All anti-gamma is the same.

Color_Math:Pow node
Value_1 = your incoming color, or white and connected to your incoming color
Value_2 = white - connect to 2.2.

NOTE:EDITED CORRECTION I WROTE THE WRONG FACTOR Value_2 should be 2.2

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)