The relationship between violet and blue is complex, as these two colors occupy a similar part of the visible spectrum but have distinct properties. While violet has qualities of both red and blue light, most would not consider it to simply be a shade of blue due to key differences in how the eye perceives these colors.
The visible spectrum
To understand where violet and blue fall in relation to each other, we first need to look at the visible spectrum of light that humans can see. This spectrum consists of wavelengths ranging from about 400-700 nanometers (nm), with violet wavelengths at the short end (around 400-450nm) and red wavelengths at the long end (around 650-700nm).
Within this spectrum, blue light occupies wavelengths of around 450-500nm. So while violet and blue wavelengths overlap to some degree, violet extends further into the ultraviolet range below 450nm. This gives it a slightly shorter average wavelength than blue.
Perception of violet and blue
When it comes to human color perception, wavelengths of light are just one part of the equation. The eye has receptors called cone cells that detect different wavelengths and interact to produce all the colors we see. There are three main types of cones:
- S cones detect short wavelengths (violet, blue, green)
- M cones detect medium wavelengths (blue, green, yellow)
- L cones detect long wavelengths (yellow, red)
Violet light strongly stimulates the S cones while also producing some stimulation of the L cones. Blue also stimulates S cones but lacks the longer wavelength component to stimulate L cones. So while violet and blue are close spectrally, violet provokes a distinct response in the eye.
Additionally, the perceived boundary between spectral colors is not cleanly divided. The transition from blue to violet is gradual, with wavelengths around 470-490nm appearing somewhat intermediate. So there is no clear cut-off where blue stops and violet starts.
Traditional color classification
Historically, violet has been considered a distinct spectral color with its own name and identity. In 1666, English scientist Isaac Newton identified seven main divisions in the spectrum, with violet as one of those original seven colors alongside blue. Other traditional seven-color systems like the rainbow or ROYGBIV also treat violet separately from blue.
This separates violet as its own color category, rather than simply a type of blue. Many color order systems like the NCS or Munsell color spaces also give violet its own designation distinct from blue.
Modern color models
In modern color theory, violet is understood as a non-spectral color, meaning it does not correspond to a single wavelength of light. It sits at the end of the visible spectrum between blue and ultraviolet. On a color wheel, violet bridges the gap between cooler blues and warmer reds.
In the RGB color model, violet is created by combining considerable amounts of blue and red light. This reflects the dual stimulations of S and L cones that produce the perception of violet. The table below shows some examples of RGB values that generate violet colors:
|Color||Red value||Green value||Blue value|
In contrast, pure blue colors have low red values and high blue values. So violet is distinguished from blue by having a much greater red component, in addition to its high blue.
Uses and associations
Culturally, violet also has distinct connotations from blue. It is associated with spirituality, imagination, luxury, and nobility. Light violet shades are seen as delicate or romantic. In art and design, violet creates moods of mystery, creativity, and magic.
Blue is linked to qualities like stability, confidence, and professionalism. It has more everyday associations than violet. So while blue is a primary color and commonly used in things like corporate logos, violet is treated as a secondary color with more nuanced or whimsical uses.
In summary, while violet and blue are similar visually, violet has unique properties that distinguish it from blue both physically and perceptually:
- Violet wavelengths extend further into the ultraviolet range below blue
- Violet stimulates a combination of S and L cones, creating a distinct response
- Traditional color models categorize violet separately from blue
- In RGB color, violet combines high amounts of blue and red
- Violet has different cultural associations and uses than blue
So while violet is closely related to blue and shares some of its traits, it stands as its own distinct color with key differences in visual perception, color theory, and meaning. Referring to violet merely as a type of blue overlooks its nuanced status in color science and culture.