From e6af31e709eb61c553d13fb8648772379211f250 Mon Sep 17 00:00:00 2001
From: Andrew Murray <radarhere@users.noreply.github.com>
Date: Sat, 14 Jun 2025 16:09:11 +1000
Subject: [PATCH] Deprecate fromarray mode argument

---
 Tests/test_image_array.py    | 6 ++++--
 docs/deprecations.rst        | 8 ++++++++
 docs/releasenotes/11.3.0.rst | 7 ++++---
 src/PIL/Image.py             | 3 ++-
 4 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/Tests/test_image_array.py b/Tests/test_image_array.py
index eb2309e0f..2c71dceb8 100644
--- a/Tests/test_image_array.py
+++ b/Tests/test_image_array.py
@@ -101,7 +101,8 @@ def test_fromarray_strides_without_tobytes() -> None:
 
     with pytest.raises(ValueError):
         wrapped = Wrapper({"shape": (1, 1), "strides": (1, 1)})
-        Image.fromarray(wrapped, "L")
+        with pytest.warns(DeprecationWarning):
+            Image.fromarray(wrapped, "L")
 
 
 def test_fromarray_palette() -> None:
@@ -110,7 +111,8 @@ def test_fromarray_palette() -> None:
     a = numpy.array(i)
 
     # Act
-    out = Image.fromarray(a, "P")
+    with pytest.warns(DeprecationWarning):
+        out = Image.fromarray(a, "P")
 
     # Assert that the Python and C palettes match
     assert out.palette is not None
diff --git a/docs/deprecations.rst b/docs/deprecations.rst
index 0490ba439..a5d89408b 100644
--- a/docs/deprecations.rst
+++ b/docs/deprecations.rst
@@ -193,6 +193,14 @@ Image.Image.get_child_images()
 method uses an image's file pointer, and so child images could only be retrieved from
 an :py:class:`PIL.ImageFile.ImageFile` instance.
 
+Image.fromarray mode parameter
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. deprecated:: 11.3.0
+
+The ``mode`` parameter in :py:meth:`~PIL.Image.fromarray()` has been deprecated. The
+mode can be automatically determined from the object's shape and type instead.
+
 Removed features
 ----------------
 
diff --git a/docs/releasenotes/11.3.0.rst b/docs/releasenotes/11.3.0.rst
index b0595def9..f0fa8c858 100644
--- a/docs/releasenotes/11.3.0.rst
+++ b/docs/releasenotes/11.3.0.rst
@@ -23,10 +23,11 @@ TODO
 Deprecations
 ============
 
-TODO
-^^^^
+Image.fromarray mode parameter
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-TODO
+The ``mode`` parameter in :py:meth:`~PIL.Image.fromarray()` has been deprecated. The
+mode can be automatically determined from the object's shape and type instead.
 
 API changes
 ===========
diff --git a/src/PIL/Image.py b/src/PIL/Image.py
index 7e9540e48..0be9e8ce4 100644
--- a/src/PIL/Image.py
+++ b/src/PIL/Image.py
@@ -3272,7 +3272,7 @@ def fromarray(obj: SupportsArrayInterface, mode: str | None = None) -> Image:
 
     :param obj: Object with array interface
     :param mode: Optional mode to use when reading ``obj``. Will be determined from
-      type if ``None``.
+      type if ``None``. Deprecated.
 
       This will not be used to convert the data after reading, but will be used to
       change how the data is read::
@@ -3307,6 +3307,7 @@ def fromarray(obj: SupportsArrayInterface, mode: str | None = None) -> Image:
             msg = f"Cannot handle this data type: {typekey_shape}, {typestr}"
             raise TypeError(msg) from e
     else:
+        deprecate("'mode' parameter", 13)
         rawmode = mode
     if mode in ["1", "L", "I", "P", "F"]:
         ndmax = 2