Primary colors: what they are, and their characteristics

A summary about primary colors and how we obtain and perceive them.

Color is a visual experience. That is, it is a sensory impression that occurs because we have three types of chromatic receptors in the retina: the cones. These receptors respond to very specific wavelengths.

Although most people see thousands of different colors, most of them are actually combinations of three essential colors: the primary colors. Here we will see exactly what they are, what color theories exist and the concept of the chromatic circle.

What are primary colors?

The primary colors are those that cannot be obtained by means of mixtures with other colors, which is why they are considered unique.For this reason they are considered unique and singular. However, it is possible to mix them together, obtaining a Wide range of shades with them.

Although the idea that the three primary colors are red, yellow and blue is well established in popular culture, in reality, these three are not the true pure primary colors. There are different chromatic models that, depending on whether the color is due to a material or light, the primary colors are one or the other..

What most chromatic models do have in common is that they defend the idea that there are always three primary colors, although different from model to model. This is because the human eye has trichromatic vision. This peculiarity is due to the fact that most people have three types of receptors in the retina that respond to very specific wavelengths of light: the cones.

Theories of primary colors

There are different theories about primary colors, being two the most influential: that of light colors, or additive theory, and that of pigment colors, or subtractive theory.

Additive theory

Light color is immaterial, created by sunlight or artificial light. Light colors are obtained from the sum of radiations of different wavelengths and in different proportions..

The primary colors within the additive system are red, green and blue, constituting the RGB model (Red, Green and Blue). These colors are in white light, and are obtainable if that same light is decomposed with a prism. In turn, by combining red, green and blue light we obtain a beam of white light.

The primary colors of the additive system can be combined in pairs, giving as secondary colors the following:

• Red + green = yellow.
• Red + blue = magenta.
• Green + blue = cyan.

Likewise, the absence of primary tones gives rise to the color black.. This is because the human eye is not able to recognize the tones in the environment if there is no light in the environment.

Because it is possible to play with lights to obtain different colors, this is the system used by devices that work through light emissions, i.e., screens.

Subtractive theory

The subtractive primary colors are those found in pigments and dyes, being magenta, yellow, yellow and blue.The subtractive primary colors are magenta, yellow and cyan, called the CYM model (Cyan, Yellow and Magenta).

In the past, color was believed to be a quality of the object. However, with advances in optics and it was discovered that the color we see in an object is due to the type of light reflected from it..

Depending on the pigment in the object, the white light that strikes the object is reflected incompletely. On the one hand, some light beams will be absorbed by the object itself, while others will be reflected. The reflection is what the human eye picks up, assigning it the color of which we see the object..

For example, let's imagine a magenta-colored object. As we have already said, white light has all the colors in it. This light, when it strikes the object, is partially absorbed, absorbing all the colors of the visible spectrum except magenta, which bounces back and is the one we end up seeing.

As with light colors, subtractive primary colors can be combined to form secondary colors.

• Magenta + yellow = red.
• Yellow + cyan = green.
• Cyan + magenta = blue.

Interestingly, from the combination of the subtractive primary colors we obtain, as secondary colors, the colors that are primary in the additive model. Inversely, by combining the additive primary colors we obtain, as their secondaries, the subtractive primary colors.

Unlike light colors, which combined result in a beam of white light, mixed pigment colors result in the color black.

Since these colors relate directly to the pigments of an object, the subtractive primary color system is used in pictorial or printed elements, such as paintings, banners, posters, etc., which are used to create a white light beam.such as paintings, banners, books, colors of industrial objects.

Traditional primary colors

Originally it was thought that the primary pigment colors were the same as the ones we have today in popular culture: yellow, red and blue.

In fact, the famous German philosopher Johann Wolfgang von Goethe defended this idea in his 1810 book Zur Farbenlehre ("Theory of Colors"). In that book he created a model that we could call RYB if it had succeeded (Red, Yellow and Blue), being represented in a chromatic circle and where they were joined to form other, secondary colors. This model would be the precursor of the current CYM model.

Although this system has become obsolete, it is still used in plastic arts, especially in courses focused on primary school children.

Psychological primary colors

The theory of psychological primary colors was expounded by Ewald Hering. In it, he included up to six psychological primary colors. included up to six psychological primary colors, grouped in opposite pairs, namely: black and white, red and green, yellow and blue, and blue and white..

Although this theory has not had much repercussion in the visual arts, it has had much repercussion in the study of visual perception, being demonstrable in practice. For example, if we stare at a green object and then look away to a white or black surface, the silhouette of the object remains fixed on the retina, but we see its opposite color, which would be red. This same process can be repeated with objects of different colors, appearing in effect its opposite color..

Origin of the chromatic circle

Isaac Newton was one of the first to study the primary colors and their derivatives, expounding his theory in his book Opticks: or, A Treatise of the Reflexions, Refractions, Inflections and Colours of Light (1704). In it, he he affirmed that there were seven basic colors in light, which were the ones that can be seen in the rainbowred, orange, yellow, green, turquoise, blue and violet. In addition to this description, he made great contributions to optics with the creation of the first chromatic circle.

The chromatic circle, as we know it today, arises from the primary colors. In this circle, the primary colors are placed in equidistant positions, where the mixture of two of them will give rise to secondary colors.. From the mixture of a primary color with its secondary a tertiary color arises.

Newton is credited with the discovery that the colors we perceive can be identified thanks to light, as we explained earlier in the section on subtractive theory. When light falls on an object with a certain pigment, it decomposes, bouncing the unabsorbed light and absorbing the rest. It is this unabsorbed light that gives color to the object in question.

Bibliographical references:

• Newton, Isaac (1998). Opticks: or, a treatise of the reflections, refractions, inflections and colors of light. Also two treatises of the species and magnitude of curvilinear figures. Commentary by Nicholas Humez (Octavo ed.). Palo Alto, Calif.: Octavo. ISBN 1-891788-04-3.
• Goethe's Theory of Colours: Translated from the German; with Notes by Charles Lock Eastlake, R.A., F.R.S. London: John Murray. 1840.