The RGB color model is an additive color model in which red , green , and blue light are added together in various ways to reproduce a broad array of colors . The name of the model comes from the initials of the three additive primary colors , red, green, and blue. The main purpose of the RGB color model is for the sensing, representation, and display of images in electronic systems, such as televisions and computers, though it has also been used in conventional photography .

Before the electronic age, the RGB color model already had a solid theory behind it, based in human perception of colors . ^[1] The CMYK color model (process color, four color) is a subtractive color model , used in color printing , and is also used to describe the printing process itself. CMYK refers to the four inks used in some color printing: cyan , magenta , yellow , and key black . Though it varies by print house, press operator, press manufacturer and press run, ink is typically applied in the order of the abbreviation. The CMYK model works by partially or entirely masking colors on a lighter, usually white, background. The ink reduces the light that would otherwise be reflected. Such a model is called subtractive because inks “subtract” brightness from white. In additive color models such as RGB, white is the “additive” combination of all primary colored lights, while black is the absence of light.