What does the Young-Helmholtz trichromatic theory propose?

The Young-Helmholtz trichromatic theory is a foundational concept in the understanding of color vision. It proposes that the human retina contains three types of color receptors, which are sensitive to different wavelengths of light corresponding to red, green, and blue. This triad of photoreceptors allows us to perceive a wide range of colors through the additive mixing of these three primary colors.

The theory explains that when light of different wavelengths hits these receptors, the brain analyzes the relative activation levels of each type of receptor, which results in our perception of color. For example, if red and green receptors are stimulated, we perceive yellow. This model effectively accounts for a range of color vision phenomena and has been supported by various experimental findings in color science.

Understanding this theory is crucial because it emphasizes the role of the specific types of receptors in color vision, rather than suggesting a more simplistic view of color perception based solely on a limited number of receptors or by brightness alone.