Chromatacia is the world that the Shades of Grey series is set in. It is a dystopian universe where people are judged by what colour they can see, as each person can only see a maximum of two colours and many can see none. So far Jasper Fforde has only written one book in this series, Shades of Grey, but he has plans to write two more.
People who can see red and blue, or "Purples" are the highest, followed by those who can only see blue - "Blues", and so on down to those who can only see red - "Reds". The people who can only see in monochrome with no colour whatsoever are "Greys" and at the very bottom of the hierarchy. People on opposite sides of the colour spectrum - for example Reds and Greens - are not allowed to be friends, and generally have a deep rivalry.
It is possibly the same world that we live in, only many years later, after the "Something that Happened".