Color addition and subtraction are important concepts in color theory and color mixing. When different colored lights or pigments are combined, the resulting color can be predicted using color addition. When colors are mixed together and some color is removed, this is called color subtraction. Understanding these principles allows artists, designers, and scientists to deliberately create, modify, and reproduce specific colors.
The Basics of Color Addition
Color addition refers to the process of combining different colored lights or pigments. When lights are added together, this is called additive color mixing. Common examples are combining the colored lights in theater lighting or in TV/computer screens. When pigments or dyes are mixed, this is called subtractive color mixing. Some common examples are mixing paints or inks.
In additive color mixing, combining different colored lights results in a brighter, lighter color. The primary additive colors are red, green and blue. Mixing red and green light makes yellow. Mixing all three makes white light. In subtractive mixing, combining pigments results in a darker, duller color. The primary subtractive colors are cyan, magenta and yellow. Mixing cyan and yellow makes green. Mixing all three pigments makes black.
The Additive and Subtractive Color Models
There are two main color models that help visualize color addition and subtraction:
- Additive color model (RGB): Used for light, video displays, etc. Combining colors makes lighter values.
- Subtractive color model (CMYK): Used for pigments and dyes. Combining colors makes darker values.
The following table summarizes the primary colors and results of mixing in the additive and subtractive models:
| Color Model | Primary Colors | Secondary Colors | Tertiary Colors |
|---|---|---|---|
| Additive (RGB) | Red, Green, Blue | Cyan, Magenta, Yellow | White |
| Subtractive (CMYK) | Cyan, Magenta, Yellow, Black | Red, Green, Blue | Black |
Color Addition in Additive Mixing
When colored lights are added together in additive color mixing, the wavelengths of light combine to produce new colors. The primary additive colors are red, green and blue, which represent the primary colors detected by the human eye. When red, green and blue light are combined, they make white light.
Some examples of additive color mixing are:
- Red + Green = Yellow
- Green + Blue = Cyan
- Blue + Red = Magenta
- Red + Green + Blue = White
Additive color mixing produces brighter, lighter colors. This is because the more wavelengths of visible light that are present, the closer the mix will be to white light. Computer monitors, TV screens, theater lighting and other displays work by mixing different amounts of red, green and blue light to produce a wide range of hues.
Color Subtraction in Subtractive Mixing
In subtractive color mixing with pigments and dyes, combining colors produces darker, duller colors. The primary subtractive colors are cyan, magenta and yellow. When these pigments are mixed together, they absorb wider ranges of wavelength, subtracting more and more light and approaching black.
Some examples of subtractive color mixing are:
- Cyan + Magenta = Blue
- Cyan + Yellow = Green
- Magenta + Yellow = Red
- Cyan + Magenta + Yellow = Black
The CMYK color model used in printing uses cyan, magenta, yellow and black pigments to absorb light and produce color. By layering these pigments on a white surface, a wide range of colors can be reproduced.
Color Addition and Subtraction in Paint Mixing
Understanding color addition and subtraction becomes very useful in paint mixing. For example, painters can mix primary paint colors together to make secondary or tertiary hues. Some examples of paint mixing are:
| Color 1 | Color 2 | Resulting Color |
|---|---|---|
| Cadmium red | Cadmium yellow | Orange |
| Ultramarine blue | Cadmium yellow | Green |
| Ultramarine blue | Alizarin crimson | Violet |
Painters also take advantage of color subtraction by adding darker colors to lighten a mix, or adding light colors to darken a mix. Some examples are:
- Adding white paint lightens any color
- Adding black paint darkens any color
- Adding orange paint to green paint makes it less saturated
Color Addition and Subtraction with Light
Colored light follows the principles of additive color mixing. Light can be subtracted by adding colors or dark surfaces. For example:
- A red spotlight + green spotlight = yellow light
- A white spotlight over a black surface = dim gray light
- A green laser pointer light through a red filter = black (no light)
Dimmer switches, color gels and other tools for theater lighting alter the color by adding or subtracting wavelengths of light. Stage lighting designers combine colored lights to evoke moods and illuminate performers and sets.
Color Addition and Subtraction in Digital Design
In digital design applications like photo editing, video editing and graphic design, the RGB color model is used. Colors are added and subtracted digitally based on combinations of red, green and blue light. Some examples are:
- In Photoshop, the Color Dodge blend mode adds color values together, making the image lighter.
- The Color Burn blend mode subtracts color, making the image darker.
- Using Curves adjustments, dragging the curve down subtracts lightness.
- The Hue/Saturation tool subtracts color saturation or specific hues.
Understanding how colors are mathematically combined in design software helps digital artists master techniques like color grading, compositing and color correction.
The Psychology of Color Addition and Subtraction
Interestingly, color addition and subtraction can have psychological effects. Additive color mixing using bright light tends to have an uplifting, energetic effect. Subtractive color mixing with dark pigments can create moody, solemn tones. Some examples are:
- Bright neon signs (additive RGB colors) feel lively, vibrant.
- A dark gray charcoal drawing feels somber, contemplative.
- Adding bright blue to a muted green paint lifts the mood.
- Mixing vibrant hues into neutral browns subtracts the excitement.
Color designers carefully use color addition and subtraction to evoke emotions and convey meaning. Bright hues attract attention while dark muted tones recede. Balancing lightness and darkness creates color harmony and interest.
Color Addition and Subtraction in Vision Science
Researchers studying human vision and color perception rely heavily on additive and subtractive color models. Important discoveries include:
- The trichromatic theory: the human eye has three types of cones that detect red, green and blue.
- The opponent process theory: our vision perceives colors as opposites – red/green, blue/yellow, black/white.
- Afterimages: staring at a color induces an opposite afterimage due to neural adaptation.
Vision scientists use color addition and subtraction in experiments to probe color sensitivity, contrast effects, color blindness and other phenomena. This provides insights into how the visual system and brain process color information.
Color Addition and Subtraction in Nature
The principles of color mixing also apply in the natural world. Some examples are:
- Mixing pigments from crushed berries or plants for dyes and paints.
- Butterfly wings adding blue and yellow scales to produce green.
- Subtractive mixing in bird feathers, reptile skins and mineral hues.
- Sunlight passing through dust subtracting blue light, making sunsets redder.
Experiencing such color interactions fosters curiosity about light, perception, and the endless variation of our natural world.
In Summary
Color addition using red, green and blue light produces brighter colors in additive mixing. Combining cyan, magenta and yellow pigments causes darker colors through subtractive mixing. These principles of combining colors underlie fields like photography, design, visual science and the natural coloration found in our world. A deep understanding of color addition and subtraction helps both science and art harness the wonders and beauty of color.