title: PHP Imagick transparency issue with PNG
body: <p>I am using imagemagick 6.8.4-6 and i'm having an issue with setting the PNG on rotate to have a transparent background. My code is below and i am using imagick through php</p>
  
  <pre><code>$base = new Imagick("images/Champs-43.png"); 
  $layer = new Imagick("images/coporate1.png");
  $base-&gt;setFormat("png32");
  $layer-&gt;setFormat("png32");
  $layer-&gt;rotateImage(new ImagickPixel("none"), 45);
  
  $base-&gt;compositeImage($layer, imagick::COMPOSITE_DEFAULT, 20, 20);
  header('Content-Type: image/png');
  echo $base;
  </code></pre>
  
  <p>the above gives a black background to the area rotated. i have tried "none", "transparent", "#00000000", and "rgba(0, 0, 0, 0.0)" and none of them seem to work.</p>
  
  <p>Any help appreciated</p>