A Colourcube resource is used by both the EnvironmentSettings and PostFX to change the colour and tone of the world.

The colourcube is a 1024x32 CLUT which is usually colour corrected to give a different art style to the game at a given time (i.e the red filter when wrecking a vehicle in versions 1.0-1.3 of Burnout Paradise)

Some time after the February 22, 2007 build of Paradise, colourcubes were added to the EnvironmentSettings folder and were used specifically to give the game a unique art style.

In the 1.4 update to Burnout Paradise, the colourcube was changed to a standard RGB CLUT, possibly due to the extended timecycle conflicting with the colourcube's art style.

An RGB CLUT, used as a Colourcube in all known versions of Burnout Paradise
An edited CLUT, used as the Colourcube that is applied when you wreck your car