title: Fullscreen image
body: <p>Im developing on WP8... I want to render an image in fullscreen size... obviously i do not the size of the screen...
  I try to explain another problem... I must resize the image (image are about 2000x1400px and the screen is about 800x4450px).. but i dont really want to resize the real dimension... i just want the dimension remain the same but i want to see the full image (no cutted)</p>
  
  <p>Here the code i have written</p>
  
  <pre><code>System.Windows.Size dimensions = App.RootFrame.RenderSize;
  
  WriteableBitmap wb = new WriteableBitmap((int)dimensions.Width,(int)dimensions.Height);
  wb.LoadJpeg(myStreamPhoto);
  wb.Invalidate();
  
  ImgChosenPhoto.Source = wb; 
  </code></pre>
  
  <p>I achieve the goal in this way... the image is not really resized but, however, i can see the full image on screen.. so what's the problem?</p>
  
  <p>If I open the image directly from my app everything works! If i open the photo from the photo library and select my app i obtain an exception (same code is runned).. the exception is: </p>
  
  <pre><code>Value does not fall within the expected range.
  </code></pre>