Image does not refresh in custom picture box

My custom picture box contains a scrollviewer and an image. A dependecy property Image of type string is used to set the image. ``` public static DependencyProperty ImageProperty = DependencyProperty.Register( "Image", typeof(string), typeof(CustomPictureBox), new FrameworkPropertyMetadata("", new PropertyChangedCallback(OnImageChanged))); private static void OnImageChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { CustomPictureBox cpb = (CustomPictureBox)d; if (e.Property == ImageProperty) { string newvalue = e.NewValue as string; if (!(string.IsNullOrEmpty(newvalue))) { var bmp = new BitmapImage(); bmp.BeginInit(); bmp.UriSource = new Uri(newvalue); bmp.CacheOption = BitmapCacheOption.OnLoad; bmp.EndInit(); cpb.imgPicture.Source = bmp; } else cpb.imgPicture.Source = null; } } ``` An image is acquired via frame grabber and stored to a given location with name "camera_image.tif". The Image property is set to this filename. When I start a new image acquisition, I set the Image property via binding to null and the picture box updates to show no image. When the image acquisition is done, I set it to the "camera_image.tif" again. The problem is that the new image never shows up. Instead it is always the first acquired image that is displayed within the picture box. When I check the image file, it contains the new content. How could I get the picture box to refresh the image? Regards, tabina