posterise

verb3

1. •
   To inadvertently or intentionally reduce the number of colours in (a photograph or other image), changing a continuous gradation of tone to several regions of fewer tones with abrupt changes from one tone to another.
2. •
   To inadvertently or intentionally reduce the number of colours in a photograph or other image, changing a continuous gradation of tone to several regions of fewer tones with abrupt changes from one tone to another.
3. •
   (US, slang) To score a slam dunk in basketball against (one or more opposing players) by leaping over them; also (by extension, sports, slang), to score a goal, a point, etc., in some other sport against (one or more opposing players) in a spectacular manner.