|Strange times are these in which we live, when old and young are taught in falsehoods school. And the one man that dares to tell the truth is called at once, a lunatic and fool. - Plato|
History of Color Science
The Ancient Primaries
François d'Aguilon's Color Mixing Theory (1613)
Primary Colors are white and black (light and dark)
In 1613, a Jesuit mathematician names François d'Aguilon (1567-1617) of Brussels published Optics in Six Chapters. Part of his writings in this document addressed the behavior of light and color. In his study of color, he had the interests of artistic painters in mind.
According to d'Aguilon's color mixing theory, the "simple" (primary) colors are white and black, or light and dark. From these primaries, the "noble" hues of red, yellow and blue are mysteriously derived. By mixing the "noble" hues, we get the "composite" hues of orange (gold), green and purple.
This light and dark color theory was based on the writings of the times. Medieval books about optics were based on the ancient Greek philosophical texts, such as Plato's creation poem, Timaeus (390 BC), passages in the writings of Aristotle (350 BC) and the De Coloribus (On Color) (330 BC). Aristotle's theory consisted only of a vague framework which was not practical. It was not related to the practice or perspective of artists.
Artistic Painter's Writings
It wasn't until the early Renaissance that painters, rather than scholars, wrote about color and painting methods.
In 1390, Cennino Cennini published a description of how artists worked with color. He described seven colors. Four (black, red, yellow and green) were mineral in character. Three (lime white, the blues (ultramarine, lapis lazuli and azurite), and yellow) were colors which needed to be developed artificially. His "mineral" and "artificial" colors refer only to pigment colors.
Other writings described the primary colors of red (carmine or scarlet), blue and yellow. However, painters did not usually mix these primaries to create other colors because the pigments available at the time were not saturated enough to produce satisfactory colors.
Writings by painters from the Renaissance through the Baroque period did not discuss primary colors and color mixing. Rather they focused on specific preparations of pigments and their color effects.
Artistic Painter's Primary Colors
In 1664, Irish chemist Robert Boyle wrote that an artist's "simple and primary" colors were white, black, red, yellow and blue. He wrote that these colors could "imitate the hues (though not always the splendor) of those almost numberless differing colors" which we find in nature and use in art.
Artists and manufacturers of the 17th century understood that primary colors were colored substances (dyes or paints) with physical attributes the same as any other physical substance. Experiment and observation gave evolving understanding of color and color mixing.
18th Century Theories and Systems
In 1672 French critic Roger de Piles wrote that "drawing has rules based on proportion, on anatomy, and on a continual experience with the human form, whereas coloring has yet hardly any known rules." It wasn't until the 18th century that writings were published about the three primary or primitive colors and how to use those colors to create all other colors.
In the 18th century, artists became interested in theories about color and systems of color mixing which were more specific and gave clear directions on how to create colors. At the same time, because of the needs of the textile industry, chemists began experimenting in ways to create better dyes and pigments.
Sir Isaac Newton (Newtonian color confusions)
In 1704, Sir Isaac Newton published his Opticks which made several points about color.
The Source of Color is Light
He said that the source of color was not substances, but light. He demonstrated that the different colors of the spectrum result from light being refracted. He called this attribute of light refrangibility from the Latin word refringere which means the ability to be refracted. He said that each color has a specific angle of refraction when light passes through a prism or lens. He argued that orange or violet light were just as "primitive" as red and yellow because they cannot be broken down farther into a more basic color. Consequently, he said, there were more than three primary colors. He identified seven, in this order: red, orange, yellow, green, blue, indigo, violet.
Circle of Colors
Newton saw the color spectrum as a closed system. He attached the red starting point to the violet end point and made a "circle of colors." Where the red and violet overlap, he added the colors of magenta and purple which do not appear in the color spectrum.
There is no black or white in the circle, but the center is white, which corresponds to the result of mixing all light colors together.
Pigment or Surface Colors are the Result of Absorption of Light
He also demonstrated that mixing three or four light colors resulted in white light. His conclusion was that the perceived colors on a surface or in paint were the result of some colors being absorbed and others being reflected. Read more about additive and subtractive colors.
Misunderstandings and Attacks
Newton 's work stimulated other research about color. But what he observed and wrote about was often misunderstood. At times, it was vehemently attacked because it contradicted the cherished beliefs about color which had been held since the ancient Greek theories were expounded, that is, that colors are the result of mixing light and dark (white and black). It also challenged the traditional belief that color light mixtures were an illusion while pigment mixtures were real.
Misunderstandings and controversies continued until the early 19th century. Many misconceptions found their way into color theory during the 18th century.
Problems with Newton's Color Theory
Newton believed that there were seven primary colors, despite the fact that there is a continuous gradation of colors in the spectrum and that he believed no spectral hue was more or less important than any other.
Newton did not understand the difference between additive and subtractive color mixing. He mixed three or four color pigments together to create "white" which was really gray. He implied that there were also seven primary pigment colors which were the same as the primary light colors and that they would mix the same way. However, it was easy to demonstrate that this is not so. In fact, his adversaries tried to disprove his color theory by demonstrating that mixing pigments did not create colors according to Newton's theory.
Artists Adapted Newton's Circle of Colors
The combination of Newton's scientific authority and the potential usefulness of his circle of colors to artists kept his theory from being rejected outright. Artists adapted it to what they knew empirically. They modified his diagram to create a color wheel using the three primary colors of red, yellow and blue and placed the complimentary colors opposite them.
Brook Taylor (1685-1731), adapted Newton's circle of colors by replacing the spectral colors with matching paint colors. He attempted to explain Newton's geometrical approach to color as being a convenient guide for mixing paint. However, Taylor did not understand the fallacies of using a color wheel to create subtractive colors. Nor did he understand that different paint tints have different strengths and need to be adjusted to create the desired color.
The First Tri Color Printing Process
A German printer named Jakob Christoffel Le Blon (1667-1741) solved many of these practical problems. In 1725, he invented a way of using three different printing plates to create a color picture. Each plate was inked with one of the painter's primary colors, red, yellow or blue. He sometimes added a black one. With this process, he created full colored mezzotints. His method has become the basis for the tri colored printing we do today.
Le Bon was the first person to clearly state that there is a difference between additive and subtractive colors.
The Englishman, Moses Harris (1731-1785), published what he called the Natural System of Colours in 1766. He developed two color wheels, one using the three "primitive" colors of red, yellow and blue, the other using the three "compound" colors of orange, green and purple. His purpose was to make it easy to find a complimentary color, by looking directly opposite to the other side of the wheel.
Louis Bertrand Castel
A French mathematician, Louis Bertrand Castel (1688-1757) claimed that "Newton has reduced man to using only his eyes." He was strongly opposed to Newton's experimental approach, preferring Rene Descartes methods. Descartes believed that in science, we cannot use our senses because they can be inaccurate. Rather we must use our mind and use deductive reasoning.
Castel explained color by the use of a three color spiral along with a prism diagram to show that all colors could be explained by overlapping mixtures of red, yellow and blue.
Beliefs Die Hard
Even until the middle of the 19th century, color researchers were still rejecting Newton's color theory.
J. W. von Goethe (1749-1832) and George Field (1777-1854) continued to advocate the idea that all colors were made from light and dark. David Brewster argued in the 1840's that all spectral colors could be produced from red, yellow and blue colors of light. J.M.W. Turner (1775-1851), a Romantic painter, adhered to Goethe's system, using blue and yellow in his paintings to symbolize the spiritual nature of dark and light.
Hermann von Helmholtz
Aristotle's Theory and Epic Poets Finally Loose Their Grip
David Brewster's theory that all spectral colors could be produced from red, yellow and blue light was finally dislodged in 1852 (a year after Turner's death) when Hermann von Helmholtz published the results of his research which showed that mixing blue and yellow light does not create green light. Read more about Hermann von Helmholtz.
James Clerk Maxwell
James Clerk Maxwell devised a color top which he used to demonstrate how all colors could be made by a mixture of three primaries: vermilion (scarlet), emerald green and ultramarine blue. His color top consisted of wedges of these colors. As the top was spun, the three colors blended together, creating the new color.
There were some colors, though, which could not be produced by Maxwell's color top. He solved this problem by creating "imaginary primaries," that is, a color that was defined mathematically, but could not be put on his color top. Yes, it makes no sense, but it is accurate, since our mind does not see the output from the cones (color receptors), therefore, visual primaries are imaginary anyway.
This understanding was a crucial step in the development of color science and became a standard way of defining the mixture of all colors. Maxwell's work is foundational to modern colorimetry.
Grassmann's Laws involve additivity, proportionality and transitivity. They mean that, even though a color changes in appearance, a color match remains.
The Munsell Color System
In the late 19th century, Albert Munsell worked on developing a practical theory of color where colors could be defined scientifically. He defined a color in terms of hue, value and chroma, hue being the actual color (red, orange, etc.), value being how light or dark the color is, and chroma being how strong or weak a color is. Read more about the Munsell Color System.
W. David Wright and John Guild
Working independently in the 1920's, John Guild and W. David Wright set about to determine how people perceive color. Their work was used to define the Standard Observer, that is, a definition of how the "average person" sees color.
They had their subjects look through two holes in a box. In one hole, the subject saw a fixed light color. In the other hole was a light color which could be adjusted, using knobs controlling red, green and blue light. Their instructions were to adjust the three colors until what they saw through both holes matched.
They found that the same color could be created by many different combinations of the red, green and blue lights. This property of color is called metamerism.
Wright's and Guild's work was used as the basis of the CIE Color System.
CIE 1931 Color Space
In 1931, the International Commission on Illumination or CIE (or Commission internationale de l'éclairage, its French name), set about to define color mathematically for the first time. They wanted a way to be able to say, "I want this color (whatever it would be)," and be guaranteed that everyone understood exactly what that color was.
They used the data collected by Wright's and Guild's experiments to develop the CIE Color System, or the CIE XYZ Color Space. It became the international standard and is still used today.
From the CIE XYZ Color Space, the CIE Gamut Chart or Chromaticity Chart was developed. Read more about the CIE Color Space.
Speed of Light
Additive and Subtractive Colors
CIE 1931 Color Space
Spinning Color Top
Glossary of Color Terms
History of Color Science
Motion After Image
Munsell Color System
Color Optical Illusions
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