title: Image Magick: convert and composite in one command
body: <p>I am currently working on a automation script to convert imgaes for use on websites. Every image gets a white and black border and is combined with a prepared alpha channel image. The black border (outer border) combined with the alpha channel will look like a shadow when everything is done.</p>
  
  <p>I've got the following files:</p>
  
  <ul>
  <li>test.jpg (the test image)</li>
  <li>test.tga (the alpha channel)</li>
  </ul>
  
  <p>And I convert the input image in 2 steps:<br>
  <code>convert test.jpg -bordercolor #FFFFFF -border 15 -bordercolor #000000 -border 30 test.png</code><br>
  (adds the white and black border to the image and saves as 'test.png')<br>
  <code>composite -compose CopyOpacity test.tga test.png test2.png</code><br>
  (joins image file with alpha channel from test.tga and saves as test2.png)</p>
  
  <p>So now my question is: Is there any way to invoke both steps as one command? I know that <code>convert</code> also supports the <code>-compose</code> options, if I got that right from the manual, but I could not get it working. It would be best, if I could edit and join the image with the alpha channel with one command. (Command will be executed from my Application and I don't want to execute many sub-processes)</p>
  
  <p>Maybe someone knows a solution for this.
  Thanks in advance!</p>