Color theory and the primary colors have been debated by artists, scientists, and philosophers for centuries. Traditionally, the primary colors have been defined as red, yellow, and blue. However, some argue that there are actually 7 primary colors instead of just 3. So what exactly are primary colors, and is there evidence to support the claim of 7 primary colors?
What are primary colors?
Primary colors are colors that cannot be created by mixing other colors together. When combined, the primary colors theoretically can create all the other colors on the visible spectrum. In traditional color theory, the primary colors are red, yellow and blue.
The primary colors were defined by Thomas Young in the early 19th century. Young’s theory of trichromatic color vision proposed that the eye has three types of color receptors that respond to red, green and blue light. This became the basis for the RGB color model used in TVs, computers and other devices.
The traditional primary colors
The traditional primary colors based on the RGB color model are:
- Red
- Yellow
- Blue
By mixing the traditional primaries colors in different combinations and proportions, all other colors can theoretically be created. For example:
| Red + Yellow | Makes Orange |
| Yellow + Blue | Makes Green |
| Blue + Red | Makes Purple |
The primary colors were later expanded upon by CMY color model (cyan, magenta, yellow) used in printing and ink manufacturing. But red, yellow and blue remain the traditional primary colors.
The case for 7 primary colors
While red, yellow and blue are well established as the primary colors, some argue that there are actually 7 primary colors, not 3. The theory of 7 primary colors proposes:
- Red
- Orange
- Yellow
- Green
- Blue
- Indigo
- Violet
This is known as the ROYGBIV sequence of colors. The evidence for this is as follows:
1. The visible spectrum of light
When white light is passed through a prism, it separates into the visible spectrum of colors from red to violet. The 7 colors listed above correspond to the bands of color seen in the visible spectrum. Isaac Newton was the first to demonstrate this with his experiments with prisms in the late 1600s.
2. The eye’s cone cells
The human eye has three types of cone cells that detect different wavelengths of light. However, research shows the peak sensitivities of the cone cells correspond more closely to red, green, blue and yellow – not the traditional red, yellow and blue. This lends support to a 4 or 7 primary color model.
3. Distinct hues
The 7 colors of the ROYGBIV sequence are all considered distinct hues, in that there are no other colors between them. Red blends to orange, orange to yellow, and so on. This indicates there is a distinction between each of these 7 colors that is not found in overlapping hues.
4. rainbows
Rainbows showcase the full visible color spectrum, and rainbows are commonly depicted and described showing the 7 color sequence of ROYGBIV. This provides artistic and cultural evidence for the 7 primary colors.
Do artists really use 7 primary colors?
While scientists and theoreticians may debate 7 primary colors vs. 3, what do artists actually use in their work?
Most artists continue to use the traditional primaries of red, yellow and blue as the basic colors for mixing paints and pigments. The traditional primaries provide enough range of hue, value and chroma to create a wide gamut of color.
Some artists have adopted a modified approach that uses the primaries of red, yellow, blue along with green. Four primaries allow more control of hue and value. But for simplicity and cost reasons, a three-primary palette remains the norm.
Conclusion
While the science may suggest 7 primary colors exist in nature based on the visible spectrum and the eye’s cone cells, convention still holds that the primary colors are red, yellow and blue. These three primary colors can mix to create all other hues, and are easily available and affordable as paints, pigments, dyes, and more. Most artists stick with the traditional primaries for practical purposes.
But the theory of 7 primary colors continues to intrigue those who want to understand the complexities of color and vision. And there may be future practical applications that come from understanding how the eye perceives color in terms of 7 primary hues. Until then, the classic primaries will likely remain the norm for creating and understanding color.
