From dcd201b0e0675a2edc8b3544273cedafccc0a9ef Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Wed, 11 Jan 2017 11:14:00 +1100
Subject: [PATCH] Add scaled integer benchmarks.

---
 .../ImageSharp.Benchmarks/Color/RgbToYCbCr.cs | 48 +++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 tests/ImageSharp.Benchmarks/Color/RgbToYCbCr.cs

diff --git a/tests/ImageSharp.Benchmarks/Color/RgbToYCbCr.cs b/tests/ImageSharp.Benchmarks/Color/RgbToYCbCr.cs
new file mode 100644
index 000000000..2da7d0e44
--- /dev/null
+++ b/tests/ImageSharp.Benchmarks/Color/RgbToYCbCr.cs
@@ -0,0 +1,48 @@
+namespace ImageSharp.Benchmarks
+{
+    using System.Numerics;
+
+    using BenchmarkDotNet.Attributes;
+
+    public class RgbToYCbCr
+    {
+        [Benchmark(Baseline = true, Description = "Floating Point Conversion")]
+        public Vector3 RgbaToYcbCr()
+        {
+            Vector3 v = new Vector3(255);
+
+            float yy = (0.299F * v.X) + (0.587F * v.Y) + (0.114F * v.Z);
+            float cb = 128 + ((-0.168736F * v.X) - (0.331264F * v.Y) + (0.5F * v.Z));
+            float cr = 128 + ((0.5F * v.X) - (0.418688F * v.Y) - (0.081312F * v.Z));
+
+            return new Vector3(yy, cb, cr);
+        }
+
+        [Benchmark(Description = "Scaled Integer Conversion")]
+        public Vector3 RgbaToYcbCrScaled()
+        {
+            int r = 255;
+            int g = 255;
+            int b = 255;
+
+            // Scale by 1024 and truncate value
+            int y0 = 306 * r; // 0.299F
+            int y1 = 601 * g; // 0.587F
+            int y2 = 116 * b; // 0.114F
+
+            int cb0 = -172 * r; // -0.168736F
+            int cb1 = 339 * g; // 0.331264F
+            int cb2 = 512 * b; // 0.5F
+
+            int cr0 = 512 * r; // 0.5F
+            int cr1 = 428 * g; // 0.418688F
+            int cr2 = 83 * b; // 0.081312F
+
+            float yy = ((y0) + (y1) + (y2)) >> 10;
+            float cb = 128 + ((((cb0) - (cb1) + (cb2))) >> 10);
+            float cr = 128 + ((((cr0) - (cr1) - (cr2))) >> 10);
+
+            return new Vector3(yy, cb, cr);
+        }
+    }
+}
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