Improve method name

Added comments too

tests/ImageSharp.Tests/Formats/Png/PngSmokeTests.cs

@@ -32,7 +32,7 @@ namespace ImageSharp.Tests.Formats.Png
                 using (Image img2 = new Image(ms, new Configuration(new PngFormat())))
                 {
                     // img2.Save(provider.Utility.GetTestOutputFileName("bmp", "_loaded"), new BmpEncoder());
-                    ImageComparer.VisualComparer(image, img2);
+                    ImageComparer.CheckSimilarity(image, img2);
                 }
             }
         }
@@ -53,7 +53,7 @@ namespace ImageSharp.Tests.Formats.Png
                 using (Image img2 = new Image(ms, new Configuration(new PngFormat())))
                 {
                     // img2.Save(provider.Utility.GetTestOutputFileName("bmp", "_loaded"), new BmpEncoder());
-                    ImageComparer.VisualComparer(image, img2);
+                    ImageComparer.CheckSimilarity(image, img2);
                 }
             }
         }
@@ -75,7 +75,7 @@ namespace ImageSharp.Tests.Formats.Png
                 ms.Position = 0;
                 using (Image img2 = new Image(ms, new Configuration(new PngFormat())))
                 {
-                    ImageComparer.VisualComparer(image, img2);
+                    ImageComparer.CheckSimilarity(image, img2);
                 }
             }
         }

tests/ImageSharp.Tests/ImageComparer.cs

@@ -32,7 +32,7 @@
         /// This is a sampling factor we sample a grid of average pixels <paramref name="scalingFactor"/> width by <paramref name="scalingFactor"/> high
         /// The default undefined value is <see cref="ImageComparer.DefaultScalingFactor"/>
         /// </param>
-        public static void VisualComparer<TColorA, TColorB>(Image<TColorA> expected, Image<TColorB> actual, float imageTheshold = DefaultImageThreshold, byte segmentThreshold = DefaultSegmentThreshold, int scalingFactor = DefaultScalingFactor)
+        public static void CheckSimilarity<TColorA, TColorB>(Image<TColorA> expected, Image<TColorB> actual, float imageTheshold = DefaultImageThreshold, byte segmentThreshold = DefaultSegmentThreshold, int scalingFactor = DefaultScalingFactor)
            where TColorA : struct, IPixel<TColorA>
            where TColorB : struct, IPixel<TColorB>
         {

tests/ImageSharp.Tests/TestUtilities/ImageProviders/TestPatternProvider.cs

@@ -12,6 +12,11 @@ namespace ImageSharp.Tests
     public abstract partial class TestImageProvider<TColor>
         where TColor : struct, IPixel<TColor>
     {
+
+        /// <summary>
+        /// A test image provider that produces test patterns.
+        /// </summary>
+        /// <typeparam name="TColor"></typeparam>
         private class TestPatternProvider : TestImageProvider<TColor>
         {
             static Dictionary<string, Image<TColor>> testImages = new Dictionary<string, Image<TColor>>();
@@ -43,19 +48,26 @@ namespace ImageSharp.Tests
                 }
             }
 
+            /// <summary>
+            /// Draws the test pattern on an image by drawing 4 other patterns in the for quadrants of the image.
+            /// </summary>
+            /// <param name="image"></param>
             private static void DrawTestPattern(Image<TColor> image)
             {
                 // first lets split the image into 4 quadrants
                 using (PixelAccessor<TColor> pixels = image.Lock())
                 {
                     BlackWhiteChecker(pixels); // top left
-                    HorizontalLines(pixels); // top right
+                    VirticalBars(pixels); // top right
                     TransparentGradients(pixels); // bottom left
-                    Raninbow(pixels); // bottom right 
+                    Rainbow(pixels); // bottom right 
                 }
             }
-
-            private static void HorizontalLines(PixelAccessor<TColor> pixels)
+            /// <summary>
+            /// Fills the top right quadrant with alternating solid vertical bars.
+            /// </summary>
+            /// <param name="pixels"></param>
+            private static void VirticalBars(PixelAccessor<TColor> pixels)
             {
                 // topLeft 
                 int left = pixels.Width / 2;
@@ -82,6 +94,10 @@ namespace ImageSharp.Tests
                 }
             }
 
+            /// <summary>
+            /// fills the top left quadrant with a black and white checker board.
+            /// </summary>
+            /// <param name="pixels"></param>
             private static void BlackWhiteChecker(PixelAccessor<TColor> pixels)
             {
                 // topLeft 
@@ -116,7 +132,11 @@ namespace ImageSharp.Tests
                     p = pstart;
                 }
             }
-
+            
+            /// <summary>
+            /// Fills the bottom left quadrent with 3 horizental bars in Red, Green and Blue with a alpha gradient from left (transparent) to right (solid).
+            /// </summary>
+            /// <param name="pixels"></param>
             private static void TransparentGradients(PixelAccessor<TColor> pixels)
             {
                 // topLeft 
@@ -155,9 +175,14 @@ namespace ImageSharp.Tests
                         pixels[x, y] = c;
                     }
                 }
-
             }
-            private static void Raninbow(PixelAccessor<TColor> pixels)
+
+            /// <summary>
+            /// Fills the bottom right quadrant with all the colors producable by converting itterating over a uint and unpacking it.
+            /// A better algorithm could be used but it works
+            /// </summary>
+            /// <param name="pixels"></param>
+            private static void Rainbow(PixelAccessor<TColor> pixels)
             {
                 int left = pixels.Width / 2;
                 int right = pixels.Width;