title: how to reduce the quality of pdf created using R
body: <p>I am creating pdf reports using R (command <em>?pdf</em>).
  The reports contain images that I have created and that are quite heavy (lot of datapoints)
  The created pdfs are very heavy. Is there a way to reduce the quality of the pdf when creating it?</p>
  
  <p>I know I can do it using <em>pdftk</em> but I'd rather do it in one go as I want to minimize the number of manual operations.</p>