Primary and secondary additive colors refer to the three primary colors of light (red, green and blue) that can be combined to create all the colors we see on TV and computer screens. By mixing different amounts of the primary colors, all other colors can be reproduced. The three secondary additive colors are cyan, magenta and yellow. Understanding additive color mixing is important for anyone working in digital design, photography, videography or other fields that involve displaying color through light.
What Are Additive Colors?
Additive color mixing refers to the process of combining different colored lights to create other colors. This is different from subtractive color mixing with paints, dyes and inks, where colors are created by absorbing/subtracting certain wavelengths of light.
With additive coloring, the primary colors are red, green and blue (RGB). When you combine these three colors in different proportions, they can create the appearance of any other color. For example, red light mixed with green light appears yellow. Blue and green light mixed together appears cyan (light blue).
Additive color mixing takes advantage of the way our eyes perceive color from different wavelengths of visible light. It is the primary mechanism for creating color on TV screens, computer monitors, projectors and other display devices. The pixels on the screen emit different amounts of red, blue and green light to create millions of perceivable colors.
Primary Additive Colors
The primary additive colors are red, green and blue (RGB):
Red – The longest wavelength of light that humans can see, corresponding to warm colors.
Green – Middle wavelength between red and blue.
Blue – Shortest wavelength, corresponding to cool colors.
These primary colors correspond to the three types of cones cells in our eyes that allow us to see color. By stimulating these cone cells in different combinations, all the colors of the visible spectrum can be reproduced additively.
Red, green and blue are chosen as the primary additive colors because they align with the peak sensitivities of our cone cells. They also span the full range of the visible color spectrum.
Secondary Additive Colors
When you combine two of the primary additive colors in equal amounts, you get the secondary additive colors:
Cyan – Made by combining green and blue light.
Magenta – Made by combining red and blue light.
Yellow – Made by combining red and green light.
These secondary colors can also be thought of as the complements to the primary colors. For example, cyan is the complement to red, magenta is the complement to green, and yellow is the complement to blue.
| Primary Color | Secondary Color |
|---|---|
| Red | Cyan |
| Green | Magenta |
| Blue | Yellow |
The secondary colors are useful because they create a larger gamut of colors for displays. For instance, mixing different amounts of cyan and red allows you to produce a wide range of distinct shades ranging from violet to blue.
Additive Color Mixing
Understanding how the primary and secondary additive colors combine is essential for digital color work. Here are some examples of mixing different pairs of additive colors:
Red + Green = Yellow
Combining pure red and pure green light creates the appearance of yellow. On a pixel level, this means the red and green sub-pixels are turned on at full brightness, while the blue sub-pixel is turned off.
Red + Blue = Magenta
Mixing red and blue light together produces magenta. The red and blue pixels are turned on, while the green is off.
Green + Blue = Cyan
Cyan results from mixing green and blue only. The red pixels are turned off.
Red + Green + Blue = White
White light contains a balanced mixture of all the primary colors. To display white on a screen, the red, green and blue sub-pixels are turned on at full brightness and blended by our eyes.
By mixing the primary colors in different proportions, millions of distinct shades can be reproduced additively. displays with more bits per color channel can produce finer gradations between colors.
Advantages of Additive Color
There are several key advantages to additive color mixing with light versus subtractive color mixing with pigments:
– Wider gamut – The range of producible colors is greater with combining colored light. Additive RGB monitors have a broader gamut than CMYK printing.
– Brighter colors – Mixing colored lights results in brighter and more saturated colors than overlaying paints/inks which absorb light. Displays can produce vivid colors that aren’t possible with printing.
– Efficiency – Emitting specific wavelengths of light is an efficient way to create color electronically. Small amounts of RGB phosphors or LEDs can produce a vast spectrum.
– Adaptability – Pixels can be controlled digitally and dynamically changed to display any color. This enables effects like animation and video.
Overall, additive color provides a very flexible system for creating color electronically with light. It forms the foundation for all emissive color technologies like TV, monitors, projectors and more.
Disadvantages of Additive Color
While having many advantages, there are some disadvantages to keep in mind with additive color:
– Light sources needed – Unlike pigments, additive color requires a source of light like a backlight or LEDs. This often requires more power.
– Fades with brightness – As displays are dimmed, additive colors become weaker and less accurate. Subtractive CMYK colors remain relatively consistent.
– Metamerism – The same additive color can be created with different mixtures of primary colors. But these colors may look different under alternate illuminants.
– Environmentally sensitive – Ambient lighting conditions affect the appearance of on-screen additive colors, whereas printed CMYK colors remain the same.
Additive color is also not very useful for static illustrations, printing, painting or other mediums that don’t emit light. Subtractive color mixing is required for any non-emissive color process.
Comparison to Subtractive Color
Subtractive color mixing relies on pigments, dyes, inks and filters that absorb certain wavelengths of white light and reflect the remaining visible wavelengths. For example, a cyan pigment absorbs red light while reflecting blue and green.
The primary subtractive colors are cyan, magenta and yellow (CMY). By overlaying these colors in different amounts, a full spectrum can be reproduced. The secondary colors are red, blue and green (RGB).
The key differences between additive and subtractive color systems:
| Additive (RGB) | Subtractive (CMY/RYB) |
|---|---|
| Light emitting | Light absorbing |
| Combines colors by adding light waves | Creates colors by subtracting wavelengths |
| Primaries = Red, Green, Blue | Primaries = Cyan, Magenta, Yellow |
| Secondaries = Cyan, Magenta, Yellow | Secondaries = Red, Green, Blue |
| Higher saturation | Lower saturation |
| Used for TVs, monitors, projectors | Used for printing, painting, dyeing |
Both color systems rely on the trichromatic theory of human color vision. But additive utilizes light while subtractive utilizes surface pigments to manipulate the appearance of color.
Uses of Additive Color
Because it involves emitting light, additive color is used in any application where color is produced dynamically through an emissive surface:
– TV and computer monitors – All display screens combine RGB phosphor dots or LEDs to create colors additively.
– Digital projectors – Video projectors shine separate red, green and blue lasers or lamps onto a screen to render color through additive mixing.
– Smartphone/tablet displays – The LCD and OLED displays use RGB pixels to render images and video.
– Digital signage/billboards – LED billboards can display full color imagery using clusters of red, green and blue LEDs.
– Stage/theater lighting – Intelligent RGB stage lights allow lighting designers to create colorful scenes and effects.
– RGB LED lighting – LED bulbs and fixtures that can produce any color by blending red, green and blue chips.
– Laser/water shows – RGB lasers projected through fog/water create brilliant light shows by scanning additive colors.
Any application where variable, controllable colored light is needed – additive color mixing allows the full spectrum to be reproduced digitally.
Additive vs. Subtractive in Design
Understanding the difference between additive and subtractive color is important for anyone working in design or visual media. While our eyes perceive the results similarly, the two systems have key distinctions in how color is produced and optimized.
In print design and photography, the subtractive CMYK process is used. Colors are reproduced by mixing cyan, magenta, yellow and black inks. RGB colors must be carefully converted to CMYK to compensate for the smaller gamut.
In digital/display design, additive RGB color is optimized. Pure cyan, magenta and yellow are outside of the RGB gamut, so conversions are required when translating CMYK images to RGB.
In general, additive color produces brighter, more saturated results than subtractive color. But it also depends greatly on lighting conditions. Subtractive pigments look relatively similar under any lighting environment.
Understanding these nuances allows designers to best match colors across print and digital media. Mastering both additive and subtractive color spaces is key for modern multi-media design.
Conclusion
Additive color mixing underpins all electronic displays and light emitting technologies. Combining red, green and blue light in different amounts allows the full spectrum of colors to be reproduced additively. This process exploits the way our eyes perceive color through cone cells in the retina. By controlling pixels digitally, endless color variations can be produced dynamically.
While subtractive CMYK colors rely on reflected light off pigments, additive RGB colors directly emit light waves to stimulate color vision. This allows for more saturated hues and greater adaptability, enabling the vibrant colors we see on TV, phones and computer displays. Understanding the additive primary colors, secondary colors and how they mix creates the foundation for working in digital imaging and design.
