diff --git a/Mk0.Software.ImageSorter/FileAssociation.cs b/Mk0.Software.ImageSorter/FileAssociation.cs
index 20aafac..b004bfa 100644
--- a/Mk0.Software.ImageSorter/FileAssociation.cs
+++ b/Mk0.Software.ImageSorter/FileAssociation.cs
@@ -27,14 +27,22 @@ namespace Mk0.Tools.FileAssociaton
             }
         }
 
-        public static void Remove(string progId, string extension, string applicationFilePath, string fileTypeDescription, string iconPath)
+        public static void Remove(string progId)
         {
-            //remove reg todo
+            bool madeChanges = false;
+            madeChanges |= RemoveAssociation(progId);
+
+            if (madeChanges)
+            {
+                SHChangeNotify(SHCNE_ASSOCCHANGED, SHCNF_FLUSH, IntPtr.Zero, IntPtr.Zero);
+            }
         }
 
-        public static void Check(string progId, string extension, string applicationFilePath, string fileTypeDescription, string iconPath)
+        public static bool Check(string progId, string applicationFilePath, string fileTypeDescription, string iconPath)
         {
-            //add or update reg todo
+            bool exists = false;
+            exists |= CheckAssociation(progId, applicationFilePath, fileTypeDescription, iconPath);
+            return exists;
         }
 
         private static bool SetAssociation(string extension, string progId, string fileTypeDescription, string applicationFilePath, string iconPath)
@@ -47,6 +55,20 @@ namespace Mk0.Tools.FileAssociaton
             return madeChanges;
         }
 
+        private static bool RemoveAssociation(string progId)
+        {
+            bool madeChanges = false;
+            madeChanges |= DeleteKeyDefaultValue($@"Software\Classes\", progId);
+            return madeChanges;
+        }
+
+        private static bool CheckAssociation(string progId, string applicationFilePath, string fileTypeDescription, string iconPath)
+        {
+            bool exists = false;
+            exists |= CheckKeyDefaultValue($@"Software\Classes\{progId}\shell\open\command", "\"" + applicationFilePath + "\" \"%1\"");
+            return exists;
+        }
+
         private static bool SetKeyDefaultValue(string keyPath, string value)
         {
             using (var key = Registry.CurrentUser.CreateSubKey(keyPath))
@@ -60,5 +82,38 @@ namespace Mk0.Tools.FileAssociaton
 
             return false;
         }
+
+        private static bool DeleteKeyDefaultValue(string keyPath, string value)
+        {
+            bool erfolg = false;
+            using (var key = Registry.CurrentUser.OpenSubKey(keyPath, writable: true))
+            {
+                if (key != null)
+                {
+                    key.DeleteSubKeyTree(value, false);
+                    erfolg = true;
+                }
+            }
+
+            return erfolg;
+        }
+
+        private static bool CheckKeyDefaultValue(string keyPath, string value)
+        {
+            bool exists = false;
+            using (var key = Registry.CurrentUser.OpenSubKey(keyPath, writable: true))
+            {
+                if (key != null)
+                {
+                    string x = (string)key.GetValue("");
+                    if (!string.IsNullOrEmpty(x) && x == value)
+                    {
+                        exists = true;
+                    }
+                }
+            }
+
+            return exists;
+        }
     }
 }
diff --git a/Mk0.Software.ImageSorter/Main.cs b/Mk0.Software.ImageSorter/Main.cs
index 3b69fc2..41dccfd 100644
--- a/Mk0.Software.ImageSorter/Main.cs
+++ b/Mk0.Software.ImageSorter/Main.cs
@@ -53,7 +53,22 @@ namespace Mk0.Software.ImageSorter
             SetDefaultPath();
             comboBoxZoom.SelectedIndex = Properties.Settings.Default.zoom;
 
-            //todo file assoc prüfen und in einstellungen richtig setzen
+            //file assoc prüfen und in einstellungen richtig setzen
+            if(FileAssociation.Check("Image_Sorter_JPG", Application.ExecutablePath, "JPG Bild", $@"{Application.StartupPath}\AssocIcons\jpg.ico") && 
+                FileAssociation.Check("Image_Sorter_PNG", Application.ExecutablePath, "PNG Bild", $@"{Application.StartupPath}\AssocIcons\png.ico") &&
+                FileAssociation.Check("Image_Sorter_GIF", Application.ExecutablePath, "GIF Bild", $@"{Application.StartupPath}\AssocIcons\gif.ico") &&
+                FileAssociation.Check("Image_Sorter_JPEG", Application.ExecutablePath, "JPEG Bild", $@"{Application.StartupPath}\AssocIcons\jpeg.ico") &&
+                FileAssociation.Check("Image_Sorter_BMP", Application.ExecutablePath, "BMP Bild", $@"{Application.StartupPath}\AssocIcons\bmp.ico") &&
+                FileAssociation.Check("Image_Sorter_TIF", Application.ExecutablePath, "TIF Bild", $@"{Application.StartupPath}\AssocIcons\tif.ico") &&
+                FileAssociation.Check("Image_Sorter_TIFF", Application.ExecutablePath, "TIFF Bild", $@"{Application.StartupPath}\AssocIcons\tiff.ico"))
+            {
+                Properties.Settings.Default.fileAssociation = true;
+            }
+            else
+            {
+                Properties.Settings.Default.fileAssociation = false;
+            }
+            Properties.Settings.Default.Save();
         }
 
         private void Main_Load(object sender, EventArgs e)
@@ -399,13 +414,13 @@ namespace Mk0.Software.ImageSorter
                 if(Directory.Exists($@"{Application.StartupPath}\AssocIcons"))
                 {
                     Directory.Delete($@"{Application.StartupPath}\AssocIcons", true);
-                    FileAssociation.Remove("Image_Sorter_JPG", ".jpg", Application.ExecutablePath, "JPG Bild", $@"{Application.StartupPath}\AssocIcons\jpg.ico");
-                    FileAssociation.Remove("Image_Sorter_PNG", ".png", Application.ExecutablePath, "PNG Bild", $@"{Application.StartupPath}\AssocIcons\png.ico");
-                    FileAssociation.Remove("Image_Sorter_GIF", ".gif", Application.ExecutablePath, "GIF Bild", $@"{Application.StartupPath}\AssocIcons\gif.ico");
-                    FileAssociation.Remove("Image_Sorter_JPEG", ".jpeg", Application.ExecutablePath, "JPEG Bild", $@"{Application.StartupPath}\AssocIcons\jpeg.ico");
-                    FileAssociation.Remove("Image_Sorter_BMP", ".bmp", Application.ExecutablePath, "BMP Bild", $@"{Application.StartupPath}\AssocIcons\bmp.ico");
-                    FileAssociation.Remove("Image_Sorter_TIF", ".tif", Application.ExecutablePath, "TIF Bild", $@"{Application.StartupPath}\AssocIcons\tif.ico");
-                    FileAssociation.Remove("Image_Sorter_TIFF", ".tiff", Application.ExecutablePath, "TIFF Bild", $@"{Application.StartupPath}\AssocIcons\tiff.ico");
+                    FileAssociation.Remove("Image_Sorter_JPG");
+                    FileAssociation.Remove("Image_Sorter_PNG");
+                    FileAssociation.Remove("Image_Sorter_GIF");
+                    FileAssociation.Remove("Image_Sorter_JPEG");
+                    FileAssociation.Remove("Image_Sorter_BMP");
+                    FileAssociation.Remove("Image_Sorter_TIF");
+                    FileAssociation.Remove("Image_Sorter_TIFF");
                 }
             }