Added color-extension to calculate the distance between two colors

RGB.NET.Core/Extensions/ColorExtensions.cs

@@ -0,0 +1,30 @@
+using System;
+
+namespace RGB.NET.Core
+{
+    public static class ColorExtensions
+    {
+        #region Methods
+
+        /// <summary>
+        /// Calculates the distance between the two given colors using the redmean algorithm.
+        /// For more infos check https://www.compuphase.com/cmetric.htm
+        /// </summary>
+        /// <param name="color1">The start color of the distance calculation.</param>
+        /// <param name="color2">The end color fot the distance calculation.</param>
+        /// <returns></returns>
+        public static double DistanceTo(this Color color1, Color color2)
+        {
+            (_, byte r1, byte g1, byte b1) = color1.GetRGBBytes();
+            (_, byte r2, byte g2, byte b2) = color2.GetRGBBytes();
+
+            long rmean = (r1 + r2) / 2;
+            long r = r1 - r2;
+            long g = g1 - g2;
+            long b = b1 - b2;
+            return Math.Sqrt((((512 + rmean) * r * r) >> 8) + (4 * g * g) + (((767 - rmean) * b * b) >> 8));
+        }
+
+        #endregion
+    }
+}