title: Ruby Rmagick: Crop/"Trim" excessive (white) space of image automatically
body: <p>I'm taking a "Screenshot" of HTML documents with IMGkit (<a href="https://github.com/csquared/IMGKit" rel="nofollow">https://github.com/csquared/IMGKit</a>).
  The background is <em>always</em> white (#ffffff).</p>
  
  <p>IMGkit is taking 1200 x 1000 pixel big "Screenshots", and I might end up with a lot of white space as the actual content of the HTML documents may be very small.</p>
  
  <p>Are there built in functions in Rmagick to crop/trim this excessive white space automatically?</p>