Posterising

Part of speech: verb

Definitions

1. Converting a photograph or picture into flat areas of a few distinct tones ; giving an image a bold, graphic look like a printed poster
2. Reducing the smooth gradations of tone in an image so it shows only a few flat shades ; making a picture or design look like a bold printed poster
3. Breaking the continuous shading of a picture into a handful of solid tones ; rendering a visual subject in the flat, vivid style of a poster

Etymology: Posterising is the present participle of a verb built from "poster" and the verbal suffix "-ise", so the story is mostly the story of the noun it grows from. "Poster" comes from Middle English "poster", a borrowing of Old French "poste", ultimately from Latin "postis", meaning a doorpost or post. Its link to paper is a later extension: a bill or notice was fixed to a post or wall, and the object came to be named for the place where it hung. The verb is much more recent. It is formed in English from "poster" plus "-ise", the suffix that reached English through Middle French and Late Latin from Ancient Greek "-izein". To poster something is to reduce an image to flat blocks of tone, giving it the bold, graphic look of a printed poster. The verb's formation is a plain English compound of noun and suffix, with no separate older history behind it.