We explain what primary colors are and how our eyes perceive them. Also, what are subtractive synthesis and additive synthesis.
What are primary colors?
The primary colors are the “pure” colors from which all other colors are obtained. They are the simplest components of the visible spectrum, that is, the segment of light frequencies that the human eye can perceive.
The best known primary colors are red, yellow and blue, but this is only the case if you work with pigments. In other words: only if they use materials such as crayons, temperas, watercolors or oils, the primary colors are red, yellow and blue.
But when it comes to a screen, the primary colors are red, green and blue. And in the case of a print, they are cyan (a shade of blue), magenta (a kind of hot pink), and yellow.
The procedure of making colors by adding pigments directly or printing with inks is called “subtractive synthesis,” and it consists of “subtracting” light from white. There are at least two types of subtractive synthesis: CMYK and RYB.
The CMYK subtractive synthesis model is the one used in graphic printing procedures (i.e., in procedures for transferring inks to paper and other materials by means of plates or cylinders). In this model, the primary colors are cyan, magenta and yellow, in addition to black or key plate. This model is called CMYK for the acronym of these colors in English.
The RYB subtractive synthesis model is used in arts that manually apply pigments or paints to a support. In this model, the primary or pure colors are red, yellow and blue. It is called RYB due to the acronym of its colors in English.
The process of making colors on a screen is called “additive synthesis”, because it is generated from “light” colors, which start from black (the total absence of color) and go towards white (which brings together all the colors of the spectrum). The primary colors of additive synthesis are red, green and blue. This model is known as RGB for its acronym in English.
Primary colors are not an intrinsic property of light. Light is an electromagnetic wave that has a continuous spectrum of lengths, ranging from red to violet. Within this spectrum there are an infinite number of lengths, but the human eye can capture only a few.
Our perception of color is based on a mixture of signals that are sent to the brain. When light falls on an object, some wavelengths are absorbed and others are reflected. The reflected wavelengths reach our eyes, where there are ocular receptors capable of identifying red, green and blue light, and all colors are made from them.
Secondary colors
Secondary colors emerge from the mixture of two primary colors in equal parts. Depending on the color model, the secondary colors are as follows:
Traditional RYB model (subtractive)
- Green: comes from the mixture of blue and yellow.
- Orange: comes from the mixture of yellow and red.
- Violet or purple: comes from the mixture of blue and red.
CMYK (subtractive) model
- Green: comes from the mixture of cyan and yellow.
- Red: comes from the mixture of magenta and yellow.
- Blue: comes from the mixture of magenta and cyan.
RGB model (additive)
- Yellow. It comes from the mixture of red and green.
- Magenta. It comes from the mixture of red and blue.
- Cyan. It comes from the mixture of green and blue.
Tertiary colors
By combining a secondary color with a primary color in equal proportion, a tertiary color will emerge. The most common tertiary colors are.
- Turquoise: blue and green.
- Vermilion: red and orange.
- Carthusian: green and yellow.
- Amber: yellow and orange.
- Cochineal: red and violet.
color theory
There are two different ways to think about primary colors:
- Subtractive synthesis which assumes color in its physical form.
- The additive synthesis which understands color as light.
These two models give rise to the three most common types of primary color classification:
- The RYB subtractive model (from English red, yellow, blue).It is used in pigments in plastic arts.
- The CMYK subtractive model (from English cyan, magenta, yellow). It uses primary colors from synthetic inks used in graphic arts and all printing media. The letter “K” corresponds to the key plate or master plate on which the details of the impression are made, usually in black ink. This ink is added to the CMY model because mixing the other three colors does not produce a sufficiently deep shade of black.
- The RGB additive model (from English red, green, blue). Use the primary colors of elements that emit light, such as photographic and video cameras, analog televisions, digital screens, projectors and monitors.
Subtractive color synthesis
Subtractive color synthesis is the process of filtering wavelengths of white light. It is used in processes to add natural or synthetic pigments and inks to a support, directly or using instruments or machines. The superimposition of color layers subtracts or subtracts light intensity from the resulting color. When mixing colors, the surface absorbs more and more light and moves towards black.
The primary colors of RYB subtractive synthesis are:
- Red
- Yellow
- Blue
The primary colors of CMYK subtractive synthesis are:
- Cyan
- Magenta
- Yellow
Additive color synthesis
Unlike subtractive synthesis (in which wavelengths are filtered or subtracted from the primary colors), in additive or RGB synthesis wavelengths add up and produce new wavelengths which correspond to new colors.
Additive synthesis is used in devices that emit light, such as LED lights, televisions, monitors, projectors or any type of digital equipment with a screen. The sum of the three primary RGB colors monopolizes all the wavelengths of the spectrum which is why it produces white light.
The primary colors of additive synthesis or RGB are:
- Red
- Green
- Blue
References
- Albers, J. (2010). Color interaction. Alliance.
- Deng, C. (April 15, 2024). primary color. Encyclopedia Britannica. https://www.britannica.com/
