title: Please explain this color blending mode formula so I can replicate it in PHP/ImageMagick
body: <p>I've been trying to use ImageMagick to replicate Photoshops Colour Blend Mode. I found the following formulas in an <a href="http://www.simplefilter.de/en/basics/mixmods.html" rel="nofollow noreferrer">online guide</a> but I don't know what they mean. Do I just need to swap certain channels?</p>
  
  <p><img src="https://i.stack.imgur.com/uyUM6.gif" alt="Paint Shop Pro"></p>
  
  <p><img src="https://i.stack.imgur.com/V7wrx.gif" alt="farbe"></p>