Did Young Helmholtz describe the Trichromatic theory or Opponent Color theory of color vision?

The Trichromatic theory, also known as the Young-Helmholtz theory, was developed by Thomas Young and later expanded upon by Hermann von Helmholtz. This theory posits that there are three types of color receptors in the eye, corresponding to the primary colors of light: red, green, and blue. According to this theory, different colors are perceived as a result of the combinations and proportions of stimulation of these three types of receptors. For instance, when light stimulates both red and green receptors, a person perceives yellow.

In contrast, the Opponent Color theory, introduced by Ewald Hering, describes color perception in terms of opposing pairs: red-green, blue-yellow, and black-white. This theory focuses on how the visual system processes color information via these opposing channels, explaining phenomena such as afterimages and color blindness that the Trichromatic theory does not fully account for.

Thus, the correct answer recognizes that Young and Helmholtz specifically contributed to the Trichromatic theory of color vision, rather than the Opponent Color theory.