title: Convert negative image to positive
body: <p>I have old negative films I have scanned onto my computer. I want to write a small program to convert the negative Images to its positive state.</p>
  
  <p>I know there are several image editor applications out there which I can use to achieve this conversion, but I am researching on how to manipulate the pixels to convert them myself via a small app.</p>
  
  <p>Can anyone give me a head start on this? Sample code if possible will also be much appreciated.</p>