Working example for WriteableBitmap extensions, grayscale?

May 1, 2013 at 5:30 AM
In the release notes, I see:
WriteableBitmap extensions - darken, grayscale
I downloaded the solution and ran "WinRTXamlToolkit.Sample" to see if I could figure out how to use the WriteableBitmapRenderExtensions(). Unfortantely, when I try to use WriteableBitmapRenderTestPage.xaml, the app crashes on line 37 of the code-behind:
            wb = await WriteableBitmapRenderExtensions.Render(this.source);
With the exception:
System.NotSupportedException was unhandled by user code
  HResult=-2146233067
  Message=Unable to expand length of this stream beyond its capacity.
  Source=mscorlib
  StackTrace:
       at System.IO.UnmanagedMemoryStream.Write(Byte[] buffer, Int32 offset, Int32 count)
       at WinRTXamlToolkit.Composition.CompositionEngine.<RenderToWriteableBitmap>d__0.MoveNext() in d:\ehunatfs\ehuna2\Nds\Sandbox\WinRTXamlToolkit\WinRTXamlToolkit.Composition\CompositionEngine.cs:line 131
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
       at WinRTXamlToolkit.Composition.WriteableBitmapRenderExtensions.<Render>d__0.MoveNext() in d:\ehunatfs\ehuna2\Nds\Sandbox\WinRTXamlToolkit\WinRTXamlToolkit.Composition\WriteableBitmapRenderExtensions.cs:line 31
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
       at WinRTXamlToolkit.Sample.Views.WriteableBitmapRenderTestPage.<RunTest>d__0.MoveNext() in d:\ehunatfs\ehuna2\Nds\Sandbox\WinRTXamlToolkit\WinRTXamlToolkit.Sample\Views\Imaging\WriteableBitmapRenderTestPage.xaml.cs:line 37
  InnerException: 
Does anyone have an example on how to transform a Bitmap to grayscale?