Color vision.

Color vision has been studied for centuries, but many fundamental questions remain about the nature of color perception and its neural underpinnings. Typical human color vision is trichromatic - based on three types of cone receptors - yet manifests in a wide variety of individual variations. Similarly, the processing of the cone signals depends on opponent mechanisms that compare the signals from different cone classes. However, the types of comparisons and how they ultimately relate to color appearance or different perceptual tasks are still shrouded in mystery. This review focuses on the processing of color in the retina within the context of the broader goals of color perception and highlights recent insights and questions.