Opponent process theory

Opponent process theory holds that vision encodes color through opposing red–green and blue–yellow channels, alongside a light–dark channel. It explains why certain color pairings resist simultaneous perception and how afterimages arise.

Retinal ganglion cell: A retinal neuron that sends visual signals toward the brain and can respond antagonistically to different parts of its receptive field. Some retinal ganglion cells show the antagonistic responses that support opponent coding.
Ewald Hering: A nineteenth-century German physiologist who developed a theory of color vision based on opposing processes. Hering proposed the red–green and blue–yellow oppositions that define this theory.
Color vision: The visual capacity to discriminate wavelengths and perceive colors. Opponent process theory is one account of how color vision organizes its signals.
Retinex theory: A theory of color vision that explains perceived surface color through comparisons across the visual scene. It addresses color constancy at a broader scene level than opponent-channel coding alone.
Lateral geniculate nucleus: A thalamic structure that relays and organizes visual signals from the retina to the cerebral cortex. Its color-sensitive neurons carry opponent responses onward from the retina.
Young–Helmholtz theory: A theory that explains color vision through three types of cone receptors with different spectral sensitivities. Its three-receptor account initially appeared to conflict with Hering's opponent channels.
Cone cell: A retinal photoreceptor specialized for vision in brighter conditions and for distinguishing wavelengths. Opponent channels are built from signals originating in cone cells.
Additive color: Color produced by combining emitted lights, typically red, green, and blue primaries. Light mixtures can combine red and green even though opponent coding treats them as opposing signals.
Color afterimage: A perceived color that appears after prolonged viewing of a differently colored stimulus. Opponent-channel adaptation helps explain why a fatigued channel produces a complementary afterimage.
Thomas Young: An English polymath whose work proposed that color vision depends on three kinds of receptors. Young's proposal became a foundation for the theory Hering opposed.

Linked from 23 pages