From fce6c8cc7e17c0f09118ed06b9063de3ff762f74 Mon Sep 17 00:00:00 2001
From: qodelicious <162776175+qodelicious@users.noreply.github.com>
Date: Thu, 5 Nov 2026 05:23:14 +0000
Subject: [PATCH 1/2] Fix converting images with transparency to PA

---
 Tests/test_image_convert.py | 14 ++++++++++++++
 src/PIL/Image.py            |  8 ++++++++
 2 files changed, 22 insertions(+)

diff --git a/Tests/test_image_convert.py b/Tests/test_image_convert.py
index a4c5490102f..f8b28eb86c4 100644
--- a/Tests/test_image_convert.py
+++ b/Tests/test_image_convert.py
@@ -317,6 +317,20 @@ def test_p2pa_palette() -> None:
     assert im_pa.getpalette(None) == im.getpalette()
 
 
+@pytest.mark.parametrize(
+    "mode, value",
+    (("1", 255), ("L", 128), ("I", 0x1234), ("I;16", 0x1234), ("RGB", (1, 2, 3))),
+)
+def test_trns_to_pa(mode: str, value: int | tuple[int, int, int]) -> None:
+    im = Image.new(mode, (2, 1))
+    im.putpixel((1, 0), value)
+    im.info["transparency"] = value
+
+    im_pa = im.convert("PA")
+    assert "transparency" not in im_pa.info
+    assert im_pa.getchannel("A").get_flattened_data() == (255, 0)
+
+
 rgb2xyz_matrix = (
     0.412453, 0.357580, 0.180423, 0,
     0.212671, 0.715160, 0.072169, 0,
diff --git a/src/PIL/Image.py b/src/PIL/Image.py
index c76bebcfb94..72f57904578 100644
--- a/src/PIL/Image.py
+++ b/src/PIL/Image.py
@@ -1198,6 +1198,14 @@ def convert_transparency(
                 else:
                     msg = "Transparency for P mode should be bytes or int"
                     raise ValueError(msg)
+            elif self.mode in {"1", "L", "I", "I;16", "RGB"} and mode == "PA":
+                # Use the transparency for the alpha channel
+                alpha = self.convert("RGBA").getchannel("A")
+                im_without_trns = self.copy()
+                del im_without_trns.info["transparency"]
+                new_im = im_without_trns.convert(mode, dither=dither)
+                new_im.putalpha(alpha)
+                return new_im
 
         if mode == "P" and palette == Palette.ADAPTIVE:
             im = self.im.quantize(colors)

From c798abce587786e6b39c5103abf7c4991e4c2b2c Mon Sep 17 00:00:00 2001
From: Andrew Murray <radarhere@users.noreply.github.com>
Date: Fri, 6 Nov 2026 14:05:58 +1100
Subject: [PATCH 2/2] Rearrange code

---
 Tests/test_image_convert.py | 2 +-
 src/PIL/Image.py            | 4 +---
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/Tests/test_image_convert.py b/Tests/test_image_convert.py
index f8b28eb86c4..7a8a9e78c89 100644
--- a/Tests/test_image_convert.py
+++ b/Tests/test_image_convert.py
@@ -319,7 +319,7 @@ def test_p2pa_palette() -> None:
 
 @pytest.mark.parametrize(
     "mode, value",
-    (("1", 255), ("L", 128), ("I", 0x1234), ("I;16", 0x1234), ("RGB", (1, 2, 3))),
+    (("1", 255), ("L", 128), ("RGB", (1, 2, 3)), ("I;16", 0x1234), ("I", 0x12345)),
 )
 def test_trns_to_pa(mode: str, value: int | tuple[int, int, int]) -> None:
     im = Image.new(mode, (2, 1))
diff --git a/src/PIL/Image.py b/src/PIL/Image.py
index 72f57904578..8c837a5f661 100644
--- a/src/PIL/Image.py
+++ b/src/PIL/Image.py
@@ -1199,12 +1199,10 @@ def convert_transparency(
                     msg = "Transparency for P mode should be bytes or int"
                     raise ValueError(msg)
             elif self.mode in {"1", "L", "I", "I;16", "RGB"} and mode == "PA":
-                # Use the transparency for the alpha channel
-                alpha = self.convert("RGBA").getchannel("A")
                 im_without_trns = self.copy()
                 del im_without_trns.info["transparency"]
                 new_im = im_without_trns.convert(mode, dither=dither)
-                new_im.putalpha(alpha)
+                new_im.putalpha(self.convert("RGBA").getchannel("A"))
                 return new_im
 
         if mode == "P" and palette == Palette.ADAPTIVE: