Additive color

[1] Modern formulations of Grassmann's laws[2] describe the additivity in the color perception of light mixtures in terms of algebraic equations.

Additive color predicts perception and not any sort of change in the photons of light themselves.

Examination with a sufficiently powerful magnifying lens will reveal that each pixel in CRT, LCD, and most other types of color video displays is composed of red, green, and blue light-emitting phosphors which appear as a variety of single colors when viewed from a normal distance.

Instead, subtractive color is used to model the appearance of pigments or dyes, such as those in paints and inks.

For his experimental work on the subject, James Clerk Maxwell is sometimes credited as being the father of additive color.

Red, green, and blue lights combining by reflecting from a white wall: secondary colors yellow, cyan, and magenta are found at the intersections of red and green, green and blue, and blue and red. The intersection of all three primary colors together yields white.
James Clerk Maxwell , with his color top that he used for investigation of color vision and additive color
The first permanent color photograph, taken by Thomas Sutton, under the direction of James Clerk Maxwell in 1861
Additive color mixing with CD covers