Refactoring the rest to use a const epsilon.

src/ImageSharp/Drawing/Processors/FillShapeProcessor.cs

@@ -8,6 +8,7 @@ namespace ImageSharp.Drawing.Processors
     using System;
     using System.Numerics;
     using System.Threading.Tasks;
+    using Common;
     using Drawing;
     using ImageSharp.Processors;
     using Shapes;
@@ -21,8 +22,6 @@ namespace ImageSharp.Drawing.Processors
     public class FillShapeProcessor<TColor> : ImageFilteringProcessor<TColor>
         where TColor : struct, IPackedPixel, IEquatable<TColor>
     {
-        private const float Epsilon = 0.001f;
-
         private const float AntialiasFactor = 1f;
         private const int DrawPadding = 1;
         private readonly IBrush<TColor> fillColor;
@@ -95,7 +94,7 @@ namespace ImageSharp.Drawing.Processors
                         float dist = this.poly.Distance(currentPoint);
                         float opacity = this.Opacity(dist);
 
-                        if (opacity > Epsilon)
+                        if (opacity > Constants.Epsilon)
                         {
                             Vector4 backgroundVector = sourcePixels[offsetX, offsetY].ToVector4();
                             Vector4 sourceVector = applicator.GetColor(currentPoint).ToVector4();

src/ImageSharp/Filters/Processors/Effects/BackgroundColorProcessor.cs

@@ -8,6 +8,7 @@ namespace ImageSharp.Processors
     using System;
     using System.Numerics;
     using System.Threading.Tasks;
+    using Common;
 
     /// <summary>
     /// Sets the background color of the image.
@@ -16,11 +17,6 @@ namespace ImageSharp.Processors
     public class BackgroundColorProcessor<TColor> : ImageFilteringProcessor<TColor>
         where TColor : struct, IPackedPixel, IEquatable<TColor>
     {
-        /// <summary>
-        /// The epsilon for comparing floating point numbers.
-        /// </summary>
-        private const float Epsilon = 0.001f;
-
         /// <summary>
         /// Initializes a new instance of the <see cref="BackgroundColorProcessor{TColor}"/> class.
         /// </summary>
@@ -82,7 +78,7 @@ namespace ImageSharp.Processors
                                 color = Vector4BlendTransforms.PremultipliedLerp(backgroundColor, color, .5F);
                             }
 
-                            if (Math.Abs(a) < Epsilon)
+                            if (Math.Abs(a) < Constants.Epsilon)
                             {
                                 color = backgroundColor;
                             }

src/ImageSharp/Filters/Processors/Transforms/RotateProcessor.cs

@@ -8,6 +8,7 @@ namespace ImageSharp.Processors
     using System;
     using System.Numerics;
     using System.Threading.Tasks;
+    using Common;
 
     /// <summary>
     /// Provides methods that allow the rotating of images.
@@ -70,9 +71,7 @@ namespace ImageSharp.Processors
         /// <inheritdoc/>
         protected override void BeforeApply(ImageBase<TColor> source, Rectangle sourceRectangle)
         {
-            const float Epsilon = .0001F;
-
-            if (Math.Abs(this.Angle) < Epsilon || Math.Abs(this.Angle - 90) < Epsilon || Math.Abs(this.Angle - 180) < Epsilon || Math.Abs(this.Angle - 270) < Epsilon)
+            if (Math.Abs(this.Angle) < Constants.Epsilon || Math.Abs(this.Angle - 90) < Constants.Epsilon || Math.Abs(this.Angle - 180) < Constants.Epsilon || Math.Abs(this.Angle - 270) < Constants.Epsilon)
             {
                 return;
             }
@@ -91,26 +90,25 @@ namespace ImageSharp.Processors
         /// <returns>The <see cref="bool"/></returns>
         private bool OptimizedApply(ImageBase<TColor> source)
         {
-            const float Epsilon = .0001F;
-            if (Math.Abs(this.Angle) < Epsilon)
+            if (Math.Abs(this.Angle) < Constants.Epsilon)
             {
                 // No need to do anything so return.
                 return true;
             }
 
-            if (Math.Abs(this.Angle - 90) < Epsilon)
+            if (Math.Abs(this.Angle - 90) < Constants.Epsilon)
             {
                 this.Rotate90(source);
                 return true;
             }
 
-            if (Math.Abs(this.Angle - 180) < Epsilon)
+            if (Math.Abs(this.Angle - 180) < Constants.Epsilon)
             {
                 this.Rotate180(source);
                 return true;
             }
 
-            if (Math.Abs(this.Angle - 270) < Epsilon)
+            if (Math.Abs(this.Angle - 270) < Constants.Epsilon)
             {
                 this.Rotate270(source);
                 return true;

src/ImageSharp/Quantizers/Wu/WuQuantizer.cs

@@ -9,6 +9,7 @@ namespace ImageSharp.Quantizers
     using System.Buffers;
     using System.Numerics;
     using System.Threading.Tasks;
+    using Common;
 
     /// <summary>
     /// An implementation of Wu's color quantizer with alpha channel.
@@ -33,11 +34,6 @@ namespace ImageSharp.Quantizers
     public sealed class WuQuantizer<TColor> : IQuantizer<TColor>
         where TColor : struct, IPackedPixel, IEquatable<TColor>
     {
-        /// <summary>
-        /// The epsilon for comparing floating point numbers.
-        /// </summary>
-        private const float Epsilon = 1e-5F;
-
         /// <summary>
         /// The index bits.
         /// </summary>
@@ -542,7 +538,7 @@ namespace ImageSharp.Quantizers
 
                 double temp;
 
-                if (Math.Abs(halfW) < Epsilon)
+                if (Math.Abs(halfW) < Constants.Epsilon)
                 {
                     continue;
                 }
@@ -555,7 +551,7 @@ namespace ImageSharp.Quantizers
                 halfA = wholeA - halfA;
                 halfW = wholeW - halfW;
 
-                if (Math.Abs(halfW) < Epsilon)
+                if (Math.Abs(halfW) < Constants.Epsilon)
                 {
                     continue;
                 }
@@ -762,7 +758,7 @@ namespace ImageSharp.Quantizers
 
                 double weight = Volume(cube[k], this.vwt);
 
-                if (Math.Abs(weight) > Epsilon)
+                if (Math.Abs(weight) > Constants.Epsilon)
                 {
                     float r = (float)(Volume(cube[k], this.vmr) / weight);
                     float g = (float)(Volume(cube[k], this.vmg) / weight);