Posterization takes a smooth gradient and converts it to fewer steps with abrupt changes between them – a staircase kind of effect. This was originally done with photographic processes to make posters, which is where the name of the effect is derived from.
With additions made to the profile curves, Material Mixer, BPR Filters and a new 3D Posterize feature you can now easily create a cell shaded render.
Posterization isn’t only for BPR renders. It can be applied to any profile curve in ZBrush. This means that you can add a posterization effect to a brush curve, a brush alpha or any other place a profile curve is used.
Posterization can also be found in premade settings to make your creative work easier, such as in the render settings or through the BPR filters.