I'm looking for a way to add blood to an actors face in post (i didn't have time when originally shooting). I'm a relative novice with after effects so i thought i would turn to you guys. I'm a mac user and my editing system is Final Cut Pro.
First thing to do is to track the face- if there's no 3d movement, or very little of it, Mocha should do it. If not, use Syntheyes or Boujou.
Then paint out blood on the face on a relevant frame in Photoshop, animate if necessary and apply track data to layer. Final step is to apply color correction to make it blend in.