diff --git a/XplorePlane/Services/ImageConverter.cs b/XplorePlane/Services/ImageConverter.cs
index 1e22b09..416e1e1 100644
--- a/XplorePlane/Services/ImageConverter.cs
+++ b/XplorePlane/Services/ImageConverter.cs
@@ -10,6 +10,19 @@ namespace XplorePlane.Services
 {
     public static class ImageConverter
     {
+        public static byte[] ExtractGray8Pixels(BitmapSource bitmapSource, out int width, out int height)
+        {
+            if (bitmapSource == null) throw new ArgumentNullException(nameof(bitmapSource));
+
+            var formatted = new FormatConvertedBitmap(bitmapSource, PixelFormats.Gray8, null, 0);
+            width = formatted.PixelWidth;
+            height = formatted.PixelHeight;
+            int stride = width;
+            byte[] pixels = new byte[height * stride];
+            formatted.CopyPixels(pixels, stride, 0);
+            return pixels;
+        }
+
         public static Image<Gray, byte> ToEmguCV(BitmapSource bitmapSource)
         {
             if (bitmapSource == null) throw new ArgumentNullException(nameof(bitmapSource));
@@ -26,6 +39,13 @@ namespace XplorePlane.Services
             return image;
         }
 
+        public static Image<Gray, byte> ToEmguCVFromPixels(byte[] pixels, int width, int height)
+        {
+            var image = new Image<Gray, byte>(width, height);
+            image.Bytes = pixels;
+            return image;
+        }
+
         public static BitmapSource ToBitmapSource(Image<Gray, byte> emguImage)
         {
             if (emguImage == null) throw new ArgumentNullException(nameof(emguImage));
diff --git a/XplorePlane/Services/ImageProcessingService.cs b/XplorePlane/Services/ImageProcessingService.cs
index c7f2799..18bba8d 100644
--- a/XplorePlane/Services/ImageProcessingService.cs
+++ b/XplorePlane/Services/ImageProcessingService.cs
@@ -99,13 +99,16 @@ namespace XplorePlane.Services
             if (!_processorRegistry.TryGetValue(processorName, out var processor))
                 throw new ArgumentException($"Processor not registered: {processorName}", nameof(processorName));
 
+            // Extract pixels on the UI thread (BitmapSource / FormatConvertedBitmap are DependencyObjects)
+            var rawPixels = ImageConverter.ExtractGray8Pixels(source, out int imgWidth, out int imgHeight);
+
             return await Task.Run(() =>
             {
                 cancellationToken.ThrowIfCancellationRequested();
 
                 try
                 {
-                    var emguImage = ImageConverter.ToEmguCV(source);
+                    var emguImage = ImageConverter.ToEmguCVFromPixels(rawPixels, imgWidth, imgHeight);
 
                     if (parameters != null)
                     {
@@ -118,6 +121,7 @@ namespace XplorePlane.Services
                     progress?.Report(0.9);
 
                     var result = ImageConverter.ToBitmapSource(processedEmgu);
+                    result.Freeze(); // must freeze before crossing thread boundary
                     progress?.Report(1.0);
 
                     return result;
diff --git a/XplorePlane/ViewModels/ImageProcessingViewModel.cs b/XplorePlane/ViewModels/ImageProcessingViewModel.cs
index 1a4078d..09722b8 100644
--- a/XplorePlane/ViewModels/ImageProcessingViewModel.cs
+++ b/XplorePlane/ViewModels/ImageProcessingViewModel.cs
@@ -111,7 +111,6 @@ namespace XplorePlane.ViewModels
 
             try
             {
-                SelectedProcessor = processorName;
                 var parameters = _imageProcessingService.GetProcessorParameters(processorName);
                 CurrentParameters.Clear();
                 foreach (var param in parameters)