Added ToFrame method that can be used to copy the pixels and properties of a image to a new Frame.

src/ImageSharp/Image/ImageBase.cs

@@ -162,5 +162,10 @@ namespace ImageSharp
             this.Quality = other.Quality;
             this.FrameDelay = other.FrameDelay;
         }
+
+        internal virtual ImageFrame<TColor, TPacked> ToFrame()
+        {
+            return new ImageFrame<TColor, TPacked>(this);
+        }
     }
 }