The capacity to perceive and differentiate various components of the color spectrum relies on the human ability to perceive electromagnetic radiation, characterized by a range of wavelengths spanning approximately 400 to 700 nanometers (millionths of a millimeter). Distinct wavelengths elicit nerve signals within the retina, the light-sensitive layer of cells located at the rear of the eye. These signals are subsequently transmitted to the brain and interpreted as the colors violet, indigo, blue, green, yellow, orange, and red.
When light reaches the retina, it interacts with specialized light-sensitive cells known as rods and cones. Rods have the ability to detect all visible light, whereas cones are responsible for discerning colors. The cones can be categorized into three types: red-sensitive, blue-sensitive, and green-sensitive. Each type of cone exhibits heightened sensitivity to a specific portion of the light spectrum. The cones are predominantly concentrated in a central region of the retina called the fovea. Consequently, the perception of colors is most precise when directly viewing objects, as the fovea plays a crucial role in color vision. Conversely, color vision tends to be less accurate in the peripheral areas of vision.
When light stimulates a cone, it induces a structural alteration in the pigment present within the cone, leading to the generation of an electrical signal. This signal is then transmitted to the brain through the optic nerve. The perception of color necessitates a minimum level of light. Below this threshold, visual information is solely processed by the rods and is perceived as different shades of grey.