title: How do I make a png with transparency appear transparent in MatLab?
body: <p>I have an image with a transparent background, but when I open it in MATLAB, I get a black background.  I'm overlaying it on top of a background image. How can I get this to display? I've tried using the alpha function <code>alpha(image,0)</code> but it sets my entire image to 0.  Is it possible for me to set the alpha of individual pixels to be equal to 0?  That way I can run each pixel through a loop.</p>
  
  <p>I'm not sure if this helps, but when I run a <code>imfinfo('ryu1.png')</code>, I get :</p>
  
  <pre><code>...
  Transparency = 'alpha' 
  SimpleTransparencyData = []
  ...
  </code></pre>