There are two types of color models – additive and subtractive. Today we will explain additive color mixing, also known as an additive color model.
The human eye mixes the three RGB additive primary colors – red, green, and blue – in various combinations and intensities to simulate the full range of colors in nature. Reflected light that contains a mix of pure red, green, and blue is perceived as white. When no light is present, we perceive black. This is the basis of the RGB color model.
Additive Color Models – Input and Output
RGB is an additive color mixing process where various wavelengths of light combine to form white light.
Input and output devices that leverage RGB start with darkness and add red, green, and blue light beams over a black surface or screen to create color. RGB input devices include digital cameras and scanners. RGB output devices include TVs and computer monitors. Of course, some devices like smart phones and tablets can be both RGB input and output devices.
Additive Color Mixing Process
RGB devices start with darkness and add red, green, and blue light beams over a black surface or screen to create color. Each of these beams has a level of intensity, from fully on to fully off. These red, green, and blue beams superimpose in various intensities to create a spectrum of color.
The color we perceive is determined by the intensity of each beam. For example, if each beam has zero intensity, meaning no light, the screen will appear black. If each beam has full intensity, the screen will appear white. If all three beams have the same intensity, the color will appear gray.
We see color based on the intensity of each beam. If the red beam is strongest, we will see red. If the red and blue beams are equal intensity and the green beam is low, we will see magenta. This secondary color is achieved by mixing the two primary colors, red and blue.
The color rendering methods used by these devices are based directly on our response to stimuli of red, green, and blue light. Like the human eye, these devices must also process a large amount of color information at once—on screen. In logical fashion, these devices imitate the eye’s response to the additive primaries to create a colorful illusion.
For example, a computer monitor blends varying intensities of red, green, and blue light at each of its tiny pixels. These pixels are so small and tightly packed that the eye’s RGB response is “fooled” into the perception of many different colors when really there are only three.