title: Detect Alpha Channel with ImageMagick
body: <h3>Scenario</h3>
  <p>I would like to save images with alpha transparency as <code>.png</code> and images without alpha transparency as <code>.jpg</code> (even if their original format is <code>.png</code> or <code>.gif</code>).  How can I detect whether or not an image has alpha transparency using ImageMagick?</p>