diff --git a/src/ImageSharp/PixelFormats/PixelBlenders/PorterDuffFunctions.cs b/src/ImageSharp/PixelFormats/PixelBlenders/PorterDuffFunctions.cs
index af111849a8..d1bd5bad31 100644
--- a/src/ImageSharp/PixelFormats/PixelBlenders/PorterDuffFunctions.cs
+++ b/src/ImageSharp/PixelFormats/PixelBlenders/PorterDuffFunctions.cs
@@ -102,7 +102,7 @@ internal static partial class PorterDuffFunctions
     /// <returns>The <see cref="Vector256{Single}"/>.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static Vector256<float> Subtract(Vector256<float> backdrop, Vector256<float> source)
-        => Avx.Min(Vector256.Create(1F), Avx.Subtract(backdrop, source));
+        => Avx.Max(Vector256<float>.Zero, Avx.Subtract(backdrop, source));
 
     /// <summary>
     /// Returns the result of the "Screen" compositing equation.
diff --git a/tests/ImageSharp.Tests/PixelFormats/PixelBlenders/PorterDuffFunctionsTests.cs b/tests/ImageSharp.Tests/PixelFormats/PixelBlenders/PorterDuffFunctionsTests.cs
index 02b4b0ea50..189d21f1e6 100644
--- a/tests/ImageSharp.Tests/PixelFormats/PixelBlenders/PorterDuffFunctionsTests.cs
+++ b/tests/ImageSharp.Tests/PixelFormats/PixelBlenders/PorterDuffFunctionsTests.cs
@@ -10,6 +10,8 @@ namespace SixLabors.ImageSharp.Tests.PixelFormats.PixelBlenders;
 
 public class PorterDuffFunctionsTests
 {
+    private static readonly ApproximateFloatComparer FloatComparer = new(.000001F);
+
     public static TheoryData<TestVector4, TestVector4, float, TestVector4> NormalBlendFunctionData { get; } = new()
     {
         { new TestVector4(1, 1, 1, 1), new TestVector4(1, 1, 1, 1), 1, new TestVector4(1, 1, 1, 1) },
@@ -33,7 +35,7 @@ public class PorterDuffFunctionsTests
 
         Vector256<float> expected256 = Vector256.Create(expected.X, expected.Y, expected.Z, expected.W, expected.X, expected.Y, expected.Z, expected.W);
         Vector256<float> actual = PorterDuffFunctions.NormalSrcOver(back256, source256, Vector256.Create(amount));
-        Assert.Equal(expected256, actual);
+        Assert.Equal(expected256, actual, FloatComparer);
     }
 
     public static TheoryData<TestVector4, TestVector4, float, TestVector4> MultiplyFunctionData { get; } = new()
@@ -51,21 +53,45 @@ public class PorterDuffFunctionsTests
         VectorAssert.Equal(expected, actual, 5);
     }
 
+    [Theory]
+    [MemberData(nameof(MultiplyFunctionData))]
+    public void MultiplyFunction256(TestVector4 back, TestVector4 source, float amount, TestVector4 expected)
+    {
+        Vector256<float> back256 = Vector256.Create(back.X, back.Y, back.Z, back.W, back.X, back.Y, back.Z, back.W);
+        Vector256<float> source256 = Vector256.Create(source.X, source.Y, source.Z, source.W, source.X, source.Y, source.Z, source.W);
+
+        Vector256<float> expected256 = Vector256.Create(expected.X, expected.Y, expected.Z, expected.W, expected.X, expected.Y, expected.Z, expected.W);
+        Vector256<float> actual = PorterDuffFunctions.MultiplySrcOver(back256, source256, Vector256.Create(amount));
+        Assert.Equal(expected256, actual, FloatComparer);
+    }
+
     public static TheoryData<TestVector4, TestVector4, float, TestVector4> AddFunctionData { get; } = new()
     {
         { new TestVector4(1, 1, 1, 1), new TestVector4(1, 1, 1, 1), 1, new TestVector4(1, 1, 1, 1) },
-        { new TestVector4(1, 1, 1, 1), new TestVector4(0, 0, 0, .8f), .5f, new TestVector4(.6f, .6f, .6f, 1f) },
-        { new TestVector4(0.2f, 0.2f, 0.2f, 0.3f), new TestVector4(0.3f, 0.3f, 0.3f, 0.2f), .5f, new TestVector4(.2075676f, .2075676f, .2075676f, .37f) }
+        { new TestVector4(1, 1, 1, 1), new TestVector4(0, 0, 0, .8f), .5f, new TestVector4(1, 1, 1, 1) },
+        { new TestVector4(0.2f, 0.2f, 0.2f, 0.3f), new TestVector4(0.3f, 0.3f, 0.3f, 0.2f), .5f, new TestVector4(0.24324325f, 0.24324325f, 0.24324325f, .37f) }
     };
 
     [Theory]
     [MemberData(nameof(AddFunctionData))]
     public void AddFunction(TestVector4 back, TestVector4 source, float amount, TestVector4 expected)
     {
-        Vector4 actual = PorterDuffFunctions.MultiplySrcOver((Vector4)back, source, amount);
+        Vector4 actual = PorterDuffFunctions.AddSrcOver((Vector4)back, source, amount);
         VectorAssert.Equal(expected, actual, 5);
     }
 
+    [Theory]
+    [MemberData(nameof(AddFunctionData))]
+    public void AddFunction256(TestVector4 back, TestVector4 source, float amount, TestVector4 expected)
+    {
+        Vector256<float> back256 = Vector256.Create(back.X, back.Y, back.Z, back.W, back.X, back.Y, back.Z, back.W);
+        Vector256<float> source256 = Vector256.Create(source.X, source.Y, source.Z, source.W, source.X, source.Y, source.Z, source.W);
+
+        Vector256<float> expected256 = Vector256.Create(expected.X, expected.Y, expected.Z, expected.W, expected.X, expected.Y, expected.Z, expected.W);
+        Vector256<float> actual = PorterDuffFunctions.AddSrcOver(back256, source256, Vector256.Create(amount));
+        Assert.Equal(expected256, actual, FloatComparer);
+    }
+
     public static TheoryData<TestVector4, TestVector4, float, TestVector4> SubtractFunctionData { get; } = new()
     {
         { new TestVector4(1, 1, 1, 1), new TestVector4(1, 1, 1, 1), 1, new TestVector4(0, 0, 0, 1) },
@@ -81,6 +107,18 @@ public class PorterDuffFunctionsTests
         VectorAssert.Equal(expected, actual, 5);
     }
 
+    [Theory]
+    [MemberData(nameof(SubtractFunctionData))]
+    public void SubtractFunction256(TestVector4 back, TestVector4 source, float amount, TestVector4 expected)
+    {
+        Vector256<float> back256 = Vector256.Create(back.X, back.Y, back.Z, back.W, back.X, back.Y, back.Z, back.W);
+        Vector256<float> source256 = Vector256.Create(source.X, source.Y, source.Z, source.W, source.X, source.Y, source.Z, source.W);
+
+        Vector256<float> expected256 = Vector256.Create(expected.X, expected.Y, expected.Z, expected.W, expected.X, expected.Y, expected.Z, expected.W);
+        Vector256<float> actual = PorterDuffFunctions.SubtractSrcOver(back256, source256, Vector256.Create(amount));
+        Assert.Equal(expected256, actual, FloatComparer);
+    }
+
     public static TheoryData<TestVector4, TestVector4, float, TestVector4> ScreenFunctionData { get; } = new()
     {
         { new TestVector4(1, 1, 1, 1), new TestVector4(1, 1, 1, 1), 1, new TestVector4(1, 1, 1, 1) },
@@ -96,6 +134,18 @@ public class PorterDuffFunctionsTests
         VectorAssert.Equal(expected, actual, 5);
     }
 
+    [Theory]
+    [MemberData(nameof(ScreenFunctionData))]
+    public void ScreenFunction256(TestVector4 back, TestVector4 source, float amount, TestVector4 expected)
+    {
+        Vector256<float> back256 = Vector256.Create(back.X, back.Y, back.Z, back.W, back.X, back.Y, back.Z, back.W);
+        Vector256<float> source256 = Vector256.Create(source.X, source.Y, source.Z, source.W, source.X, source.Y, source.Z, source.W);
+
+        Vector256<float> expected256 = Vector256.Create(expected.X, expected.Y, expected.Z, expected.W, expected.X, expected.Y, expected.Z, expected.W);
+        Vector256<float> actual = PorterDuffFunctions.ScreenSrcOver(back256, source256, Vector256.Create(amount));
+        Assert.Equal(expected256, actual, FloatComparer);
+    }
+
     public static TheoryData<TestVector4, TestVector4, float, TestVector4> DarkenFunctionData { get; } = new()
     {
         { new TestVector4(1, 1, 1, 1), new TestVector4(1, 1, 1, 1), 1, new TestVector4(1, 1, 1, 1) },
@@ -111,6 +161,18 @@ public class PorterDuffFunctionsTests
         VectorAssert.Equal(expected, actual, 5);
     }
 
+    [Theory]
+    [MemberData(nameof(DarkenFunctionData))]
+    public void DarkenFunction256(TestVector4 back, TestVector4 source, float amount, TestVector4 expected)
+    {
+        Vector256<float> back256 = Vector256.Create(back.X, back.Y, back.Z, back.W, back.X, back.Y, back.Z, back.W);
+        Vector256<float> source256 = Vector256.Create(source.X, source.Y, source.Z, source.W, source.X, source.Y, source.Z, source.W);
+
+        Vector256<float> expected256 = Vector256.Create(expected.X, expected.Y, expected.Z, expected.W, expected.X, expected.Y, expected.Z, expected.W);
+        Vector256<float> actual = PorterDuffFunctions.DarkenSrcOver(back256, source256, Vector256.Create(amount));
+        Assert.Equal(expected256, actual, FloatComparer);
+    }
+
     public static TheoryData<TestVector4, TestVector4, float, TestVector4> LightenFunctionData { get; } = new()
     {
         { new TestVector4(1, 1, 1, 1), new TestVector4(1, 1, 1, 1), 1, new TestVector4(1, 1, 1, 1) },
@@ -126,6 +188,18 @@ public class PorterDuffFunctionsTests
         VectorAssert.Equal(expected, actual, 5);
     }
 
+    [Theory]
+    [MemberData(nameof(LightenFunctionData))]
+    public void LightenFunction256(TestVector4 back, TestVector4 source, float amount, TestVector4 expected)
+    {
+        Vector256<float> back256 = Vector256.Create(back.X, back.Y, back.Z, back.W, back.X, back.Y, back.Z, back.W);
+        Vector256<float> source256 = Vector256.Create(source.X, source.Y, source.Z, source.W, source.X, source.Y, source.Z, source.W);
+
+        Vector256<float> expected256 = Vector256.Create(expected.X, expected.Y, expected.Z, expected.W, expected.X, expected.Y, expected.Z, expected.W);
+        Vector256<float> actual = PorterDuffFunctions.LightenSrcOver(back256, source256, Vector256.Create(amount));
+        Assert.Equal(expected256, actual, FloatComparer);
+    }
+
     public static TheoryData<TestVector4, TestVector4, float, TestVector4> OverlayFunctionData { get; } = new()
     {
         { new TestVector4(1, 1, 1, 1), new TestVector4(1, 1, 1, 1), 1, new TestVector4(1, 1, 1, 1) },
@@ -141,6 +215,18 @@ public class PorterDuffFunctionsTests
         VectorAssert.Equal(expected, actual, 5);
     }
 
+    [Theory]
+    [MemberData(nameof(OverlayFunctionData))]
+    public void OverlayFunction256(TestVector4 back, TestVector4 source, float amount, TestVector4 expected)
+    {
+        Vector256<float> back256 = Vector256.Create(back.X, back.Y, back.Z, back.W, back.X, back.Y, back.Z, back.W);
+        Vector256<float> source256 = Vector256.Create(source.X, source.Y, source.Z, source.W, source.X, source.Y, source.Z, source.W);
+
+        Vector256<float> expected256 = Vector256.Create(expected.X, expected.Y, expected.Z, expected.W, expected.X, expected.Y, expected.Z, expected.W);
+        Vector256<float> actual = PorterDuffFunctions.OverlaySrcOver(back256, source256, Vector256.Create(amount));
+        Assert.Equal(expected256, actual, FloatComparer);
+    }
+
     public static TheoryData<TestVector4, TestVector4, float, TestVector4> HardLightFunctionData { get; } = new()
     {
         { new TestVector4(1, 1, 1, 1), new TestVector4(1, 1, 1, 1), 1, new TestVector4(1, 1, 1, 1) },
@@ -155,4 +241,16 @@ public class PorterDuffFunctionsTests
         Vector4 actual = PorterDuffFunctions.HardLightSrcOver((Vector4)back, source, amount);
         VectorAssert.Equal(expected, actual, 5);
     }
+
+    [Theory]
+    [MemberData(nameof(HardLightFunctionData))]
+    public void HardLightFunction256(TestVector4 back, TestVector4 source, float amount, TestVector4 expected)
+    {
+        Vector256<float> back256 = Vector256.Create(back.X, back.Y, back.Z, back.W, back.X, back.Y, back.Z, back.W);
+        Vector256<float> source256 = Vector256.Create(source.X, source.Y, source.Z, source.W, source.X, source.Y, source.Z, source.W);
+
+        Vector256<float> expected256 = Vector256.Create(expected.X, expected.Y, expected.Z, expected.W, expected.X, expected.Y, expected.Z, expected.W);
+        Vector256<float> actual = PorterDuffFunctions.HardLightSrcOver(back256, source256, Vector256.Create(amount));
+        Assert.Equal(expected256, actual, FloatComparer);
+    }
 }
diff --git a/tests/ImageSharp.Tests/TestUtilities/ApproximateFloatComparer.cs b/tests/ImageSharp.Tests/TestUtilities/ApproximateFloatComparer.cs
index 6d9652d898..e35f36feec 100644
--- a/tests/ImageSharp.Tests/TestUtilities/ApproximateFloatComparer.cs
+++ b/tests/ImageSharp.Tests/TestUtilities/ApproximateFloatComparer.cs
@@ -1,7 +1,9 @@
 // Copyright (c) Six Labors.
 // Licensed under the Six Labors Split License.
 
+using System.Diagnostics.CodeAnalysis;
 using System.Numerics;
+using System.Runtime.Intrinsics;
 using SixLabors.ImageSharp.PixelFormats;
 
 namespace SixLabors.ImageSharp.Tests;
@@ -14,7 +16,8 @@ internal readonly struct ApproximateFloatComparer :
     IEqualityComparer<Vector2>,
     IEqualityComparer<IPixel>,
     IEqualityComparer<Vector4>,
-    IEqualityComparer<ColorMatrix>
+    IEqualityComparer<ColorMatrix>,
+    IEqualityComparer<Vector256<float>>
 {
     private readonly float epsilon;
 
@@ -72,4 +75,16 @@ internal readonly struct ApproximateFloatComparer :
 
     /// <inheritdoc/>
     public int GetHashCode(ColorMatrix obj) => obj.GetHashCode();
+
+    public bool Equals(Vector256<float> x, Vector256<float> y)
+        => this.Equals(x.GetElement(0), y.GetElement(0))
+        && this.Equals(x.GetElement(1), y.GetElement(1))
+        && this.Equals(x.GetElement(2), y.GetElement(2))
+        && this.Equals(x.GetElement(3), y.GetElement(3))
+        && this.Equals(x.GetElement(4), y.GetElement(4))
+        && this.Equals(x.GetElement(5), y.GetElement(5))
+        && this.Equals(x.GetElement(6), y.GetElement(6))
+        && this.Equals(x.GetElement(7), y.GetElement(7));
+
+    public int GetHashCode([DisallowNull] Vector256<float> obj) => obj.GetHashCode();
 }