title: Overlay data onto background image
body: <p>I recently figured out how easy it was to use a background image and map data on top of it using Tableau Public.  Here is the process from their <a href="http://www.tableausoftware.com/support/knowledge-base/background-image-coordinates" rel="noreferrer">website</a>.  As you can see, it is fairly straightforward, and you simply tell the software what image you want to use and how to define the coordinates.</p>
  
  <p>Is the process as straightforward in R?  What would be the best approach?</p>