[pachydermic]

It's not. That's an "enhanced" color picture, meaning the colors you see include information from stuff like infrared images and whatnot. Maybe the contrast has been increased, or colors added to make certain features visible. Well, certainly a lot of work has been done to that image as the article suggests. Not surprising considering the extreme conditions the photograph was taken in (the speed of New Horizons, the light available, the instruments used, the fact that the data has to be sent over such a long distance, etc).