Add BokehBlur benchmark

tests/ImageSharp.Benchmarks/Samplers/BokehBlur.cs

@@ -0,0 +1,22 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using BenchmarkDotNet.Attributes;
+using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Processing;
+
+namespace SixLabors.ImageSharp.Benchmarks.Samplers
+{
+    [Config(typeof(Config.MultiFramework))]
+    public class BokehBlur
+    {
+        [Benchmark]
+        public void Blur()
+        {
+            using (var image = new Image<Rgba32>(Configuration.Default, 400, 400, Color.White))
+            {
+                image.Mutate(c => c.BokehBlur());
+            }
+        }
+    }
+}