Color and Eye Recognition
Visible light has various colors. Light has a different color depending on the wavelength (or frequency).
So, how do people perceive color? Cone cells in the eye's retina recognize color. There are three kinds of cone cells. Cone cells recognize red, green, and blue light, respectively.
If two or more cells react simultaneously, we recognize another color. The synthesis of light is done in the brain. In fact, you can create full colors by combining red, green, and blue light. TV and monitor screens use this principle.
For example, if you zoom in monitor screen, you can see red, green, and blue pixels. When all three pixels are emitting light, they are seen as white. Also, when red and green are emitted at the same time, we recognize it as yellow.