Deprecate putpixel value lists

Tests/test_image_access.py

@@ -119,6 +119,11 @@ def test_numpy(self) -> None:
         assert numpy is not None
         assert px[numpy.int32(1), numpy.int32(2)] == (18, 20, 59)
 
+    def test_deprecation(self) -> None:
+        im = Image.new("PA", (1, 1))
+        with pytest.warns(DeprecationWarning, match="'value' lists"):
+            im.putpixel((0, 0), [0, 0, 0])  # type: ignore[arg-type]
+
 
 class TestImageGetPixel:
     @staticmethod

docs/deprecations.rst

@@ -31,6 +31,14 @@ The IM image format has been deprecated and removal is planned in Pillow 15.0.0
 (2028-10-15). If you are using this format and would like to continue doing so,
 open an issue about what other software uses it.
 
+Image.putpixel 'value' lists
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. deprecated:: 13.0.0
+
+Passing lists to the ``value`` parameter of :py:meth:`~PIL.Image.Image.putpixel` have
+been deprecated. Use tuples instead.
+
 ImageQt align8to32()
 ^^^^^^^^^^^^^^^^^^^^
 

docs/releasenotes/13.0.0.rst

@@ -81,6 +81,12 @@ The IM image format has been deprecated and removal is planned in Pillow 15.0.0
 (2028-10-15). If you are using this format and would like to continue doing so,
 open an issue about what other software uses it.
 
+Image.putpixel 'value' lists
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Passing lists to the ``value`` parameter of :py:meth:`~PIL.Image.Image.putpixel` have
+been deprecated. Use tuples instead.
+
 JpegImageFile.load_djpeg
 ^^^^^^^^^^^^^^^^^^^^^^^^
 

src/PIL/Image.py

@@ -2183,7 +2183,7 @@ def putpalette(
     def putpixel(
         self,
         xy: tuple[int, int] | list[int],
-        value: float | tuple[int, ...] | list[int],
+        value: float | tuple[int, ...],
     ) -> None:
         """
         Modifies the pixel at the given position. The color is given as
@@ -2213,6 +2213,9 @@ def putpixel(
             and isinstance(value, (list, tuple))
             and len(value) in [3, 4]
         ):
+            if isinstance(value, list):  # type: ignore[unreachable]
+                deprecate("'value' lists", 14, "tuples", plural=True)  # type: ignore[unreachable]
+
             # RGB or RGBA value for a P or PA image
             if self.mode == "PA":
                 alpha = value[3] if len(value) == 4 else 255