Unlike the older MacBook’s which used LVDS signaling the newer retina systems use iDP signaling which is a very different signaling system. So the symptoms of colored bands and screens for a bad cable don’t show up here. This system is either a bad driver within the display or the logic board’s GPU logic.
What happens when you use an external display does the external exhibit the same behavior? If it does then the GPU logic needs to be looked into (likely needing a new logic board). If on the other hand the external display looks OK and the internal shows the bad image then it’s within the display and would need a new display assembly.