title: RenderedImage -> RGB values
body: <p>I use an interface of RenderedImage for reading a tif image.
  How can I get all rgb values of this picture in a 2d-Array like this:</p>
  
  <pre><code>red[0][128] = 120; // means x=0, y=128, red value = 120
  // the value 120 is the value I have to determine (and oall other rgb values)!
  </code></pre>
  
  <p>Does anyone know this?</p>
  
  <p>Thanks a lot for your help!</p>