Update FromPixel

src/ImageSharp/Color/Color.Conversions.cs

@@ -23,6 +23,17 @@ namespace SixLabors.ImageSharp
             this.boxedHighPrecisionPixel = null;
         }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Color"/> struct.
+        /// </summary>
+        /// <param name="pixel">The <see cref="Rgb48"/> containing the color information.</param>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public Color(Rgb48 pixel)
+        {
+            this.data = new Rgba64(pixel.R, pixel.G, pixel.B, ushort.MaxValue);
+            this.boxedHighPrecisionPixel = null;
+        }
+
         /// <summary>
         /// Initializes a new instance of the <see cref="Color"/> struct.
         /// </summary>

src/ImageSharp/Color/Color.cs

@@ -107,7 +107,27 @@ namespace SixLabors.ImageSharp
         [MethodImpl(InliningOptions.ShortMethod)]
         public static Color FromPixel<TPixel>(TPixel pixel)
             where TPixel : unmanaged, IPixel<TPixel>
-            => new(pixel);
+        {
+            // Avoid boxing in case we can convert to Rgba64 safely and efficently
+            if (typeof(TPixel) == typeof(Rgba64))
+            {
+                return new((Rgba64)(object)pixel);
+            }
+            else if (typeof(TPixel) == typeof(Rgb48))
+            {
+                return new((Rgb48)(object)pixel);
+            }
+            else if (Unsafe.SizeOf<TPixel>() <= Unsafe.SizeOf<Rgba32>())
+            {
+                Rgba32 p = default;
+                pixel.ToRgba32(ref p);
+                return new(p);
+            }
+            else
+            {
+                return new(pixel);
+            }
+        }
 
         /// <summary>
         /// Creates a new instance of the <see cref="Color"/> struct