Opponent Process

The opponent-process colour theory inspired this diptych. In short, the opponent-process theory of colour suggests that three receptor complexes with opposing actions control our ability to perceive colour. These three receptor complexes are the red-green complex, the blue-yellow complex, and the black-white complex.

For example, while we often see greenish-blue or blueish-reds, we do not see reddish-green or yellowish-blue. Opponent process theory suggests that colour perception is controlled by the activity of two opponent systems: a blue-yellow mechanism and a red-green mechanism.