Green isn't technically a primary color in the traditional sense (red, blue, and yellow for pigment; red, green, and blue for light), but it's treated similarly because our eyes are highly sensitive to it.
Understanding Cone Sensitivity
Our eyes contain cone cells that detect color. There are three types of cone cells, each most sensitive to different wavelengths of light: short (S), medium (M), and long (L).
- Long (L) cones: Peak sensitivity in the greenish-yellow region.
- Medium (M) cones: Highly sensitive to green.
- Short (S) cones: Also sensitive to green, although less so than L and M cones.
This high sensitivity to green wavelengths explains why green plays a significant role in color perception and display technologies. Our visual system readily processes and differentiates shades of green, making it crucial for representing a wide range of colors.
Green in Color Systems
While red, blue, and yellow are historically taught as primary colors in pigment mixing, the additive color system used in screens and displays uses red, green, and blue (RGB). This is because these three colors, when combined in different proportions, can create a vast spectrum of colors. Green is fundamental in this system.
Implications for Color Display
The statement referencing "four colors displayed" suggests a context where maximizing color differentiation is important. Due to our heightened sensitivity to green, it's often chosen as a fourth color to expand the color gamut and improve the overall visual experience.
In Summary
The reason green is often treated like a primary color stems from the fact that our eyes are exceptionally sensitive to it. This sensitivity is due to the overlapping spectral sensitivities of the three types of cone cells in our eyes, particularly the L and M cones. This makes green a crucial component in color perception and display technologies.
