title: Reverse white and black colors in a PDF
body: <p>Given a black and white PDF, how do I reverse the colors such that background is black and everything else is white?</p>
  
  <p>Adobe Reader does it (<em>Preferences -> Accessibility</em>) for viewing purposes only in the program. But does not change the document inherently such that the colors are reversed also in other PDF readers. </p>
  
  <p>How to reverse colors permanently?</p>