A long time ago I blogged about converting byte arrays to images in XAML applications. I was recently faced with the same problem in WinRT / Windows Store Applications.  The converter code I had before did not work for one simple reason.  Pretty much all IO operations in WinRT are asynchronous, which includes writing to memory streams.  As a result, I had to re-write that code.  I wrote it as an async extension method on byte array, making it easier to consume from calling code.  You can see the code below.

    public static class ByteArrayExtensions
    {
        public static async Task<BitmapImage> AsBitmapImageAsync(this byte[] byteArray)
        {
            if (byteArray != null)
            {
                using (var stream = new InMemoryRandomAccessStream())
                {
                    await stream.WriteAsync(byteArray.AsBuffer());
                    var image = new BitmapImage();
                    stream.Seek(0);
                    image.SetSource(stream);
                    return image;
                }
            }
            return null;
        }
    }

The method returns Task<BitmapImage>.  The reason it returns a Task is because you will be able to call it using await operator.  It returns BitmapImage because it can be directly bound to Source property of Image control in XAML.

Now, to consume this code I am assuming you already have byte array assigned to a property of an object you will be binding to UI.  I am also adding a property of type BitmapImage to the same object, and I will be binding Image to that property.

        private BitmapImage _image;
        public BitmapImage Image
        {
            get { return _image; }
            set { SetProperty(ref _image, value); }
        }
        

Before I bind the object to the UI, I just need to fill my new property as follows:

public async Task LoadImage()
{
  _currentPerson.Image = await _currentPerson.ImageData.AsBitmapImageAsync();
}

When you call LoadImage, you can just wrap that call inside Try/Catch to make sure your errors are handled.  Make sure you do this, as you never know when you might bet a corrupted image, and then your app will fold without proper error handling.

The last step is bind image to this property in the UI.

<Image 
  Source="{Binding Image}" 
  Height="200" 
  Width="200" 
  Margin="2" " />

That is all there is to it.  I know, converter code is easier, but this works very well.

Thanks.