Fixing bug with non-inclusive AlmostEquals.

src/ImageSharp/Colors/Spaces/CieLab.cs

@@ -169,9 +169,9 @@ namespace ImageSharp.Colors.Spaces
         {
             Vector3 result = Vector3.Abs(this.backingVector - other.backingVector);
 
-            return result.X < precision
-                && result.Y < precision
-                && result.Z < precision;
+            return result.X <= precision
+                && result.Y <= precision
+                && result.Z <= precision;
         }
     }
 }

src/ImageSharp/Colors/Spaces/CieXyz.cs

@@ -160,9 +160,9 @@ namespace ImageSharp.Colors.Spaces
         {
             Vector3 result = Vector3.Abs(this.backingVector - other.backingVector);
 
-            return result.X < precision
-                && result.Y < precision
-                && result.Z < precision;
+            return result.X <= precision
+                && result.Y <= precision
+                && result.Z <= precision;
         }
     }
 }

src/ImageSharp/Colors/Spaces/Cmyk.cs

@@ -170,10 +170,10 @@ namespace ImageSharp.Colors.Spaces
         {
             Vector4 result = Vector4.Abs(this.backingVector - other.backingVector);
 
-            return result.X < precision
-                && result.Y < precision
-                && result.Z < precision
-                && result.W < precision;
+            return result.X <= precision
+                && result.Y <= precision
+                && result.Z <= precision
+                && result.W <= precision;
         }
     }
 }

src/ImageSharp/Colors/Spaces/Hsl.cs

@@ -189,9 +189,9 @@ namespace ImageSharp.Colors.Spaces
         {
             Vector3 result = Vector3.Abs(this.backingVector - other.backingVector);
 
-            return result.X < precision
-                && result.Y < precision
-                && result.Z < precision;
+            return result.X <= precision
+                && result.Y <= precision
+                && result.Z <= precision;
         }
     }
 }

src/ImageSharp/Colors/Spaces/Hsv.cs

@@ -182,9 +182,9 @@ namespace ImageSharp.Colors.Spaces
         {
             Vector3 result = Vector3.Abs(this.backingVector - other.backingVector);
 
-            return result.X < precision
-                && result.Y < precision
-                && result.Z < precision;
+            return result.X <= precision
+                && result.Y <= precision
+                && result.Z <= precision;
         }
     }
 }

tests/ImageSharp.Tests/Colors/ColorEqualityTests.cs

@@ -181,6 +181,23 @@ namespace ImageSharp.Tests.Colors
                 { new YCbCr(100, 100, 0), new YCbCr(100, 20, 0), typeof(YCbCr) },
            };
 
+        public static readonly TheoryData<object, object, Type, float> AlmostEqualsData =
+            new TheoryData<object, object, Type, float>()
+            {
+                { new CieLab(0f, 0f, 0f), new CieLab(0f, 0f, 0f), typeof(CieLab), 0f },
+                { new CieLab(0f, 0f, 0f), new CieLab(0f, 0f, 0f), typeof(CieLab), .001f },
+                { new CieLab(0f, 0f, 0f), new CieLab(0f, 0f, 0f), typeof(CieLab), .0001f },
+                { new CieLab(0f, 0f, 0f), new CieLab(0f, 0f, 0f), typeof(CieLab), .0005f },
+                { new CieLab(0f, 0f, 0f), new CieLab(0f, .001f, 0f), typeof(CieLab), .001f },
+                { new CieLab(0f, 0f, 0f), new CieLab(0f, 0f, .0001f), typeof(CieLab), .0001f },
+                { new CieLab(0f, 0f, 0f), new CieLab(.0005f, 0f, 0f), typeof(CieLab), .0005f },
+                //{ new CieXyz(380f, 380f, 380f), null, typeof(CieXyz) },
+                //{ new Cmyk(0f, 0f, 0f, 0f), null, typeof(Cmyk) },
+                //{ new Hsl(0f, 0f, 0f), null, typeof(Hsl) },
+                //{ new Hsv(360f, 1f, 1f), null, typeof(Hsv) },
+                //{ new YCbCr(0, 0, 0), null, typeof(YCbCr) },
+            };
+
         [Theory]
         [MemberData(nameof(EqualityData))]
         [MemberData(nameof(EqualityDataColorSpaces))]
@@ -308,5 +325,23 @@ namespace ImageSharp.Tests.Colors
             // Assert
             Assert.True(notEqual);
         }
+
+        [Theory]
+        [MemberData(nameof(AlmostEqualsData))]
+        public void AlmostEquals(object first, object second, Type type, float precision)
+        {
+            // Arrange 
+            // Cast to the known object types, this is so that we can hit the 
+            // equality operator on the concrete type, otherwise it goes to the 
+            // default "object" one :) 
+            dynamic firstObject = Convert.ChangeType(first, type);
+            dynamic secondObject = Convert.ChangeType(second, type);
+
+            // Act
+            var almostEqual = firstObject.AlmostEquals(secondObject, precision);
+
+            // Assert
+            Assert.True(almostEqual);
+        }
     }
 }