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Can red and blue make violet?

Colors have always fascinated humans. From using plants and minerals to create primitive paints in ancient times, to the development of modern synthetic pigments and dyes, manipulating color has been an important part of human culture. Two colors that have held particular significance are red and blue. So an interesting question arises: can these colors combine to make the elusive tertiary color of violet?

The Basics of Color Theory

To understand if red and blue can make violet, we first need to review some color theory basics. The color wheel is a useful tool for visualizing how colors relate to each other. The traditional RYB (red, yellow, blue) color wheel shows the three primary colors and the secondary and tertiary colors that can be created by mixing them.

On the RYB color wheel, red and blue are primary colors located opposite each other. When two primary colors are mixed together, they create a secondary color. For example, red and yellow make orange, yellow and blue make green, and blue and red are supposed to make violet. This is the basic color theory behind the idea that combining red and blue will create violet.

The Complexities of Pigment Mixing

While basic color theory states that red and blue make violet, real-world pigment mixing is more complex. Modern color science uses the CMYK (cyan, magenta, yellow, black) and RGB (red, green, blue) color models, which have different primary colors than RYB.

When working with pigments, paints, dyes, etc., combining colors follows a subtractive color mixing model. Each pigment absorbs or subtracts certain wavelengths of light. What we perceive as the color is the wavelengths that are reflected back to our eyes.

When red and blue pigments are mixed, what wavelengths of light are absorbed and reflected?

  • Red pigment absorbs green and blue light, reflecting red back to our eyes.
  • Blue pigment absorbs red and green light, reflecting blue back to our eyes.

So when red and blue pigments are mixed, the result is a dark color that absorbs most visible wavelengths of light. Rather than making violet, combining red and blue pigments actually produces a dark muddy brown!

The Impact of Light and Shade

Context also impacts color perception. Colors are influenced by surrounding colors and light conditions. A color will appear lighter against a dark background and darker against a light background. The impression of a color can also shift depending on lighting conditions.

While red and blue pigments combined make brown, the interplay between these colors and light can create the illusion of violet:

  • Small amounts of red against a dominant blue background can appear violet
  • Areas of blue shade next to dominant red can seem to take on violet tones
  • Bright red light combined with deep blue shadow produces a violet effect

So in the right context, red and blue can create the illusion of violet through contrast effects. But the actual blended color remains a muddy brown.

Mixing Paints vs. Mixing Light

An important distinction is mixing pigments vs. mixing light. As discussed above, combining red and blue pigments makes brown. But combining red and blue light produces a totally different result:

Red Light Wavelengths: 620-750 nm
Blue Light Wavelengths: 435-495 nm

When red light and blue light mix and overlap, the result is light composed of the combined wavelengths. And these wavelengths of approximately 435-750 nm align with what our eyes perceive as violet on the visible spectrum.

So while red and blue pigments don’t actually blend into violet, red and blue light combined together directly produce the wavelengths corresponding to violet.

Examples of Mixing Red, Blue and Violet

We’ve explored the science behind mixing red and blue. Now let’s look at some real-world examples of combining these colors to create violet effects:

C monitors and TV screens

Older CRT monitors and televisions provide a great example of mixing light instead of pigments. These displays use a red, blue, and green pixel system to create colors. Combining red and blue pixels in different proportions allows these screens to produce violet hues.


Laser light shows mix red and blue lasers to create vibrant violets. As concentrated beams of pure colored light, lasers vividly demonstrate red and blue light combining to form violet.


The vivid violets and purples in firework displays are produced through carefully mixing red and blue pyrotechnic compounds. Different ratios create a spectrum from red-violet through to blue-violet.

Electrical Engineering

In electrical engineering, mixing frequencies of red and blue light is used to create radiation in the violet spectrum. Optoelectronic devices take advantage of this to generate violet emissions from red and blue LEDs or lasers.

Color Photography

In color photography and film, pairing a red filter with a blue filter can create violet light effects. Photographers leverage this to intentionally shift red subjects towards violet tones.

The Violet Region of the Spectrum

So far we’ve discussed violet as if it’s a distinct color. But violet actually encompasses a range of wavelengths between red and blue on the visible spectrum. Combining reds and blues of different wavelengths creates different violet hues:

Color Wavelength
Red 620-750 nm
Violet 380-450 nm
Blue 435-495 nm

Mixing a longer red wavelength (near 750 nm) with a shorter blue wavelength (around 450 nm) produces a red-violet. Combining a deeper red around 620 nm with a mid-range blue wavelength near 475 nm makes a blue-violet.

The Role of Visual Cortex Processing

As we have seen, mixing red and blue can produce violet light. But do our eyes actually perceive it as violet? Recent research suggests our brain’s visual cortex plays an important role in color perception.

Cone cells in our eyes detect red, blue, and green light. But studies show the brain combines and interprets these signals, rather than color being a simplistic mapping process. Test subjects have been able to perceive impossible colors when red and blue patterns are processed in certain ways by the visual cortex.

This indicates color perception involves complex neural processing. So even when red and blue light mixes into violet wavelengths, the brain may still interpret the color differently.


Can red and blue make violet? As we have seen, the answer depends on the context:

  • Red and blue pigments combined make a brown color, not violet
  • But red and blue light directly mix to generate violet wavelengths
  • Adjacent red and blue areas can create the illusion of violet through contrast effects
  • Our perception of violet also depends on neural processing in the visual cortex

So while basic color theory says red and blue make violet, the reality is more complex. The relationship between these colors illustrates the fascinating intricacies and subtleties of color and vision.

Understanding how chromatic mixing works is key for fields like photography, cinematography, lighting, manufacturing, and more. As science continues to unravel the mysteries of color, we keep learning just how clever and remarkable the human visual system is.