Human vision allows us to perceive and distinguish various wavelengths of light, which we perceive as different colors. However, our eyes are designed to detect a range of wavelengths simultaneously rather than perceiving individual wavelengths in isolation.
The human eye contains cells called photoreceptors, specifically cones and rods, located in the retina. Cones are responsible for color vision and function best in well-lit conditions, while rods are more sensitive to low light levels and primarily contribute to black and white vision.
Within the cones, there are three types of photoreceptor cells that are sensitive to different ranges of wavelengths: short-wavelength cones (also known as S-cones) that are most sensitive to shorter wavelengths (around 420-440 nanometers) and perceive blue light, medium-wavelength cones (M-cones) sensitive to middle wavelengths (around 530-540 nanometers) and perceive green light, and long-wavelength cones (L-cones) sensitive to longer wavelengths (around 560-580 nanometers) and perceive red light.
When light enters the eye, it stimulates these different types of cones to varying degrees depending on its wavelength composition. The combined response of these cones enables us to perceive a wide range of colors. For instance, when light predominantly stimulates the L-cones, we perceive the color red, and when the M-cones are predominantly stimulated, we perceive green.
Therefore, our perception of color arises from the relative activation of these different cones in response to the various wavelengths of light present in our environment. The brain processes this information to create our experience of seeing different colors. It is the simultaneous stimulation of multiple cones across the visible spectrum that allows us to perceive a broad range of colors and not just individual wavelengths.