What are the properties of Red/Green/Blue that make them the primary colors for light? Are they the only set of three colors that could combine to make all other colors?

Question

And I have the same question for pigment primary colors (magenta/cyan/yellow).

In: Physics

Answer 1

Yes, these are the primary colors of light, **for human eyes**. While the electromagnetic spectrum is continuous, and the eye sees color in a narrow spectrum, and there are relationships between the color sensing cells inside the eye. These cells allow the eye to sense a specific color space, the [CIE 1931 space](https://en.wikipedia.org/wiki/CIE_1931_color_space#CIE_xy_chromaticity_diagram_and_the_CIE_xyY_color_space ). This chromaticity diagram shows the relationship between color frequency and the eye’s perception of it. You could use many colors, but due to the shape of the space you can cover most of it with combinations only three colors if those colors are red, green, and blue. You can use other colors of light, and cover other parts of the space, but red, yellow, and blue only covers the lower right half of the space, so it’s not as good as red green and blue.