title: Read/save image from/to file in R
body: <p>I need to read an image from a file, do some basic operations pixel-wise and then be able to save it to a file.</p>
  
  <p>I read about the <code>png</code> library and other similar ones, but they don't seem to let you save an image to a file.</p>
  
  <p>My images are currently in GIF format but I wouldn't mind having to convert them to any other conventional format.</p>
  
  <p>Do you know any useful package for this?</p>