Can I invert my Mac screen colors without affecting an ext display? I want to connect an external display to my MBPro running 10.11.2 for hosting karaoke. 

I want to invert my Mac display without inverting the external display. I had planned to avoid video mirroring and drag the video window to the external display, but I'm told that won't do the trick.
In Display Settings inside System Preferences different color schemes or filters can be applied to each display. Try applying a regular filter to the external display and invert colors filter on the main display. If you have any other questions feel free to ask!