title: Can I swap colors in image using GD library in PHP?
body: <p>I got the image like this (it's a graph):</p>
  
  <p><a href="https://i.stack.imgur.com/vyayH.gif" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/vyayH.gif" alt="Gold Trade Graph"></a><br>
  <sub>(source: <a href="http://www.kitconet.com/charts/metals/platinum/tny_pt_en_caoz_2.gif" rel="nofollow noreferrer">kitconet.com</a>)</sub>  </p>
  
  <p>I want to change the colours, so the white is black, the graph line is light blue, etc.. is it possible to achieve with GD and PHP?</p>