# – Using additive colour theory, red + red + blue = what?

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ELI5

Using the additive colour theory, when I add equal parts of red & blue together it is magenta.

But what happens if I add two parts red & one part blue together? Is it still “pure” magenta? Or has it shifted off to the side of red, a little?

Context: I’m creating a game using additive colour theory and I’m a bit perplexed on this one.

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You seem to be mixing intensity with color. These are different things. When you talk about color, the most you can have is 100%. So 50% red and 50% blue gives magenta. 66% red and 33% blue is a different color, a bright red or pink. This is all discussing the hue dimension. Saturation is a separate dimension, all these colors are fully saturated. If you mix in white, you reduce the saturation, making the colors more pastel.

These is no agreed-to standard set of names for colors. Or, there are many standard sets of names for colors which are all different from each other. Your choice of interpretation.

Intensity is a completely different thing, it’s about how bright the light is, number of photons per second, independent of these color models.

Yes, if you change the proportion, the result will change. Have you never mixed crayons or aquarelle paints? In your example two part red + one part blue will end up being something like (depending on saturation) something like #C80064 (or 200,0,100) in RGB

On the RGB color wheel, the color #FF0080 (i.e. 100% of red pixels lit, 50% of blue pixels lit, and 0% of green pixels lit), is usually called “Rose”.

Obviously if you combine Red and Magenta additively you’ll get a very *bright* Rose. Difficult to represent that on a computer screen, since it has a limit to how bright it can get. If you wanted to be scientifically accurate you’d have to instead show it as Maroon (#800000) + Purple (#800080) = Rose (#FF0080), which probably isn’t very satisfying.