title: C# Removing transparancy from BitmapImage
body: <p>i'm using a .png as a BitmapImage. The image is being used as a texture on a 3d model.
  There is some transparancy in the image which i want to remove.
  How do i remove it? (as efficiently as possible, using VisualBrush or System.Drawing.Image is not an option.)</p>
  
  <pre><code>    BitmapImage bi = new BitmapImage();
      bi.BeginInit();
      bi.UriSource = new Uri(fullPath, UriKind.Absolute);
      bi.EndInit();
      bi.Freeze();
      ImageBrush br = new ImageBrush(bi) { Stretch = Stretch.Fill };
      DiffuseMaterial mat = new DiffuseMaterial(br);
  </code></pre>