From 88dc42ff50e849acf4fabf5c0dbeffb72ebdf3c0 Mon Sep 17 00:00:00 2001
From: nyxst4ck <289980115+nyxst4ck@users.noreply.github.com>
Date: Tue, 16 Jun 2026 20:00:31 -0300
Subject: [PATCH 1/2] Fix IFDRational.__float__ returning the wrong value

IFDRational delegates __eq__, __int__, __round__, __repr__ and arithmetic to
self._val (the normalized Fraction), but never defined __float__. For a
non-integral numerator (e.g. IFDRational(1.5, 3), whose value is 0.5) float()
fell back to numbers.Rational.__float__, which computes
int(numerator) / int(denominator) = int(1.5) / int(3) = 0.333..., disagreeing
with ==, int() and repr() (all 0.5).

Delegate __float__ to self._val so float() is consistent with the rest of the
class.
---
 Tests/test_tiff_ifdrational.py | 15 +++++++++++++++
 src/PIL/TiffImagePlugin.py     |  1 +
 2 files changed, 16 insertions(+)

diff --git a/Tests/test_tiff_ifdrational.py b/Tests/test_tiff_ifdrational.py
index 42d06b89696..93501351d76 100644
--- a/Tests/test_tiff_ifdrational.py
+++ b/Tests/test_tiff_ifdrational.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import math
 from fractions import Fraction
 from pathlib import Path
 
@@ -38,6 +39,20 @@ def test_sanity() -> None:
     _test_equal(7, 5, 1.4)
 
 
+def test_float() -> None:
+    # float() must agree with ==, int() and repr(), which all use the
+    # normalized fraction. For a non-integral numerator (1.5 / 3 == 0.5) the
+    # inherited Rational.__float__ used int(numerator) / int(denominator) and
+    # returned 1/3 instead.
+    r = IFDRational(1.5, 3)
+    assert r == 0.5
+    assert float(r) == 0.5
+
+    # Integral and 0/0 (nan) cases stay correct.
+    assert float(IFDRational(4, 2)) == 2.0
+    assert math.isnan(float(IFDRational(0, 0)))
+
+
 def test_ranges() -> None:
     for num in range(1, 10):
         for denom in range(1, 10):
diff --git a/src/PIL/TiffImagePlugin.py b/src/PIL/TiffImagePlugin.py
index 5094faa1325..02ce330d034 100644
--- a/src/PIL/TiffImagePlugin.py
+++ b/src/PIL/TiffImagePlugin.py
@@ -464,6 +464,7 @@ def __setstate__(self, state: list[float | Fraction | IntegralLike]) -> None:
     __ceil__ = _delegate("__ceil__")
     __floor__ = _delegate("__floor__")
     __round__ = _delegate("__round__")
+    __float__ = _delegate("__float__")
     # Python >= 3.11
     if hasattr(Fraction, "__int__"):
         __int__ = _delegate("__int__")

From 2e093e445b2e6daf27302fb5ec871474a179a271 Mon Sep 17 00:00:00 2001
From: Andrew Murray <3112309+radarhere@users.noreply.github.com>
Date: Fri, 19 Jun 2026 19:19:08 +1000
Subject: [PATCH 2/2] Updated comments

Co-authored-by: Andrew Murray <3112309+radarhere@users.noreply.github.com>
---
 Tests/test_tiff_ifdrational.py | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/Tests/test_tiff_ifdrational.py b/Tests/test_tiff_ifdrational.py
index 93501351d76..8cf48ba7dc6 100644
--- a/Tests/test_tiff_ifdrational.py
+++ b/Tests/test_tiff_ifdrational.py
@@ -41,14 +41,12 @@ def test_sanity() -> None:
 
 def test_float() -> None:
     # float() must agree with ==, int() and repr(), which all use the
-    # normalized fraction. For a non-integral numerator (1.5 / 3 == 0.5) the
-    # inherited Rational.__float__ used int(numerator) / int(denominator) and
-    # returned 1/3 instead.
+    # normalized fraction
     r = IFDRational(1.5, 3)
     assert r == 0.5
     assert float(r) == 0.5
 
-    # Integral and 0/0 (nan) cases stay correct.
+    # Integer numerator and 0/0 (nan) cases
     assert float(IFDRational(4, 2)) == 2.0
     assert math.isnan(float(IFDRational(0, 0)))