What is additive or subtractive color theory?
Color theory refers to the science and art of combining colors. There are two main types of color theory: additive and subtractive. Additive color mixing involves combining light of different colors, while subtractive color mixing involves combining pigments or dyes of different colors. Understanding both theories is important for artists, designers, photographers and others who work with color.
Additive Color Theory
Additive color theory deals with light and how the eye perceives color from different wavelengths of light. The primary colors in additive color theory are red, green and blue (RGB). These are the three main hues detected by the human eye. All other colors are created by mixing varying amounts of these three primary hues.
The RGB Color Model
The RGB color model is based on the additive mixing of red, green and blue light. When red, green and blue light are mixed together in equal amounts, they create white light. The combination of just two primary colors creates secondary colors – yellow (red + green), cyan (green + blue) and magenta (blue + red).
| Primary Colors | Secondary Colors |
|---|---|
| Red | Yellow |
| Green | Cyan |
| Blue | Magenta |
The absence of all three primary colors results in black. By mixing varying intensities of the three primary hues, a wide gamut of colors can be produced. This is the basis for many color mixing applications such as televisions, computer monitors, theater lighting and more.
Additive Color in Action
We can see additive color mixing in action with theater lighting. Using red, green and blue colored stage lights, a lighting designer can create almost any color by adjusting the brightness of each light and overlapping the beams. TV and computer screens also use additive RGB color by having tiny red, green and blue light pixels that emit different amounts of colored light to display images.
Additive color mixing also explains how white light works. Although sunlight appears white or yellow to our eyes, it actually contains a full spectrum of wavelengths from violet to red. When all these wavelengths hit our eyes simultaneously, our visual system perceives them together as white light.
Subtractive Color Theory
While additive color deals with light emission, subtractive color is based on light absorption. Subtractive color mixing involves combining pigments, dyes, inks or natural colorants to create various hues.
The CMY Color Model
The primary colors in subtractive color theory are cyan, magenta and yellow (CMY). These are the complementary colors to the RGB primaries used in additive color. Complementary colors are located opposite each other on the color wheel.
| Additive Primary | Subtractive Primary |
|---|---|
| Red | Cyan |
| Green | Magenta |
| Blue | Yellow |
In subtractive color mixing, each colorant absorbs or “subtracts” certain wavelengths of light while reflecting others. The combination of cyan, magenta and yellow absorbs most visible light, resulting in black:
- Cyan absorbs red light
- Magenta absorbs green light
- Yellow absorbs blue light
Overlapping two primary subtractive colors creates the secondary colors:
| Primary Colors | Secondary Colors |
|---|---|
| Cyan | Blue |
| Magenta | Red |
| Yellow | Green |
Varying combinations of the subtractive primaries can create a wide range of colors.
Subtractive Color in Action
We see subtractive color mixing at work with paints, dyes, inks and natural colorants. For example, mixing blue and yellow paint creates green paint because:
- Blue paint absorbs red and green light
- Yellow paint absorbs blue light
- Together, they absorb red and blue, leaving green
Cyan, magenta, yellow and black (CMYK) inks work via subtractive color to print full color images. Digital printers lay down layers of these inks on paper, absorbing selected wavelengths of light to recreate color images.
Subtractive color also explains how objects have color. A red apple looks red because its skin pigments absorb blue and green light, reflecting only red wavelengths to our eyes. A yellow banana peel absorbs blue light and reflects green and red.
Key Differences Between Additive and Subtractive Color
Although additive and subtractive color mixing both involve primary colors and secondary colors, there are important differences between the two theories:
| Additive Color | Subtractive Color |
|---|---|
| Involves light emission | Involves light absorption |
| RGB are the primary colors | CMY are the primary colors |
| Combining all colors makes white | Combining all colors makes black |
| Used for TV, projectors, etc. | Used for paints, dyes, pigments |
These fundamental differences mean the two color modes are complementary. When working in both modes, understanding their interplay is key. For example, cyan ink absorbs red light, so prints with cyan will look darker where red light shines on them.
Applications of Additive and Subtractive Color
Understanding additive and subtractive color theory has many practical applications across different fields:
Digital Displays
RGB emissive displays like TVs and phones use additive color to create images. Subpixels emit different amounts of red, green and blue light to display color pictures.
Printing
CMYK inks are used in additive color mixing to print color images on paper. The colors and intensity of each ink layer are carefully calculated to absorb the right light wavelengths.
Painting
Painters mix, layer and blend pigments using subtractive color principles to create desired hues. Transparent watercolor relies heavily on subtractive mixing.
Dyeing
Fabric dyers use the subtractive CMY primaries along with other dyes to color textiles. Understanding color absorption allows better color control.
Lighting
Lighting designers skillfully use additive RGB mixing with stage lights to create dramatic color palettes and effects.
Photography
Photographers consider subtractive color and light absorption when choosing filters, gels and other mods to control color. The color balance of photos relies on subtractive theory.
Color Correction
Whether adjusting photos, video or prints, editors use principles of additive and subtractive color to troubleshoot and correct color balance and cast issues.
The Origins of Additive and Subtractive Color Theory
The discovery of additive and subtractive color mixing was an important milestone in the history of color theory. Here are some key figures and events:
- 1666 – Isaac Newton demonstrates that white light splits into a rainbow spectrum of color when passing through a prism, establishing that color is intrinsically tied to wavelengths of light.
- 1802 – Thomas Young proposes the trichromatic theory, stating that human color vision relies on three types of color receptors in the eye.
- 1848 – James Clerk Maxwell demonstrates additive color by projecting three monochromatic lights onto a screen, proving Young’s theory that all colors derive from three primary hues.
- 1869 – Hermann von Helmholtz theorizes opponent color processes in the eye, establishing modern understanding of color vision mechanisms.
- 1855 – James Clerk Maxwell produces the first color photograph via subtractive color principles with red, green and blue filters.
- 1890s – Maxwell’s RGB color model evolves into commercial color photography and cinematography.
These pioneers paved the way for all later color science and technology. Today, their findings form the foundation of how color is reproduced and manipulated across fields like digital imaging, printing, lighting, displays and more.
Conclusion
Additive and subtractive color theories explain how mixtures of primary colored lights or pigments create a range of hues through different mechanisms. Additive RGB color deals with light emission, while subtractive CMY color deals with light absorption. Though opposite, the two theories are fundamentally intertwined and essential knowledge for any practice involving color. Mastering both additive and subtractive color mixing allows much greater control and precision for any creative color application.
