title: ImageMagick: How to resize proportionally with mogrify without a background
body: <p>I was following this example <a href="http://cubiq.org/create-fixed-size-thumbnails-with-imagemagick">http://cubiq.org/create-fixed-size-thumbnails-with-imagemagick</a>, and it's exactly what I want to do with the image, with the exception of having the background leftovers (i.e. the white borders). Is there a way to do this, and possibly crop the white background out? Is there another way to do this? The re-size needs to be proportional, so I don't just want to set a width re-size limit or height limit, but proportionally re-size the image.</p>