update image encoding

MediaBrowser.Api/Images/ImageService.cs

@@ -1,5 +1,4 @@
 using MediaBrowser.Common.Extensions;
-using MediaBrowser.Common.IO;
 using MediaBrowser.Controller.Drawing;
 using MediaBrowser.Controller.Entities;
 using MediaBrowser.Controller.Library;
@@ -18,7 +17,6 @@ using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using CommonIO;
-using MimeTypes = MediaBrowser.Model.Net.MimeTypes;
 
 namespace MediaBrowser.Api.Images
 {