title: Gaussian blur leads to white frame around image
body: <p>I'm applying a blur effect to an image in WPF like so:</p>
  
  <pre class="lang-xml prettyprint-override"><code>&lt;Image ClipToBounds="True"&gt;
      &lt;Image.Effect&gt;
          &lt;BlurEffect Radius="100" KernelType="Gaussian" RenderingBias="Performance" /&gt;
      &lt;/Image.Effect&gt;
  &lt;/Image&gt;
  </code></pre>
  
  <p>As you can see, the radius is large, because the image is large and I need it to be <em>really</em> blurry. However, for a radius that large I'm getting a light frame around my image as seen in the attached image. How can I suppress this?</p>
  
  <p>In case you're wondering: The result is the same not matter the <code>RenderingBias</code>. A border is also produced in quality-mode.</p>
  
  <p><img src="https://i.stack.imgur.com/5LDP5.png" alt="White border around image"></p>