)
 
@@ -821,7 +839,10 @@ def seek(self, frame: int) -> None:
                 msg = "no more images in APNG file"
                 raise EOFError(msg) from e
 
-    def _seek(self, frame, rewind=False):
+    def _seek(self, frame: int, rewind: bool = False) -> None:
+        assert self.png is not None
+
+        self.dispose: _imaging.ImagingCore | None
         if frame == 0:
             if rewind:
                 self._fp.seek(self.__rewind)
@@ -906,14 +927,14 @@ def _seek(self, frame, rewind=False):
         if self._prev_im is None and self.dispose_op == Disposal.OP_PREVIOUS:
             self.dispose_op = Disposal.OP_BACKGROUND
 
+        self.dispose = None
         if self.dispose_op == Disposal.OP_PREVIOUS:
-            self.dispose = self._prev_im.copy()
-            self.dispose = self._crop(self.dispose, self.dispose_extent)
+            if self._prev_im:
+                self.dispose = self._prev_im.copy()
+                self.dispose = self._crop(self.dispose, self.dispose_extent)
         elif self.dispose_op == Disposal.OP_BACKGROUND:
             self.dispose = Image.core.fill(self.mode, self.size)
             self.dispose = self._crop(self.dispose, self.dispose_extent)
-        else:
-            self.dispose = None
 
     def tell(self) -> int:
         return self.__frame
@@ -1026,7 +1047,7 @@ def _getexif(self) -> dict[str, Any] | None:
             return None
         return self.getexif()._get_merged_dict()
 
-    def getexif(self):
+    def getexif(self) -> Image.Exif:
         if "exif" not in self.info:
             self.load()
 
@@ -1346,7 +1367,7 @@ def _save(im, fp, filename, chunk=putchunk, save_all=False):
                 chunk(fp, cid, data)
             elif cid[1:2].islower():
                 # Private chunk
-                after_idat = info_chunk[2:3]
+                after_idat = len(info_chunk) == 3 and info_chunk[2]
                 if not after_idat:
                     chunk(fp, cid, data)
 
@@ -1425,7 +1446,7 @@ def _save(im, fp, filename, chunk=putchunk, save_all=False):
             cid, data = info_chunk[:2]
             if cid[1:2].islower():
                 # Private chunk
-                after_idat = info_chunk[2:3]
+                after_idat = len(info_chunk) == 3 and info_chunk[2]
                 if after_idat:
                     chunk(fp, cid, data)
 
diff --git a/src/PIL/TiffImagePlugin.py b/src/PIL/TiffImagePlugin.py
index 702d8f33b5b..833e12d2b37 100644
--- a/src/PIL/TiffImagePlugin.py
+++ b/src/PIL/TiffImagePlugin.py
@@ -50,7 +50,7 @@
 from collections.abc import MutableMapping
 from fractions import Fraction
 from numbers import Number, Rational
-from typing import IO, TYPE_CHECKING, Any, Callable
+from typing import IO, TYPE_CHECKING, Any, Callable, NoReturn
 
 from . import ExifTags, Image, ImageFile, ImageOps, ImagePalette, TiffTags
 from ._binary import i16be as i16
@@ -384,7 +384,7 @@ def limit_rational(self, max_denominator):
     def __repr__(self) -> str:
         return str(float(self._val))
 
-    def __hash__(self):
+    def __hash__(self) -> int:
         return self._val.__hash__()
 
     def __eq__(self, other: object) -> bool:
@@ -551,7 +551,12 @@ class ImageFileDirectory_v2(_IFDv2Base):
     _load_dispatch: dict[int, Callable[[ImageFileDirectory_v2, bytes, bool], Any]] = {}
     _write_dispatch: dict[int, Callable[..., Any]] = {}
 
-    def __init__(self, ifh=b"II\052\0\0\0\0\0", prefix=None, group=None):
+    def __init__(
+        self,
+        ifh: bytes = b"II\052\0\0\0\0\0",
+        prefix: bytes | None = None,
+        group: int | None = None,
+    ) -> None:
         """Initialize an ImageFileDirectory.
 
         To construct an ImageFileDirectory from a real file, pass the 8-byte
@@ -575,7 +580,7 @@ def __init__(self, ifh=b"II\052\0\0\0\0\0", prefix=None, group=None):
             raise SyntaxError(msg)
         self._bigtiff = ifh[2] == 43
         self.group = group
-        self.tagtype = {}
+        self.tagtype: dict[int, int] = {}
         """ Dictionary of tag types """
         self.reset()
         (self.next,) = (
@@ -587,18 +592,18 @@ def __init__(self, ifh=b"II\052\0\0\0\0\0", prefix=None, group=None):
     offset = property(lambda self: self._offset)
 
     @property
-    def legacy_api(self):
+    def legacy_api(self) -> bool:
         return self._legacy_api
 
     @legacy_api.setter
-    def legacy_api(self, value):
+    def legacy_api(self, value: bool) -> NoReturn:
         msg = "Not allowing setting of legacy api"
         raise Exception(msg)
 
-    def reset(self):
-        self._tags_v1 = {}  # will remain empty if legacy_api is false
-        self._tags_v2 = {}  # main tag storage
-        self._tagdata = {}
+    def reset(self) -> None:
+        self._tags_v1: dict[int, Any] = {}  # will remain empty if legacy_api is false
+        self._tags_v2: dict[int, Any] = {}  # main tag storage
+        self._tagdata: dict[int, bytes] = {}
         self.tagtype = {}  # added 2008-06-05 by Florian Hoech
         self._next = None
         self._offset = None
@@ -2039,7 +2044,7 @@ def skipIFDs(self) -> None:
             num_tags = self.readShort()
             self.f.seek(num_tags * 12, os.SEEK_CUR)
 
-    def write(self, data):
+    def write(self, data: bytes) -> int | None:
         return self.f.write(data)
 
     def readShort(self) -> int:
@@ -2122,7 +2127,9 @@ def fixIFD(self) -> None:
                 # skip the locally stored value that is not an offset
                 self.f.seek(4, os.SEEK_CUR)
 
-    def fixOffsets(self, count, isShort=False, isLong=False):
+    def fixOffsets(
+        self, count: int, isShort: bool = False, isLong: bool = False
+    ) -> None:
         if not isShort and not isLong:
             msg = "offset is neither short nor long"
             raise RuntimeError(msg)
diff --git a/src/PIL/_imaging.pyi b/src/PIL/_imaging.pyi
index 3467eeb4549..dda06b5a1af 100644
--- a/src/PIL/_imaging.pyi
+++ b/src/PIL/_imaging.pyi
@@ -18,5 +18,5 @@ class ImagingDecoder:
 class ImagingEncoder:
     def __getattr__(self, name: str) -> Any: ...
 
-def font(image, glyphdata: bytes) -> ImagingFont: ...
+def font(image: ImagingCore, glyphdata: bytes) -> ImagingFont: ...
 def __getattr__(name: str) -> Any: ...
diff --git a/src/PIL/features.py b/src/PIL/features.py
index 16c749f148b..13908c4eb78 100644
--- a/src/PIL/features.py
+++ b/src/PIL/features.py
@@ -4,6 +4,7 @@
 import os
 import sys
 import warnings
+from typing import IO
 
 import PIL
 
@@ -223,7 +224,7 @@ def get_supported() -> list[str]:
     return ret
 
 
-def pilinfo(out=None, supported_formats=True):
+def pilinfo(out: IO[str] | None = None, supported_formats: bool = True) -> None:
     """
     Prints information about this installation of Pillow.
     This function can be called with ``python3 -m PIL``.
@@ -244,9 +245,9 @@ def pilinfo(out=None, supported_formats=True):
 
     print("-" * 68, file=out)
     print(f"Pillow {PIL.__version__}", file=out)
-    py_version = sys.version.splitlines()
-    print(f"Python {py_version[0].strip()}", file=out)
-    for py_version in py_version[1:]:
+    py_version_lines = sys.version.splitlines()
+    print(f"Python {py_version_lines[0].strip()}", file=out)
+    for py_version in py_version_lines[1:]:
         print(f"       {py_version.strip()}", file=out)
     print("-" * 68, file=out)
     print(f"Python executable is {sys.executable or 'unknown'}", file=out)
@@ -282,9 +283,12 @@ def pilinfo(out=None, supported_formats=True):
         ("xcb", "XCB (X protocol)"),
     ]:
         if check(name):
-            if name == "jpg" and check_feature("libjpeg_turbo"):
-                v = "libjpeg-turbo " + version_feature("libjpeg_turbo")
-            else:
+            v: str | None = None
+            if name == "jpg":
+                libjpeg_turbo_version = version_feature("libjpeg_turbo")
+                if libjpeg_turbo_version is not None:
+                    v = "libjpeg-turbo " + libjpeg_turbo_version
+            if v is None:
                 v = version(name)
             if v is not None:
                 version_static = name in ("pil", "jpg")