Add 'DecodeTiff' benchmark

tests/ImageSharp.Benchmarks/BenchmarkBase.cs

@@ -17,6 +17,7 @@
             Configuration.Default.AddImageFormat(new PngFormat());
             Configuration.Default.AddImageFormat(new BmpFormat());
             Configuration.Default.AddImageFormat(new GifFormat());
+            Configuration.Default.AddImageFormat(new TiffFormat());
         }
     }
 }

tests/ImageSharp.Benchmarks/Image/DecodeTiff.cs

@@ -0,0 +1,54 @@
+// <copyright file="DecodeTiff.cs" company="James Jackson-South">
+// Copyright (c) James Jackson-South and contributors.
+// Licensed under the Apache License, Version 2.0.
+// </copyright>
+
+namespace ImageSharp.Benchmarks.Image
+{
+    using System.Drawing;
+    using System.IO;
+
+    using BenchmarkDotNet.Attributes;
+
+    using CoreImage = ImageSharp.Image;
+
+    using CoreSize = ImageSharp.Size;
+
+    public class DecodeTiff : BenchmarkBase
+    {
+        private byte[] tiffBytes;
+
+        [GlobalSetup]
+        public void ReadImages()
+        {
+            if (this.tiffBytes == null)
+            {
+                this.tiffBytes = File.ReadAllBytes("../ImageSharp.Tests/TestImages/Formats/Tiff/Calliphora_rgb_uncompressed.tiff");
+            }
+        }
+
+        [Benchmark(Baseline = true, Description = "System.Drawing Tiff")]
+        public Size TiffSystemDrawing()
+        {
+            using (MemoryStream memoryStream = new MemoryStream(this.tiffBytes))
+            {
+                using (Image image = Image.FromStream(memoryStream))
+                {
+                    return image.Size;
+                }
+            }
+        }
+
+        [Benchmark(Description = "ImageSharp Tiff")]
+        public CoreSize TiffCore()
+        {
+            using (MemoryStream memoryStream = new MemoryStream(this.tiffBytes))
+            {
+                using (Image<Rgba32> image = CoreImage.Load<Rgba32>(memoryStream))
+                {
+                    return new CoreSize(image.Width, image.Height);
+                }
+            }
+        }
+    }
+}