diff --git a/tests/ImageSharp.Tests/Processing/Binarization/AdaptiveThresholdTests.cs b/tests/ImageSharp.Tests/Processing/Binarization/AdaptiveThresholdTests.cs
new file mode 100644
index 000000000..309716eb5
--- /dev/null
+++ b/tests/ImageSharp.Tests/Processing/Binarization/AdaptiveThresholdTests.cs
@@ -0,0 +1,77 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using SixLabors.ImageSharp.Formats.Tga;
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Processing;
+using SixLabors.ImageSharp.Processing.Processors.Binarization;
+using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
+using Xunit;
+
+namespace SixLabors.ImageSharp.Tests.Processing.Binarization
+{
+    public class AdaptiveThresholdTests : BaseImageOperationsExtensionTest
+    {
+        [Fact]
+        public void AdaptiveThreshold_UsesDefaults_Works()
+        {
+            var expectedThresholdLimit = .85f;
+            Color expectedUpper = Color.White;
+            Color expectedLower = Color.Black;
+            this.operations.AdaptiveThreshold();
+            AdaptiveThresholdProcessor p = this.Verify<AdaptiveThresholdProcessor>();
+            Assert.Equal(expectedThresholdLimit, p.ThresholdLimit);
+            Assert.Equal(expectedUpper, p.Upper);
+            Assert.Equal(expectedLower, p.Lower);
+        }
+
+        [Fact]
+        public void AdaptiveThreshold_SettingThresholdLimit_Works()
+        {
+            var expectedThresholdLimit = .65f;
+            this.operations.AdaptiveThreshold(expectedThresholdLimit);
+            AdaptiveThresholdProcessor p = this.Verify<AdaptiveThresholdProcessor>();
+            Assert.Equal(expectedThresholdLimit, p.ThresholdLimit);
+            Assert.Equal(Color.White, p.Upper);
+            Assert.Equal(Color.Black, p.Lower);
+        }
+
+        [Fact]
+        public void AdaptiveThreshold_SettingUpperLowerThresholds_Works()
+        {
+            Color expectedUpper = Color.HotPink;
+            Color expectedLower = Color.Yellow;
+            this.operations.AdaptiveThreshold(expectedUpper, expectedLower);
+            AdaptiveThresholdProcessor p = this.Verify<AdaptiveThresholdProcessor>();
+            Assert.Equal(expectedUpper, p.Upper);
+            Assert.Equal(expectedLower, p.Lower);
+        }
+
+        [Fact]
+        public void AdaptiveThreshold_SettingUpperLowerWithThresholdLimit_Works()
+        {
+            var expectedThresholdLimit = .77f;
+            Color expectedUpper = Color.HotPink;
+            Color expectedLower = Color.Yellow;
+            this.operations.AdaptiveThreshold(expectedUpper, expectedLower, expectedThresholdLimit);
+            AdaptiveThresholdProcessor p = this.Verify<AdaptiveThresholdProcessor>();
+            Assert.Equal(expectedThresholdLimit, p.ThresholdLimit);
+            Assert.Equal(expectedUpper, p.Upper);
+            Assert.Equal(expectedLower, p.Lower);
+        }
+
+        [Theory]
+        [WithFile(TestImages.Png.Bradley01, PixelTypes.Rgba32)]
+        [WithFile(TestImages.Png.Bradley02, PixelTypes.Rgba32)]
+        public void AdaptiveThreshold_Works<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : unmanaged, IPixel<TPixel>
+        {
+            using (Image<TPixel> image = provider.GetImage())
+            {
+                image.Mutate(img => img.AdaptiveThreshold());
+                image.DebugSave(provider);
+                image.CompareToReferenceOutput(ImageComparer.Exact, provider);
+            }
+        }
+    }
+}
diff --git a/tests/ImageSharp.Tests/TestImages.cs b/tests/ImageSharp.Tests/TestImages.cs
index 272998a89..e475a7712 100644
--- a/tests/ImageSharp.Tests/TestImages.cs
+++ b/tests/ImageSharp.Tests/TestImages.cs
@@ -83,6 +83,9 @@ namespace SixLabors.ImageSharp.Tests
             public const string Ducky = "Png/ducky.png";
             public const string Rainbow = "Png/rainbow.png";
 
+            public const string Bradley01 = "Png/Bradley01.png";
+            public const string Bradley02 = "Png/Bradley02.png";
+
             // Issue 1014: https://github.com/SixLabors/ImageSharp/issues/1014
             public const string Issue1014_1 = "Png/issues/Issue_1014_1.png";
             public const string Issue1014_2 = "Png/issues/Issue_1014_2.png";
diff --git a/tests/Images/External b/tests/Images/External
index fe694a393..c04c8b73a 160000
--- a/tests/Images/External
+++ b/tests/Images/External
@@ -1 +1 @@
-Subproject commit fe694a3938bea3565071a96cb1c90c4cbc586ff9
+Subproject commit c04c8b73a99c1b198597ae640394d91ddd8e033b
diff --git a/tests/Images/Input/Png/Bradley01.png b/tests/Images/Input/Png/Bradley01.png
new file mode 100644
index 000000000..5af2913e6
--- /dev/null
+++ b/tests/Images/Input/Png/Bradley01.png
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:d7eddc690c9d50fcaca3b0045d225b08c2fb172ceff5eead1d476c4df0354d02
+size 25266
diff --git a/tests/Images/Input/Png/Bradley02.png b/tests/Images/Input/Png/Bradley02.png
new file mode 100644
index 000000000..917bf9310
--- /dev/null
+++ b/tests/Images/Input/Png/Bradley02.png
@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:a73ebf6e35d5336bdf194d5098bcbe0ad240bbd09cd357816aacb1e0e7e6a614
+size 26467