Clean up usings and add comments

src/ImageSharp/Image.Decode.cs

@@ -5,12 +5,9 @@
 
 namespace ImageSharp
 {
-    using System;
     using System.Buffers;
-    using System.Diagnostics;
     using System.IO;
     using System.Linq;
-    using System.Text;
     using Formats;
 
     /// <summary>
@@ -19,8 +16,15 @@ namespace ImageSharp
     /// </summary>
     public sealed partial class Image
     {
+        /// <summary>
+        /// By reading the header on the provided stream this calculates the images format.
+        /// </summary>
+        /// <param name="stream">The image stream to read the header from.</param>
+        /// <param name="config">The configuration.</param>
+        /// <returns>The image format or null if none found.</returns>
         private static IImageFormat DiscoverFormat(Stream stream, Configuration config)
         {
+            // This is probably a candidate for making into a public API in the future!
             int maxHeaderSize = config.MaxHeaderSize;
             if (maxHeaderSize <= 0)
             {

src/ImageSharp/Image.FromBytes.cs

@@ -6,11 +6,7 @@
 namespace ImageSharp
 {
     using System;
-    using System.Buffers;
-    using System.Diagnostics;
     using System.IO;
-    using System.Linq;
-    using System.Text;
     using Formats;
 
     /// <summary>

src/ImageSharp/Image.FromFile.cs

@@ -5,15 +5,11 @@
 
 namespace ImageSharp
 {
+#if !NETSTANDARD1_1
     using System;
-    using System.Buffers;
-    using System.Diagnostics;
     using System.IO;
-    using System.Linq;
-    using System.Text;
     using Formats;
 
-#if !NETSTANDARD1_1
     /// <summary>
     /// Represents an image. Each pixel is a made up four 8-bit components red, green, blue, and alpha
     /// packed into a single unsigned integer value.

src/ImageSharp/Image.FromStream.cs

@@ -6,10 +6,7 @@
 namespace ImageSharp
 {
     using System;
-    using System.Buffers;
-    using System.Diagnostics;
     using System.IO;
-    using System.Linq;
     using System.Text;
     using Formats;
 
@@ -86,7 +83,9 @@ namespace ImageSharp
         /// <returns>The image</returns>
         public static Image Load(Stream stream, IDecoderOptions options, Configuration config)
         {
-            return new Image(Load<Color>(stream, options, config));
+            Image<Color> image = Load<Color>(stream, options, config);
+
+            return image as Image ?? new Image(image);
         }
 
         /// <summary>
@@ -101,7 +100,9 @@ namespace ImageSharp
         /// <returns>The image</returns>
         public static Image Load(Stream stream, IImageDecoder decoder, IDecoderOptions options)
         {
-            return new Image(Load<Color>(stream, decoder, options));
+            Image<Color> image = new Image(Load<Color>(stream, decoder, options));
+
+            return image as Image ?? new Image(image);
         }
 
         /// <summary>
@@ -200,10 +201,7 @@ namespace ImageSharp
         {
             config = config ?? Configuration.Default;
 
-            Image<TColor> img = WithSeekableStream(stream, s =>
-            {
-                return Decode<TColor>(stream, options, config);
-            });
+            Image<TColor> img = WithSeekableStream(stream, s => Decode<TColor>(stream, options, config));
 
             if (img != null)
             {