title: Thumbnails in node-gm graphicsmagick without upscaling
body: <p>Hello I want to make thumbnails without upscaling. I use this one code:</p>
  
  <pre><code>gm(__dirname + '/images/Lighthouse.jpg')
  .noProfile()
  .gravity('Center')
  .thumb('1920', '1280&gt;', __dirname + '/images/thumb.jpg', 90, function (err){
      if (err) { console.log(err); }
  });
  </code></pre>
  
  <p>But it still upscale result image. I try another way:</p>
  
  <pre><code>gm(__dirname + '/images/Lighthouse.jpg')
  .noProfile()
  .gravity('Center')
  .resize('1920', '1280' + "&gt;")
  .quality(90)
  .crop('1920', '1280')
  .write(__dirname + '/images/resize.jpg', function (err) {
      if (err) { console.log(err); }
  });
  </code></pre>
  
  <p>It really prevent upsculing, but, i can't pass another option - "^" in resize because without it i get wrong result of thumbnail. You can compare it on:</p>
  
  <pre><code>gm(__dirname + '/images/Lighthouse.jpg')
  .noProfile()
  .gravity('Center')
  .thumb('320', '480', __dirname + '/images/thumb.jpg', 90, function (err){
      if (err) { console.log(err); }
  });
  
  gm(__dirname + '/images/Lighthouse.jpg')
  .noProfile()
  .gravity('Center')
  .resize('320', '480' + "^")
  .quality(90)
  .crop('320', '480')
  .write(__dirname + '/images/resize.jpg', function (err) {
      if (err) { console.log(err); }
  });
  </code></pre>
  
  <p>This code return similar result, but upscale image. Is there any way to provide "^>" options together? Thanks.</p>
  
  <p>P.S. Seems like thumbinal method a little bit blurred than resize/crop.</p>