Change text color based on brightness of the covered background area?

Question

I\'ve thought about the following for a while already, so now I want to know your opinions, possible solutions, and so on.

I am looking for a plugin or technique tha

Answer 1

mix-blend-mode does the trick:

header {
  overflow: hidden;
  height: 100vh;
  background: url(https://www.w3schools.com/html/pic_mountain.jpg) 50%/cover;
}

h2 {
  color: white;
  font: 900 35vmin/50vh arial;
  text-align: center;
  mix-blend-mode: difference;
  filter: drop-shadow(0.05em 0.05em orange);
}

  
Edit me here

Addition (March 2018): Following, a nice tutorial explaining all different types of modes/implementations: https://css-tricks.com/css-techniques-and-effects-for-knockout-text/