XAML image quality (interpolation) in the Metro-Style app

Given the following image object (it is in the DataTemplate of the ListView object):

  <Image Source="{Binding ImgSource}" ImageOpened="img_ImageOpened" />

How should I get a high-quality bicubic interpolated image? (on screen, the size of this image is smaller than the original PNG, but the default resizing is apparently done using poor-quality "nearest neighbor" interpolation).

Since I would like to rely only on data binding (whenever the ImgSource of the associated data item changes, the contents of the image should change), I tried to install the ImageOpened handler and change the image just loaded for the better - quality.

Unfortunately, the code below seems to be inoperable (I just get blank images):

    async void LoadImage(Image imgControl, string source)
    {
        try
        {
            StorageFile file = await StorageFile.GetFileFromPathAsync(source);

            IRandomAccessStream fileStream = await file.OpenAsync(FileAccessMode.Read);
            BitmapDecoder decoder = await BitmapDecoder.CreateAsync(fileStream);

            InMemoryRandomAccessStream ras = new InMemoryRandomAccessStream();
            BitmapEncoder enc = await BitmapEncoder.CreateForTranscodingAsync(ras, decoder);

            enc.BitmapTransform.InterpolationMode = BitmapInterpolationMode.Cubic;
            enc.BitmapTransform.ScaledHeight = Convert.ToUInt32(imgControl.ActualHeight);
            enc.BitmapTransform.ScaledWidth = Convert.ToUInt32(imgControl.ActualWidth);

            await enc.FlushAsync();

            Windows.UI.Xaml.Media.Imaging.BitmapImage bImg = new Windows.UI.Xaml.Media.Imaging.BitmapImage();
            bImg.SetSource(ras);
            imgControl.Source = bImg;
        }
        catch (Exception e)
        {
            return;
        }
    }

    void img_ImageOpened(object sender, RoutedEventArgs e)
    {
        Image imgControl = (Image)sender;
        LoadImage(imgControl, <path to PNG file>);
    }