title: Creating multiple thumbnails in ImageMagick / GraphicsMagick
body: <p>I'm currently writing a shellscript for Bash, that will create different size thumbnails for some rather massive amounts of large images.</p>
  
  <p>I was wondering if it's possible to get GM/IM to create multiple sizes of thumbs in one run, to avoid loading the same image over and over again to create different thumbnails, thus saving memory and time in executing the script ?</p>