A Guide to Color on Postcards

Despite the investigations by philosophers, theologians, artists, and scientists for over two millennium, most of us just take color for granted. This is not to say that we haven’t developed our own likes and dislikes or to deny that color can on occasion wow us; it is just that we don’t tend to think about color past our initial responses to it. The colors that found their way onto the surface of postcards might seem a simple matter of attempting to match them to reality or of personal taste, but these decisions were largely made in relation to prevalent color theories of the day whether they were properly understood or not. While most theories were based on scientific principals the results usually only revealed partial truths, and even then they were sometimes skewed by concepts of spiritual order that scientists refused to give up. Centuries of practical experience in working with paint and inks often had more influence on the decisions printers made, especially since most theories did not yield expected results when applied in real life. After the field of advertising grew into an industry in its own right, marketing surveys would also proved influential in making color choices. At the turn of the 20th century, when postcards were at the height of their popularity there was no shortage of ideas from where a printer could draw his pallet from; the problem was that a number of competing theories and ideas were all in vogue at the same time. New insights were slow to spread and many fell on the deaf ears of those reluctant to give up their familiar ways and notions. Even today, what most of us think we know about color is probably incorrect.

Before this presentation continues the reader must be aware of the fundamental issue that clouds all further discussion. Color is not an inherent component of physical objects but exists only as the minds reaction to being stimulated by particular wavelengths of the electromagnetic spectrum that hit the neuron receptors in the retinas of our eyes. Species that have evolved with different types of receptors perceive a slightly different range of this spectrum. Much recent study has also shown that there is much variation between how individual humans react to light stimulus, making color a very personal matter. Scientific theories that espouse absolutes in regard to color can in fact never be considered universal in their application.

DEFINING COLOR

ELECTROMAGNETIC SPECTRUM

Electromagnetic energy expresses itself in a wide range of frequencies that cover radio waves, microwaves, inferred light, white light, ultraviolet light, x-rays, and gamma rays. Of these the human eye is capable of perceiving only a narrow band within the white light spectrum that is usually referred to as visible light. Other species may perceive slight shifts in this electromagnetic range or more limited amounts of it. White light can be further subdivided into narrower frequencies that we experience as individual hues.

Compound Light: Since we experience light in the natural world as white there is a tendency to attribute color to objects but this is incorrect. Objects only seem to have color because they absorb specific frequencies of white light and reflect others back to our eyes. It is compounded white light that contains all the wavelengths we perceive as color as seen in a rainbow.

Humans have evolved with the ability to perceive this particular range of the spectrum in terms of color to help gain a more accurate understanding of the environment we exist in. We do not only experience color as light and as objects, but it accompanies our experience of contrast leading to our comprehension of space. While this elaborate adaptive process does not accurately portray the actual world, it allows us to make enough sense of it to function and survive in a virtual copy of it.

BASIC CHARACTERISTICS OF COLOR

Colors are usually discussed in terms of these basic characteristics but they do not by any means correspond to the full range of perceptions by which we personally judge color.

Hue: A hue generally refers to the average or strongest wavelengths of the visual spectrum resulting in any pure color. These peak hues do not all fall within the same value range though they are all capable of being altered by adjusting their chroma or value. This term is often used informally as a synonym for color.

Hue: These spectral hues are all shown with similar chroma and value.

Chroma: This term refers to the level of purity of a single hue. A pure color has a high chroma or saturation. As it becomes infused with its complimentary color of the same value its chroma incrementally decreases until it turns a neutral grey. Adding black will also decrease saturation but it will darken its value at the same time.

Chroma: As a complimentary hue is added to a highly saturated blue, it looses chroma but value remains constant.

Value: The tonal quality of a color is referred to as its value, which can range from light to dark. Any two hues of the same value will be indistinguishable from each other if captured on black & white film. Visual interpretations of objects in space are made in part by observing contrasting values.

Value: As a hue darkens in value it looses chroma.

Temperature: Artists much more than scientists characterize colors as being warm or cool. Warm colors tend to be described as the hues of yellow, orange and red that peak at red orange and that contain no visible blue or green. Cool colors are hues of blue or green that peak at blue green containing no visible yellow or red. There are not only exceptions to this rule but also no consensus to even if this is true. This characteristic is ultimately relative as it can be easily manipulated by a hues relationship to other colors.

Physicality: Characteristics of gloss, opacity, translucency, opalescence, iridescence and fluorescence are all visual components that may affect the way color is perceived. These factors however have rarely played any role in scientific theories concerning color.

PRIMARY COLORS

Up until recently all scientific theories of color revolve around the principal that all colors can be created from a limited number of specific colors. These specific colors, usually three in number are referred to as primaries as they cannot be created through the mixing of other colors. The hues considered to make up these primaries have not however been consistent over time. Few if any distinctions were made between the qualities of additive and subtractive colors until the late 19th century. The four main color groupings that were important to printers of postcards are discussed below.

Artist Primaries: Artist or material primaries of red, yellow, and blue (RYB) were used by artists long before they became the subject of true scientific inquiry. While there had been a variety of speculation as to why these three hues should be used as primary colors since ancient times, the choice may have had more to do with the availability of pigment and how they each chemically reacted with one another. Even though this pallet would latter be found have no relevance to the ways in which light is sensed by the receptors in the retina and the way color is perceived by the mind, they remained the more common choice among artists and printers halfway through the 20th century because of their practicality.

Artists Primaries: This early lithograph was printed with red, yellow, and blue inks. These colors were informally known as Artists Primaries because of their common use among artists long before scientists proposed other primary models.

Additive Primaries: Additive color theory is solely based on the affects that light stimulus has on human color perception, and should not be confused with the actual properties of light. Primates have cone shaped neural photoreceptors in their retinas that are most sensitive to wavelengths in a greenish yellow, green, and blue violet range. The additive color model however is based more on tradition than science, which gives us four cardinal lights consisting of red orange, a middle green, and blue violet. It is only out of expediency that we reduce the three additive primaries to red, green, and blue (RGB). White light, the mixture of all three of these colors is often considered the fourth primary that defines the tinting strength. When additive primaries are equally mixed together they produce all visible wavelengths, which are perceived as white light (compounded light). When only two additive colors are mixed in the eye, a third color is made visible in the form of a secondary additive color; blue plus green makes cyan, red and green make yellow, and blue and red create magenta. This trichromatic theory states that all possible colors can be made visible to the eye by combining different proportions of just these three additive primaries. Since the eye&rsqu;s response to measured wavelength stimulus can be mathematically calculated, this theory formed the foundation of much further scientific inquiry.

Additive Primaries: This illustration demonstrates the mixtures of additive light. If a reflective surface is illuminated by both the red and green lights, but not by the blue light, then the eye responds with the color sensation of yellow. A magenta color will result from the mixture of red and blue violet light, and cyan from the mixture of blue and green. The mixing of all light wavelengths from the red, green, and blue parts of the spectrum adds luminosity while negating hue thus shifting the color mixture from dim pure hues toward bright whites. The key principle is that the eye always adds all the wavelengths of light stimulus together on the retina, which will then be interpreted as color.

Subtractive Primaries: Where additive color explains how the mind perceives hues from reflected light projected into the eye, the principals of subtractive color are meant to supplement this theory by attempting to explain how color mixes in relation to light absorbent substances. Any color can be made by subtracting varying proportions of one or more of the primary subtractive colors, cyan (blue green), magenta (red violet), or yellow, (CMY) from compounded white light. This is the principle that governs the mixing of all colorants. We see objects as having color because they absorb (subtract) and reflect the visual spectrum differently. The primary subtractive colors act like filters that absorb their complementary colors of red, green, and blue which compose white light. An object that absorbs only one complementary color reflects the combination of the other two back. An object that absorbs two complementary colors will reflect the remaining complementary back unchanged. For instance if the sensation of red needs to be produced on a printed surface then blue and green need to be subtracted from the compounded light before it is reflected back to the eye. This is done by printing yellow, which absorbs its complement blue, and printing magenta, which absorbs its complement green. Thus the printed combination of yellow and magenta produces an optical red. In this same manner cyan and yellow will produce green and cyan and magenta will produce blue allowing all of the RGB primaries to be reflected back to the eye for interpretation. If no colors are absorbed they will all reflect back as white light, but when all three complementary colors are combined then all primaries are absorbed resulting in black (Lux nulla). In general CYM colors print much lighter than RGB, which in turn increases their reflectance to produce brighter colors, thus their preference in printing. These principals can be unreliable in practice, as a mix of CYM colors cannot produce all hues such as good oranges or purples.

Subtractive Primaries: In this illustration we can see how CYM primaries combine to create the RGB colors our eyes are receptive to. When cyan and magenta are mixed, red and green are subtracted yielding blue. When cyan and yellow are mixed, red and blue are subtracted yielding green. When magenta and yellow are mixed, green and blue are subtracted yielding red. When light wavelengths from the cyan, yellow, and magenta parts of the spectrum are all mixed together, luminosity is subtracted, shifting pure hues toward black. Subtractive mixtures always decrease both the value and chroma of colorants.

The true relationships between subtractive colors are very complex and while these principals should explain how all colors mix it is based on ideal conditions that never exist in the real world. The light absorbing properties of all colorants can be affected by pigment size, opacity, density, the medium it is dispersed in, how thickly it is applied, and even the color of the substrate it is placed on. Two colorants of the exact same hue will not combine in the same manner if their chemical composition differs Until they are physically combined the final outcome of any mixture cannot be predicted so universal mixing rules cannot be applied to subtractive colors.

The equal mixture of two of the RYB primary colors will produce secondary colors of orange, green, and violet. Tertiary colors are formed from equal mixtures of two secondary colors. There were however problems with this concept from the very start. Those who actually worked with colorants found that similar but different colors worked as primaries, that there were ways that primary colors could be mixed from other colors, and that not all colors could be mixed from only three primary colors. The scientific community largely ignored these practical observations for centuries because they did not fit into their preferred models that worked with pure idealized colors. Printers likewise often ignored scientific theory in favor of their own empiricism. Printers had no choice but to work with the colorants that were available to them in the form of ink, and what they chose as their primary colors was somewhat arbitrary. Almost any three colors can be used as primaries in printing to achieve a reasonable looking print though each set of colors will result in a different gamut. Our eyes can accept these arbitrary variations often without notice as long as the relationship between color, contrast, and subject meet our contextual expectations. It is the mind’s comparison between stimuli that creates color more than the mixtures of specific wavelengths of energy. Many painters had used four primaries of red, green, yellow, and blue for centuries and the printing trades picked up this tradition. Scientists and printers each used what worked best for them. In discussing their use it is more important to consider what people believed in rather than whether primary colors actually exist.

Psychological Primaries: The psychological primaries or unique hues are based on opponent color theory developed by Karl Edwald Konstantin Hering in 1892. This was his response to the solely quantitative approach to studying color that had become prevalent by the latter 19th century along with the inconsistencies that came along with it. His starting point would be to observe how color is actually experienced. Based on these findings he stated that the primordial opposite pairs of red green, and yellow blue are unique in that all other colors are perceived by the human eye arise from their combinations. The mind cannot perceive these opposites simultaneously but will interpret the differences in response time between the initial stimulus and the afterimage as more complex forms of color. It is only through these calculated differences that the mind can perceive a full spectrum of color through the limited receptor cones in the eye. Black and white were later added to his mix, not as opponent colors but because they could create veiled colors by lowering chroma into tones of grey. It was not until 1976 when color models could be based on actual electronic measurements of spectral emissions that these ideas were incorporated into Trichromatic Colorimetry. They now have practical implications on all forms of digital color reproduction.

Opponent Colors: Opponent theory is based on the principal that a color perceived by the retina can't be red and green, or both blue and yellow at the same time. As the nuances of this opposition along with changes in luminance are translated by the optic nerve it creates the perception of all colors in the brain.

SYMBOLIC COLOR

Attaching symbolic meaning to colors is an age-old practice used for much of recorded history as a unifying agent within a culture or even subculture. This approach to color was no different during the years of postcard production, but by this time so much of this symbolism had been recorded and exchanged that there was no longer any universal consensus as to what any of it meant. Differing symbolic applications of meaning and multiple associations existed simultaneously within any given group. In the United States today we usually make strong associations of the color pink with girls and blue with boys but only a hundred years ago these color assignments were often reversed. Colors often had political associations, which came and went with the tides of fortune. Red, long associated with Communism and the political left has suddenly been transformed to represent its long-standing opponents on the Republican right within the United States. The actual matching of color to meaning is sometimes more obvious as in blood red representing life, but the symbolic value placed on some colors simply had to do with their scarcity. The most rare colorants of any age often had the highest ritual value. While there are many postcards that used color in a symbolic fashion their pallets for the most part followed more practical concerns within the printing trades.

Blue: In Germany color symbolism had been a very important element of the Romantic Movement. Blue in this context was used as a strong masculine hue. It becomes important not to rush to judgment when evaluating 20th century printing where commercial concerns usually override symbolism. Does this postcard printed during World War One represent the German masculine ideal, or was blue ink just the cheapest to use or even possibly the only ink available due to wartime shortages?

Symbolism and allegory were not only important in the specific associations assigned to a color, but also in the ways concepts of structure were framed. In medieval times colors were used to represented perfection in both alchemy and theology. Many alchemical writings deal with the ordering of specific colors based on their model of an ideal world rather than empirical observation. This can also be seen in the Tree of the Sephiroth from the Cabala with its ten glowing globes of colored light symbolizing God. Black and white was used to represent complimentary forces within a whole in the East, while they often represent the dichotomy between evil and good in the religions of the Levant. Tonal transformation was sometimes used to represent the spiritual journey from sin to purity and the perfecting of the soul. The concept of the Holy Trinity elevated the status of the triad, which in turn resulted in many theories such as those concerning color to be modeled after this configuration. Some thought that there should be parallels of color to music in God’s perfect world and tried to structure notions of color around the diatonic music scale.

Symbolism: Most postcards of this simple type were usually printed in red, yellow, and blue, but here the blue was replaced with green. It is improbable that this substitution was made to conform to any theory of color, it is more likely attributable to symbolism as the pallet is the same as the Lithuanian national flag.

THEORETICAL COLOR

We know from the writings of Greek and Roman scholars that the concept of subtractive colors was already well known in the ancient world. These colorants however were not commonly used for mixing because the poor saturation of pigments at this time yielded poor results when combined. They may have only been chosen in the first place because few other choices were available and they proved sufficient for the jobs at hand. Some of the earliest writings concerning color come from Empedocles in the fourth century BCE. While he seemed to have an interest in actual chemical compositions of colorants, he still associated his four primaries, white, black, red, and yellow-ochre, with the four symbolic elements of fire, water, earth, and air. Plato would also reference a similar set of primaries but only as elements of beauty. Aristotle’s theories would be based more on observation but this seems true only up to a point. Instead of addressing hues in terms of primaries, he saw color in the relation of opposites; the absence of light, which is black or the presence of light, which is white. Light for him is only the medium by which colors can be seen because color itself rests within physical objects.

Aristotle’s dualistic approach would largely hold sway without question until the 17th century when attempts to improve on the colorants used in the Dying trades began in earnest. Textile manufacture had grown into a major commercial interest just as the scientific revolution was taking hold. Philosophers of the age, such as René Descartes influenced these matters with his mechanistic view of the world. If God would not deceive our perceptions with illusions, then we can come to understand color through our senses. This more practical approach led to the first true concept of primary colors that could be applied to colorants. While red, yellow, and blue (the artists primaries) would be adopted by many, there was still no clear consensus on this choice or on how these primaries should be used to mix colors.

RAINBOWS

Sir Isaac Newton was not the first to speculate on the nature of the visual spectrum for long before prisms of polished cut glass were available to experiment with, the same effects had long been studied in rainbows. Aristotle’s notes on natural color from the 4th century are some of the earliest surviving documents on this phenomenon, but it wasn’t until the later 13th century that the Persian astronomer, Qutb al-Din al-Shirazi began to provide more accurate insights. Even so for most of history it was difficult to understand why the ephemeral colors of rainbows behaved differently than the colors found on physical objects. Many would expand on the theories of both men but it was only after the Englishman, Thomas Young suggested that light could behave as an energy wave as well as a particle that rainbows were properly understood as two wave patterns interfering with each other. By the 18th century the study of color largely took place within the realm of scientific thinking but this by no means guarantied the accuracy of theories that arose from it. Many theorists conveniently saw what they wanted to see, selecting only the data that supported their ideas while ignoring any empirical evidence that might prove contradictory. Once a viewpoint was set down, its basic concepts were too often accepted without further questioning. Luckily there have always been those who continue to ask questions.

Double Rainbow: This card depicts the more unusual sighting of a double rainbow but with a major flaw. The arrangement of spectral colors in the second rainbow always mirrors that of the first. Even at this late date natural phenomena was still being represented by false notions rather than scientific knowledge that was already centuries old.

FRANCOIS DE AGUILON’S OPTICORUM LIBRI SEX - 1613

In the Opticorum Libri Sex, the Belgian Jesuit d’Aguilon primarily dealt with the application of geometry to optics in order to correct errors in relation to perspective. He did however elaborate on Aristotle’s basic colors narrowing them down to three simple hues of red, yellow, and blue situated between white and black. He diagramed them in the form of an arc to show they shared a similar relationship to that of musical consonants. While d’Aguilon was particularly concerned with the way colors actually appear to the eye, his ideas were tainted with notions that they contained a spiritual nature along with divine secrets. Though the RYG pallet was already considered important among artists for color mixing, his is perhaps the first written document in which these same colors are attributed with characteristics that would come to be called primaries.

NEWTON’S OPTICKS - 1704

The English physicist, Sir Isaac Newton had theorized since the late 1660’s that light was made up of particles that he termed subtle corpuscles as opposed to general matter made up of larger gross corpuscles. He believed that through an alchemic transformation one form of corpuscles had the capacity to change into the other. Twenty nine years later in 1704 he published Opticks in which he not only elaborated on these same ideas and those concerning light diffraction, but in which he demonstrated how white light was actually compounded and that it could be separated into spectral colors with the aid of a prism. He also expanded the theories presented here to include the concept of primary colors, and in this book is a diagram of his color wheel demonstrating how all colors can be generated from only seven spectral hues. Newton’s wheel was designed to demonstrate how the pure fiery colors on the outer edges of the ring were positioned opposite to their complimentary that would cancel out each others chroma in increasing degrees as they moved toward the center to form white. While his concept of complimentary colors was to prove valuable, he unfortunately did not elaborate on the effects that luminosity and tinting strength have on color mixes. These characteristics were different from one hue to the next and their positioning on a perfect geometric circle was not designed for accuracy. This combined with his general lack of specificity would lead many followers to confuse these experiments he made with light with applications to colorants that mixed in a more complex manner.

Newton’s Rainbow: In his book Opticks, Sir Isaac Newton gave a very elaborate description of how the colors of a rainbow would look depending on the relationship to spectator’s eye. Further studies of spectral colors were made with the aid of a prism.

Newton is usually given credit for approaching color with a mathematical perspective rather than by mere observation but this did not necessarily lead to more accurate results. Much of his early interests lay in alchemy and he incorporated the symbolic ties between light and sound into his thinking. Seven hues of red, orange, yellow, green, blue, indigo, and violet were placed on his color wheel to correspond to the diatonic musical scale. Despite this skewed vision Newton closed the debate on how large the range of possible colors might be by stating that all fundamental and mixed colors were derived from spectral hues. He also arrived at one of the most important conclusions in color theory that color is nothing more than the mind’s interpretation of stimuli, that neither light itself nor physical objects have any inherent color properties.

These new scientific theories proposed by Newton faced much criticism when first written. They were vehemently attacked by the supporters of more philosophical viewpoints first put forth by Aristotle and even Descartes whose scientific leanings were still infused with religious concepts. Experiments with prisms are not easy to carry out, and when others failed to duplicate Newton’s results they dismissed this upstart’s findings out of hand. His theories received further rejection when colorants failed to combine into the hues predicted by his color wheel not realizing it was meant to only describe the mixing of light. Even by 1739 the French Jesuit mathematician, Louis Bertrand Castel was still advocating trichromatic theory based on the musical circle of fifths. This debate over Newton’s theories continued well into the 19th century until his concept of compounded light was finally experimentally verified.

YOUNG’S THREE COMPONENT THEORY - 1802

The English physicist Thomas Young, who experimentally confirmed the wave theory of light, became an early proponent of the trichromatic theory in 1802. He thought it was impossible for the eye to contain individual receptors in the same number that would match up to the almost endless variety of colors that we experience. He proposed that all colors could be perceived through the blending of only a limited number of hues that stimulated the limited types of receptors scattered throughout the retina. While Young first narrowed down these colors into three primaries of red, yellow, and blue he had altered his choice in 1807 to red, green, and blue violet. In actuality the neuron light receptors in the eye are most sensitive to yellow green, green, and blue violet wavelengths. Young’s hypothesis only began to be researched in 1828 when the microscope became available to aid in the dissection of the eye.

GOERTHE’S THEORY OF COLORS - 1810

The ideas of Johann Wolfgang von Goethe as presented in his Theory of Colors published in 1810 were based more on sensory observation than scientific theorizing. His concerns centered on the importance of human experience over what he saw as the false invisible abstractions that were so readily promoted by science. For him Newton’s theories were not necessarily wrong, they just applied to very specific aspects of light and not to color as a whole. As with Newton the hues on his color wheel were balanced against their complimentary, but they were determined by the way they evoke each other as in the afterimages that forms in the eye. Violet is created from yellow, orange from blue, and green from red. Goethe also divided his color wheel in terms of light and dark spectra, as he believed colors arose like sparks from the battle between light and darkness. Yellow and blue were the two hues to first rise out of this mixture so they became his two primary colors. Newton, who only concerned himself with spectral colors did not consider magenta important but Goethe saw it as a natural result of violet and red being mixed in a dark spectrum and that it had practical if not scientific importance in rounding out the color wheel.

Goethe’s Color Wheel: While Goethe only recognized two primaries, yellow and blue, we can see in this illustration from his Theory of Colors the six hues that he considered important to perception. Among artists it still remains the basic model for the laying out of paint.

Goethe’s concepts regarding color represent more than a different way of looking at hues, they are reflection of the growing conflict between two different paradigms used to interpret the world. His rejection of what he saw as a mechanistic soulless science gained him adherents who had concerns well beyond that of color. Many artists were attracted to his ideas because its foundation in natural observation very closely resembled the same concerns they dealt with on a daily basis. Goethe’s concepts continued to remain popular with many artists for some time even though they do not add up to a coherent theory and they are full of inconsistencies. After 1840 when his Theory of Colors was at least partially translated into English, Goethe’s ideas gained much wider circulation and many more followers.

Goethe’s concepts regarding color represent more than a different way of looking at hues, they are reflection of the growing conflict between two different paradigms used to interpret the world. His rejection of what he saw as a mechanistic soulless science gained him adherents who had concerns well beyond that of color. Many artists were attracted to his ideas because its foundation in natural observation very closely resembled the same concerns they dealt with on a daily basis. Goethe’s concepts continued to remain popular with many artists for some time even though they do not add up to a coherent theory and they are full of inconsistencies. After 1840 when his Theory of Colors was at least partially translated into English, Goethe’s ideas gained much wider circulation and many more followers.

CHEVREUL’S LAW OF SIMULTANEOUS COLOR CONTRAST - 1839

The Law of Simultaneous Color Contrast published in 1839 by the French chemist Michel-Eugène Chevreul proposed that if one color was place atop another it would appear as if it was mixed with the complementary of the background color. This theory is based on the RYB primaries similar to Goethe’s color wheel where red is the compliment to green, yellow is the compliment to violet, and blue is the compliment to orange. So a red placed on a background of orange will gain a blue cast and appear a bit more violet because blue is the compliment to orange. When any two colors are exact compliments to one another this effect is greatly enhanced. Basically when we are exposed to more than one color at a time our perception is altered by contrasts of color and value. Unfortunately Chevreul did not make adequate distinctions between value and chroma when analyzing these effects.

Simultaneous Color Contrast: Both small red squares are exactly the same color but the one on the left should appear more violet because the eye infuses it with the complimentary of the background orange, likewise the one on the right should gain an orange cast because of its blue background.

This same principal is applicable when working with neutral tones, which is known as the contrast effect. It is based on the concept that everyone’s current perception of contrast will be influenced by a previous experience of contrast rendering all judgments as subjective. Place a medium grey against a dark background and will appear lighter, while the same medium grey placed on top a light background will appear darker.

Contrast Effect: Only three colors are used to create the squares against the grey on this diagram bur they appear to the eye as four. The small squares are exactly the same value as each other but the one on the left appears lighter than the one on the right because of the great differences in contrast between their respective backgrounds.

These changes in perception occur because of the desensitizing of the neuron receptors in the retina of the eye. When light is perceived as a value or as a color the receptor nerve fires, which creates a chemical reaction that sends the message of this stimulus off to the brain. As it keeps receiving the same visual stimuli the neurons ability to keep producing this chemical reaction quickly diminishes and it firing gradually slows. Because of this the eye will perceive any following stimulus in terms of successive contrast where a negative afterimage is formed. Staring at red for too long will create an afterimage of green, while a flash of bright light may result in the perception of dark spots.

Successive Contrast: Printers generally avoided printing large areas of bright colors next to each other to avoid the effects of successive contrast. Postcards printed in the Psychedelic Style during the 1960’s purposely placed bright complimentary colors next to one another to enhance this effect in order to evoke the experience of tripping out on hallucinogenic drugs.

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HELMHOLTZ THEORY OF COMPOUND COLORS - 1850

By the mid 19th century Hermann von Helmholtz was just one of the many psycho-physicists attempting to replace the notions espoused by the German Romantics regarding color with a answers based on a more quantitative approach. He expanded on Young’s ideas by creating color-matching experiments and discovered that only three different wavelengths are required to produce the perception of all colors. Helmholtz also agreed with Young that red, green and violet were the three additive primaries needed to produce the sensation of color. If the eye had only one type of color receptor the mind would have no concept of what color was, for everything would look exactly the same. To perceive any color at least two different types of receptors are needed so that the mind can compare different sets of incoming stimuli. It is only through this comparison that the mind can differentiate between wavelengths and their intensity to create the experience of color. Since the human eye has three different types of cone shaped receptors that seem to be able to differentiate between at least a hundred gradations of tone, it creates an incalculable number of variables, which allow the mind to perceive more than a million colors.

The Young-Helmholtz trichromatic theory of color vision had first been based solely on observation, and it would not be proven until 1956 when Gunnar Svartichin began experimenting on actual retinas obtained from fish. The scientific team of Dartnall, Bownaker, and Mollon would only confirmed this theory in relation to the human eye in 1983.

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GRASSMANN’S LAWS

The German, Hermann Grassmann studied the color theories of both Newton and Helmholtz with mathematical determination. He eventually came up with a number of principals that reinforced existing notions of additive light mixtures that would prove to be crucial in the further study of color mixtures. Perhaps the most important of these concepts was that for every hue of the spectrum there was another specific complimentary that matched it, and when combined white light would result.

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HERING’S OPPONENT PROCESS - 1892

Much of the work of Karl Edwald Konstantin Hering was done in response to the solely quantitative approach to studying color that had become prevalent by the latter 19th century. His starting point would be to first observe how color is actually experienced. His colleagues had already discovered the three different types of receptor cone cells in the back of the retina that were only capable of perceiving red, green, and blue, which became the basis of the RGB primaries. When Hering examined their work more closely he found inconsistencies that could not explain why people missing red or green receptor cones in their eyes were still capable of perceiving yellow. He also noticed that colors blend in very distinct pairings so that the eye can sense a reddish yellow but never a reddish green. Based on these findings he introduced his opponent color theory in 1892 stating that the primordial opposite pairs of red green, and yellow blue are unique in that all other colors are perceived by the human eye from their combinations. Black and white were later added to his mix, not as opponent colors but because they could create veiled colors by lowering chroma into tones of grey.

The three types of red, green, and blue receptor cones in the eye do not perceive individual color wavelengths exclusively but respond in some degree to their complimentary in coupled pairs. This is considered an antagonistic response as only one color will excite the neurons in the receptor and the presence of the complimentary color will inhibit a response in relationship to the amount of exposure to it. As a color is perceived the receptor gradually becomes desensitized to it and more receptive to its complimentary. The mind cannot perceive these opposites simultaneously but will interpret the differences in response time between the initial stimulus and the afterimage as more complex forms of color. It is only through these calculated differences that the mind can perceive a full spectrum of color through the limited receptor cones in the eye.

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ZONE THEORY OF COLOR - 1930

For many years the trichromatic theory of Helmholtz and the opponent process theory of Herring stood in conflict to one another and were hotly debated by proponents on both sides. It was not until the 1890’s that Johannes von Kries and G.E. Muller proposed that both concepts were fundamentally correct, that each theory only explained an important component of one single process. Kries’ 1904 law of coefficients specifically dealt with chromatic adaptation due to retinal fatigue, but he could not fully explain how this process worked. In 1930 Muller reformulated these same ideas into the more coherent zone theory in which he proposed that the stimulus retrieved by the three different photoreceptor cones (zone one) are transformed within the retinal cells of the eye (zone two) in a manner that creates opponent perceptions. All these newly created signals are then sent to the brain via the optic nerve (zone three) where they are interpreted as more complex colors. At first this idea was no more than speculation but after the International Lighting Commission adopted it as a standard in 1976 it has since become the foundation for most of the color appearance models used today.

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CLAUDE E. SHANNON’S A MATHEMATICAL THEORY OF COMMUNICATION - 1948

There have really been two basic approaches to dealing with color on postcards. One has to do with the pallet desired to be presented to the viewer, and the other deals with the ways in which these colors can actually be created through practical means. The first approach falls within the purveyance of artists and marketers while the later has primarily been the concern of both printers and scientists. With the exception of chromolithography that rendered images through local color, most printers dealt with some sort of color model derived from principals of human vision to produce their cards. Even when these models did not agree with one another they were still all based on fooling the eye into perceiving more colors than were actually put into use when reproducing an image.

While Claude E. Shannon did not directly address the problems of printers or even color directly, he delved into the process of communication with a qualitative and quantitative approach that clearly divorced information from meaning. His concepts revolve around how data can be transmitted with a minimal amount of structural complexity, encoded into some form of symbolic representation so it can be received with as little distortion (noise) as possible to render it decipherable. His mathematical formulas did not provide any practical means of actually doing this, just the probabilities of how well this could be achieved. When Shannon’s ideas were made public in 1948 there was little practical application for them, but as they became the foundation of information theory they would prove essential for the growth of digital technology.

For printers postcards are not about pictures, they are about the cost efficient transfer of information. An image is encoded into a series of halftone dots made up of specific hues placed down in a set fashion so that the viewer will be able to decode and read the visual message. Traditionally this technique was refined by simple trail and error, but by assigning it to a mathematical model these decisions could be calculated more accurately with error correcting methods factored in. This allowed age old concepts in printing to flow seamlessly into the digital age.

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JOSEPH ALBERS’ INTERACTION OF COLOR - 1963

The artist Joseph Albers spent years teaching the principals of color based on his own studies at the Bauhaus. His approach was not systematic as he saw color in relative terms. Light may behave according to rigid scientific principals but we all react to it in very personal perceptual ways. Instead of proposing theory he felt that it was only through direct experience that one could discover how colors interact. Through his own work as an artist and experimental demonstrations he tried to help train the eyes of others to see that there is no one visual truth. While he had little to no influence on commercial printing, Albers became very influential within the art world and his ideas have altered the public’s perception of color to some degree.

COLOR SYSTEMS

While many have contemplated the essence of color or carefully studied the nature of pure colors and the manner in which the eye works, there were always a great many more painters, dyers, and printers who had to deal with the more practical aspects of color on a daily basis. As most theory dealt with idealized forms of light that were never as pure in the real world it was difficult for those actually working with colorants to apply much of this knowledge to their craft. A whole other tier of practical knowledge regarding pigments and dyes would form and expand alongside scientific discoveries. The mixing of pigments cannot be explained by exacting theories in physics alone for it is not really about combining colors as much as a matter of chemistry. While the mixing process is highly unpredictable some sort of framework was still needed for artisans to carry out their craft and pass on learned experiences. Most of this structure was built upon the simple method of trial and error found in day-to-day working experiences. It was much more important for someone trying to earn a living to know what worked than why it did. Sometimes there was a crossover of knowledge between science and craft but just as often these two very different worlds worked independently from one another and sometimes to cross-purposes. During the Renaissance the experiences of craftsmen and artists working with colorants finally began to be recorded. By the time postcards come into production there were many different ideas concerning how color should be used for there was no consensus on the true mechanics of perception. The discrepancies between theory and practice have never been completely resolved.

COLOR WHEELS

The basic concept that there are a select group of primary colors that can mix all others has existed since ancient times, but it was not until the 17th century that this idea began to be solidified into a workable theory. These artists primaries as they came to be known were based more on practical knowledge than scientific thought. Sir Isaac Newton rejected both the ancient Greek notion that colors arise from mixtures of light and dark, and the concept that there only three primary colors usually described as red, yellow, and blue. His conclusions that light has a compound structure that can be broken apart into seven separate spectral hues created the foundation for his color wheel, which opened up a whole new way of approaching the subject. He referred to each of his chosen hues as primitive because they could not be broken down into a more basic color, and that in combination they could produce all other colors.

Color Wheel: While the color wheel has been used to represent color mixing models for over 300 years, its pallet and shape has not remained constant over time. This wheel represents the common artists primaries where yellow and blue mix to form green, blue and red mix to form violet, and red and yellow mix to form orange. Even though this type of wheel is the one most of us are familiar with it has no validity in science.

Newton designed his color wheel to demonstrate the changes in hue and saturation within spectral light without any regard to the needs of artists. When these principals of light could not be reproduced in the mixtures of colorants the traditionalists attacked his ideas. They kept the model of his wheel but inserted their own preferred three primaries of red, yellow, and blue onto it. For many it was more important to uphold Aristotelian doctrine than admit that these three primaries cannot mix all colors. This model was soon expanded upon by others, and the absence of tonal and chromatic considerations was dealt with by placing pure hues around the circumference that would gradually move toward black or white at the wheel’s center. While adding black to any hue will darken it, the addition of white does more than lighten value it reduces chroma causing all these wheels to be skewed in some manner. In addition, the mixing of any two different hues on the wheel will also reduce chroma and value. With no direct relationship between light and colors mixed in pigment these color wheels did little more than add to the confusion. Even after more accurate modes were developed there were still problems, as the colorants in one medium did not mix in the same way like those in another medium. Many printers would develop their own wheels based on the straight colored inks they used in their shop rather than predicative mixtures.

BROOK TAYLOR’S NEW THEORY FOR MIXING COLORS - 1719

The English perspective theorist, Brook Taylor tried applying a more practical approach to Newton’s color wheel in the appendix to his New Principals of Linear Perspective. By matching the colors on the wheel to the available pigments of his day he hoped he could create a guide that could actually aid artists in their mixing of colorants, but he unfortunately followed Newton’s color choices without question. While Taylor recognized that the subtractive qualities of light did not coincide with the unpredictable nature of paint and stated as much in his writings, he did nothing to compensate for the unequal tinting strengths of different color pigments. In the end his well-intentioned guide proved worthless but it would encourage the trend of creating mixing guides for artists.

JACOB CHRISOFFEL LE BLON’S COLORITTO - 1725

The German printer, Jakob Chrisoffel Le Blon investigated Newton’s color theories to see if there was anything within that could provide him with an edge over his competition. While he never quite understood that color was not a characteristic of light, he did recognize that there was a real difference between the behavior of light from that of colorants. While it is known that some of his concepts had already been discussed since 1708, it is largely through his writing of Coloritto, also known as the Harmony of Coloring in Painting Reduced to Mechanical Practice in 1725 that they gained widespread attention. In his version of Newton’s color wheel emphasis was given to three primary (primitive) colors, red, yellow, and blue. By 1710 he had put theory into practice and was printing color mezzotints from three different plates, each inked with a different primary with the occasional addition of a fourth plate for black. This tricolor process was patented in 1717 but it did perform well as a commercial endeavor. Other printers eventually developed similar methods that also employed an additional black plate but they also failed to make a profit using it and the practice ended by the turn of the 19th century, at least temporarily. The color wheel however was by now an important model that many others would continue to tinker with. The simple RYB pallet that Le Blon worked with became popular once again in the latter 1900’s with the introduction of line block printing.

MAYER’S COLOR SYSTEM - 1758

In 1758 the mathematician and astronomer Tobias Mayer tackled the inherent problems found in the color wheel and designed a three-dimensional color system in the form of a triangle. This diagram took hue, chroma, and value all into consideration with colors moving toward white at the top and black at the bottom. While Mayer stated that his system could be applied to both colorants and light, this claim was based on the faulty assumption that red, yellow, and blue were the primaries for both colorants and light. Even without this basic problem he had much difficulty in matching actual pigments to his diagram’s needs. While Mayer’s work was refined and expanded upon by Johann Heinrich Lambert and August Ludewig Pfannenschmid it was still based on a problematic triad of hues.

Mayer’s Triangle: Tobias Mayer thought that color was more understandable in the form of a triangle when the essential characteristics of hue, value, and chroma were all taken into consideration. Unfortunately this model was based on the faulty assumption that light and colorants behave the same way.

A.G. WERNER’S NOMENCLATURE OF COLORS - 1774

With the growth of scientific concepts in 16th century Europe, the more curious men of leisure became self-proclaimed naturalists and began categorizing specimens of all kind. Some never wandered beyond the confines of their vast estates but other set off on journeys to hitherto unseen parts of the world in search of the new and exotic. Many of the minerals and plants discovered on this 300 year long quest had great influence on the manufacture of colorants. Not only were new dyes and pigments produced, a new method of standardizing colors was instituted in the form of an atlas to record all of it. In these books material objects like the flower of a particular plant or the shell of an insect could be matched to hand colored swatches of paint, and then given specific name for reference. In this way a standard language was developed when referring to hues. One of the first such color atlases was the Nomenclature of Colors published by A.G. Werner in 1774. This tradition continues today in color matching systems like those developed by Pantone, where standardized colors for printing and manufacturing are referred to by given number.

MOSES HARRIS’ NATURAL SYSTEM OF COLORS - 1766

Moses Harris in his Natural System of Colors, written in 1766 presented a more elaborate version of the color wheel. He preferred the format of the circle to that of the triangle for the contrasting possibilities of complimentary colors were more clearly defined. Like Le Blon he had given emphasis to the red, yellow, blue positioning them as far apart from each other as possible for they were the greatest of opposites. When any of these two are mixed they form secondary colors of green, purple, and orange, which are positioned directly between them on the wheel while sitting directly opposite their complimentary, but this balanced arrangement meant loosing Newton’s indigo as a 7th primary. Each of these secondary colors were then mixed into tertiary colors. The 18 hues yielded by this process were then shown in 20 different levels of saturation reaching toward a black center. Harris realized that there could be problems when applying the wheel to colorants, and that most tertiary colors would never be mixed but manufactured instead, but he still felt that this methodology was needed to create a more universal language of color.

Natural System of Colors: These two wheels of Prismatic and Compound colors were presented by Moses Harris in 1776. They were highly influential on those working with colorants because if the detailed approach taken. Unfortunately they are based on a faulty set of primaries.

Harris also designed a second color wheel, which was presented in the same volume to help artists understand the mixing properties of more muted colors. Here green, purple, and orange were used as the principal compound colors that could combine into brown, olive, and slate. Because of his practical approach this book came to be highly influential. His color wheels became well known and his choices of primary colors helped support the traditionalists in the growing conflict between the new science espoused by the Newtonian model and the more ancient teachings of Aristotle.

HAYTER’S A NEW PRACTICAL TREATISE ON THE THREE PRIMITIVE COLORS ASSUMED AS A PERFECT SYSTEM OF RUDIMENTARY INFORMATION - 1826

Charles Hayter, an artist and authority on perspective reinforced the theory postulated by Thomas Young that all colors could be obtained through the mixture of only three primaries. His 1826 publication on color contained three different illustrated wheels that also demonstrated the effect of adding in white and black from which a total of 182 colors could be mixed. Hayter however did not understand that Young’s theory only pertained to the additive mixtures of light and not the subtractive mixtures of physical colorants of which he wrote about. To confuse matters more Hayter chose RYB colors for his primaries, a pallet that Young had latter rejected in favor of one closer to RGB. Unfortunately Hayter’s book proved to be quite influential.

MAXWELL’S DIAGRAM OF COLORS

Through his studies of electromagnetic energy the Scottish physicist, James Clerk Maxwell designed an equilateral triangle in the 1860’s based on additive colors (Maxwell triangle) to take the place of the traditional color wheel. This concept was based on the tricolor principal that the mind perceived all colors through stimulus registered on only three types of receptors in the retina of the eye. Scarlet, emerald green, and blue violet were his chosen primaries that sat in each corner of this triangle. Between them sat all other colors in proportional mixtures based on proximity to the pure primaries in the corners and the white that sat in the triangle’s center. Because the tinting strength of the pigments used to make the triangle were all different, Maxwell had to lower the chroma of each hue until they were of equal saturation. While this reduced all the colors to a perfect mathematical balance, they no longer resembled what had long been considered the true primaries. In the Maxwell triangle it was the proportional relationships between hues that were important and not the hues themselves. Here the primaries are reduced to a conceptual context, which is how the mind perceives them. Despite his triangles limitations in dealing with higher intensities of color, these trichromatic principals of additive primaries became the standard approach to thinking about color by both artists and scientists in the late 19th century.

OGDEN ROOD’S MODERN CHROMATICS - 1879

Modern Chromatics, written by the American physicist Ogden Nicholas Rood in 1879 would be one of the more influential books on color for artists and printers alike. It proved of particular interest to the pointillist painters within Neoimpressionism who experimented with different ways to apply color dots to canvas so that they would optically blend into more vibrant new hues. Unlike Chevreul, who was also closely studied at this time, Rood made careful distinctions between hue, luminosity (value), and purity (chroma), considered the constants of color. Rood’s color system abandoned the usual RYB pallet found on most other color wheels in favor or red, green, and blue. He also stipulated that any two colors which by their union produce white light are called complementary, and these additive colors furnish the strongest possible contrasts. It was through these contrasts that the eye was most stimulated into perceiving color.

Pointalism: This postcard reproduces a neoimpressionist work painted by Paul Signac in 1909. Georges Seurat was the first to paint solely in dots in 1884 while attempting to achieve maximum luminosity in his work. The artists utilizing this style were far more concerned with color theory than their commercial counterparts that also produced chromolithographs through the accumulation of color dots. Though both methods are contemporaneous, there is little to no acknowledgment of each others work in their writings.

MUNSELL COLOR STSTEM - 1915

After studying and finding fault with the geometric color model of Chevreul, the American Artist Albert H. Munsell began work on his own color system in the 1890’s. He relied heavily on the work of Ogden Rood that emphasized the relationships between hue, value, and chroma. In 1905 Munsell replaced Maxwell’s color mixing triangle with a branching color tree that demonstrated perceived differences within each color constant. In 1915 he issued a color atlas that showed carefully laid out incremental changes in value and chroma for each hue and then matched it with its visual complementary. This atlas was revised and republished in 1929 as the Munsell Book of Color, and again in the early 1940’s, when it became the standard color reference system in the United Sates.

INTERNATIONAL LIGHTING COMMISSION (CIE)

The International Lighting Commission (Commission Internationale de l'Eclairage) was founded in 1913 to help continue efforts in bringing about a uniform color model among nations. Many years of conferences finally yielded results in 1931 with the introduction of the CIEXYZ color system that provided a standard for matching color against the values of only three additive colors, red, green, and blue. The system’s is designed to measure the relative intensity of the light source that corresponds directly to each of the three different types of neuron receptors in the retina of the human eye and translate the results into tristimulus values. This takes into consideration that the different types of cone cells in the retina are not just sensitive to different frequencies of light, but specialize in registering different intensities of luminance as well.

In 1976 the International Commission on Illumination developed two basic models of color space as used in colorimetry. One based on the older CIEXYZ from 1931 is CIELUV, which only approximates the old RGB primaries. It is based on measuring the response of the human eye to the luminescence of a light source and converting it into a mathematical formula, but the results obtained are only uniform if the luminance remains at a constant level. While the over representation of green in this model corresponds to the human eye’s particular sensitivities, it detracts from its efficiency in practical usage. It still is however commonly used in the color graphics viewed as light through digital monitors.

CIELAB: If one draws a straight line on the chromaticity diagram, then all the colors that lie on it can be formed by mixing the two hues that sit at the opposing endpoints in correct proportion to one another. To create a larger gamut a third point is needed so that the line can curve. All the colors that fall within a triangle can be created by a proportional mixture of the three colors that sit at its points. There are however no three points that can replicate the entire range of human vision.

The newer model is known as CIELAB, which is a combination of earlier opponent color theory with the latest discoveries into brain function. As the sensors of the retina receive visual stimulus it is translated by the optic nerve into distinctions between the opponents light and dark, red and green, and blue and yellow to create the perception of all colors in the brain. This model creates a uniform balance between hue, value, and chroma, which aims to replicate the entire spectrum perceivable through human vision. The output curves on devices with more inherent limitations such as monitors that use RGB colors and printers that use CYMK colors can be transformed by CIELAB into a uniform color spacing model that better predicts visual response.

MARKETING COLOR

Colors were used sparingly in early printed form largely because of the technical problems in dealing with it. As these problems were solved printing incorporated more and more color to attract an audience, which only encouraged the public to demand even more. By the 1880’s printing pallets had increased to enormous size, but as tastes changed and printers found they could get away with less they did so. With the introduction of the halftone a photograph could now carry an image and color became an afterthought. While many high quality cards continued to be printed, many more sought out ways to reduce cost by narrowing down the amount of printing plates used as much as possible. Many cards were printed with just enough color to make them work, and sometimes not even that. Color had become associated more with printing technique than with aesthetic results.

Poor Marketing: This hybrid postcard was made by printing a black halftone over tints or red, green, blue, and a fawn. There was no attempt to physically or optically mix these colors; instead they are placed down side by side with only a relative connection to what they visually represent. The outcome is neither realistic nor mannered, it just looks sloppy. Some printers thought they could get away with anything as long as it had color on it.

By the end of the 19th century the cost of printing illustrated material dropped substantially due to new technical innovations, and the amount of advertising presented to the public rose in proportion to it. The pallet an illustrator might choose was no longer solely based on artistic preference but on prevailing public moods captured by marketing surveys. Selling had become the primary goal and color had become an important tool to that end. Concepts such as color temperature, which had been of little concern to scientists suddenly, had psychological implications that could have an effect on sales. As bright warm colors became associated with the ability to attract and stimulate customers we began out trek into living in a more colorful world.

Good Marketing: This early process printed postcard was design to use color to good marketing effect. The background does not turn cool and grey to fade into the distance an in an academic painting; instead it remains warm and inviting to the viewer. While we can never know if the red and violet were added to specifically target women, it was women who purchased these glamour cards in greatest number.

These changing attitudes toward color would no longer have much effect on a printer’s pallet. Most shops had converted to photomechanical means of production and economic incentives would keep them there. Even though the choices of ink for printing were drastically reduced to one set of primaries or another, the way they were employed would change. Cards printed in red, yellow and blue, had to look as if they contained more colors, preferably those that the public were interested in seeing. This increased the importance of illustrators whose work would be reproduced, and retouchers who could make stylish cards out of ordinary black & white photographs. A dichotomy of cards would be created; those that were simply printed, which could be sold as cheaply as possible, and those accommodating fashionable taste. The more successful marketers learned that color needed to be used as more than a gimmick, that what the public wanted was an appealing image real or not. Trade magazines would even encourage publishers to order cards in small amounts so on reorder the pallet could be changed thus presenting customers with a new choice from an old image. In these cases color was completely divorced from reality being used as nothing more than a marketing ploy.

LUCKEISH’S LIGHT AND COLOR IN ADVERTISING AND MERCHANDIZING - 1927

The book, Light and Color in Advertising and Merchandizing published by M. Luckeish in 1927 talks to us about the appeal of color in very subjective terms that any scientist, and probably most artists for that matter would find appalling. To him some colors are dignified, depressing, stimulating, painful, repulsive, vivid, appropriate, attractive, realistic, useful, novel, distinctive, symbolic, and have innate appeal. Colors to him must be also used with a sense of propriety and good taste in dignified nature. While these notions do not add anything to color theory they do give us insight to the concerns of the times, and the trends that followed. Of more practical value, Luckeish did experiments on the color preferences of college students. The results are as follows:

Colors in Order of Preference Between the Sexes

It is difficult to ascertain how far early publishers took these surveys in planning the color gamut that would appear on their postcards. With few color photographs to act as guides the retoucher had much leeway regarding the choice of pallet and thus could be influenced by marketing concerns. We know today that the selection of color is so important to advertising that the manipulating natural color to meet marketing strategies has become routine. It can be assumed that earlier publishers may have had the same concerns and applied color in a similar fashion. While blue still remains the favorite color of men and red the favorite of women, problems arise when trying to codify this information into a system.

This is especially true when creating laws of color harmony. It has long been known that the combinations of certain colors evoke favorable responses while others do not. An artist may intuitively know what combinations work well but the variables are too great to catalog and their effect is never absolute. We have already seen that men and women have different preferences when it comes to color so how can they find agreement as to what hues are in harmony with each other. Many other contextual factors also play a role on how colors are perceived. This however has not stopped theorists from devising endless principals and guidelines for combining color in order to elicit a specific aesthetic response. M. Luckeish categorically stated that combinations of red, yellow and blue; yellow-red, green and purple; green-yellow, purple and purple-blue should always be considered good. He goes on to recommend the following color combinations to commercial printers:

Harmonious Hues for Printing on Colored Paper

PAPER	COMBINATIONS OF INKS
Black	Deep Red, Gold and White, Light Blue and Silver.
Light Blue	Purple, Dark Blue, Pale Yellow and Yellow-Brown.
Dark Blue	Light Blue and White, Green and Yellow-Red, Deep Red and Gold.
Light Brown	Green, Gray and Lilac, Dark Brown and Silver.
Dark Brown	Yellow-Red, Black and White, Light Drab.
Light Green	Gold, Dark Brown, Yellow-Red, Dark Green.
Dark Green	Gold and White, Black and Light Green.
Light Gray	Dark Blue and Gold, Dark Gray and Red.
Light Red	Dark Green, Blue and White, Olive and Gold.
Deep Red	Dark Green, Yellow-Red and Dark Blue, White and Gold.
Pale Yellow	Red, Light Blue.
White	Emerald Green, Navy Blue, Crimson Red.

While few any longer make these types of absolute assertions as to the effects color has on its audience, the trend to analyze public taste has only grown stronger. An international association known as the Color Marketing Group was founded in 1962 to identify the direction of color and design trends and then interpret this information into salable colors for manufacture. They hold two conferences yearly to keep their forecasts current, taking everything from politics, the environment, the economy and cultural diversity into consideration. Their motto is Color Sells... and the Right Colors Sell Better! With computers now capable of creating huge data banks and the creation of on demand printing services, the ability to target specific groups with the most current of trends has become a reality. Interest in this type of targeted response among advertisers seems to be the wave of the future.

Postcard Color Chart: This Linen postcard published by Fullcolor was to be used by its customers wishing to turn their black & white photographs into cards. The client was to make a list of objects within the photo composition and then assign one of the numbers from the chart to it before mailing it in. It is apparent that the color choices are not based on color theory or the colorants available but on the fashion of the day. The printer could render all these hues with four to five different inks.

As the Internet makes the world grows smaller the symbolic uses of color have grown ever more confused. In its place there seems to be a growing tendency to pay more intention to the universal psychology of color, that is the associations we make from being human rather than through cultural reference. Some shades of blue seem to keep people more focused on the activity at hand as they cause the release of calming chemicals into the brain. Likewise a person surrounded by yellow tends to feel happy feels optimistic because the body releases more serotonin into the brain. Red has long been used on visual warnings to quickly arouse attention, but as this color has been used more and more for marketing purposes it has lost much of its natural ability to excite. We have created a very colorful world for ourselves where hues are brighter and more intense than ever before. The problem with reaching maximum effect is where do we go from here?

High Chroma: This modern photochrome printed in offset lithography uses a standard CYMK pallet but it was used in such a way to render the image with highly saturated colors. The general color saturation of postcards has steadily grown stronger over the years. While this is in part to technical refinements and better colorants, it it largely driven by marketing concerns. Brighter pallets may be more aye catching but only until this convention becomes seen as normal. Already the color on all printed images needs to be heightened to some degree just to appear natural.

MATERIAL COLOR

The term material color is generally used to refer to the colors we experience in the physical world as opposed to the idealized pure hues of light that do not exist outside of theoretical thinking. Here we use the term to specifically address the concerns surrounding the pigments and dyes used in printing inks. Most theoreticians working with color have not considered any of the applications their ideas may have on physical mediums relevant to their work, but we cannot formulate ideas on how postcards incorporated color without knowing something about ink. While the colorants used to print postcards come from centuries of scientific research in chemistry, physics and engineering, they have also been shaped by government standards, availability of pigments, their lightfast qualities and tinting strength, along with cost, and in more recent times by their environmental impact. The resulting inks that printers have but no choice to use bare little resemblance to the idealized primaries needed to make the trimetric printing processes work perfectly. The yellows and blues used for primary colors on postcards have been far too red while the reds have been much too yellow.

While theorists can discuss color in terms of pure imaginary hues, artists, printers, and dyers have always had to work with the physical pigments available to them. To give primary colors a name is nothing more than an abstract endeavor, they had to be matched to something in the real world and that has never remained a constant. In the early 1700’s Le Blon described the perfect subtractive primary magenta as a mixture of carmine, madder lake and vermilion. In 1772 Moses Harris chose straight vermillion, but in 1785 Johann Lambert described the perfect magenta as carmine. Carmine however is a fugitive color so by the late 19th century alizarin crimson had become the primary of choice. Some colors have been totally mismatched, as the ultramarine blue that Charles Winter chose to represent cyan on his color triangle was actually closer to the magenta hue. The CYMK primaries that now dominate offset printing did not come into use until 1934 when a quinacridone red violet became available to better balance out the gamut, but even this pigment is far too yellow and has trouble producing saturated colors when mixed. It may be safe to say that while color theory states that magenta is a critical component of CYMK tricolor printing it has never actually been used. These shifts in preference and suitability also holds true for all the other primaries as well. In the end the mismatching of colors to theory has not been a major concern of printers. Of far more importance is their ability to achieve results that will work to satisfy their audience.

Tricolor: S.M. Prokoudine-Gorsky was a pioneer in tricolor photography, eventually designing his own camera that produced three black & white transparencies each seperately shot through red, green, and blue filters. When projected back through the same filters in lantern shows, a somewhat flawed yet remarkable color image was produced as seen above. He also had tricolor postcards printed from his photos as below, but while he claimed the colors were natural (d’après nature) they did not quite match up due to the limited colors available in printing ink at that time.

To understand the problem of matching hues we must first understand where colorants come from. Since the earliest civilizations the most common colors came directly from the earth. They could be found in a variations ranging from yellow to red to violet, but were usually made up of some type of naturally forming iron compound. These ochers, sienas, and umbers proved to be extremely stable over time, and eventually became a staple of the artist’s pallet. The search for other minerals that could expand the color gamut continued over the centuries but the discoveries of new pigments came slowly. While some were readily available, others like those that could produce rich blues proved to be elusive. Minerals such as lapis lazuli fit the bill but it was relatively rare and its high cost both limited and determined how it would be used. This situation began to change in the 18th century as a better understanding of chemistry came about. This newly acquired scientific knowledge led to the discoveries of cobalt (1742), manganese (1774), and chrome (1797), which would all substantially add to the availability of new colorants.

By the 19th century the Industrial Revolution had taken chemistry into its fold. Many scientists were not only working to advance theoretical knowledge, they were working on practical answers to real world problems. Chemistry up to this point was largely engaged in the study of minerals as the molecular structure of compounds was considered by most too complex an issue to tackle. This would all change dramatically in 1858 because of the independent work done by three scientists, Aleksandr Butlerov, Archibald Couper, and Friedrich August Kekule, which together formed the foundation of organic chemistry. Once the mechanisms behind molecular bonding were understood a whole new range of synthetic colorants were made possible, and by the end of the 19th century over a thousand new colors were being patented each year. While some new synthetic colorants like alizarin were highly welcome and are still used to this day, most others like the red and violet lakes were found to be less than stable either fading or changing color over short periods of time. This proved to be a potential danger to chromolithography, which employed many colors in its production. The more limited pallet required by the tricolor process began to look more appealing because of the few stable inks that were needed. The unreliability of synthetic pigments eventually forced many out of the market place and by the turn of the 20th century growing skepticism had made the inks available for printing far less numerous but much more stable. For many items already produced the damage was done.

Dyes: On this early trade card we can see a saleswoman demonstrating the wide variety of textile dyes available for use at home. In the second half of the 19th century there was an explosion of new cheap synthetic colorants on the market that took what was once reserved for the most wealthy and put it in the hands of ordinary people.

While we have largely concerned ourselves with pigmented colorants because of there use in printing inks, dyes have actually been the larger focus of color seekers over time because of their relation to textiles. The origins of most dyes had traditionally been in organic mater such as the leaves or seeds of plants but this could also include creatures like the squid from which sepia is drawn. By the latter 19th century most dyes were being synthetically manufactured, but this had little effect on the printing trades until they were attracted to the new brighter inexpensive aniline inks that became available in the 1930’s. Being dye based these inks not only had a higher color density, they were easily mixed with various additives such as optical brighteners. As light falls upon this enhanced dye it excites the electrons within it and the color that emerges reflects back more light energy to the eye than the amount that originally went in. The results are unusually bright colors that may not be natural but were found to be quite eye catching. The problem that arose from these brighteners is that the electron stimulation also speeds up the breakdown of molecular structures making this type of ink far more susceptible to fading. Aniline dyes were widely used in the production of linen postcards until the 1950’s when the health hazards that became associated with then forced their removal from the market.

Dye based inks regained their importance with the introduction of digital printing technology. The printers worked best with dye based inks as the heavier pigmented variety tended to clog the delicate spraying mechanisms used in these devices. This type of ink can also be given an electrostatic charge, which is an essential element behind the process of getting ink to adhere on only selected areas of the paper. These new dyes proved safer to use than the old aniline dyes but they suffer even more from the problem of fading. It has only been in recent years that new dye based colorants were introduced claiming to have archival lightfast qualities, but they are yet to be truly time tested. While some digital printers now use seven colors they still all work on the principal of optical blending. This has greatly diminished the need to discover new colorants and more emphasis is now placed on stabilizing them.

PRACTICAL COLOR

We live in a world today where saturated color is everywhere. It is hard to imagine a time when this did not exist but most people of the 19th century lived in a predominantly black & white world. The sudden appearance of great quantities of color printed matter in ushered in by new technology began to change the works by the 1880’s. It revealed a hunger for color that seemed insatiable, and countless researchers and businessmen sought ways to make a profit by feeding these cravings. By the turn of the century postcard production soared to meet this goal.Technology however wasn’t always up to the task of delivering on what was desired. Interest in capitalizing on discoveries also severely hampered the decimation of knowledge. All this would prevent one single method of printing in color to dominate the market, at least at first. Three major paradigms would basically be followed, each evolving out of desires to reproduce fine art work but the way in which each used color over the last century and a half has not remained consistent. The reasons behind these changes cannot be addressed solely by examining the chronology and mechanics of technique. All the theories, ideas, and concepts discussed further above were about more than speculation, they effected the practical ways in which color was used by printers. As the vast majority of postcards that had been printed and continue to be printed today are produced in color, a proper understanding of their foundation will allow us to see that the way they are presented to us is far from arbitrary.

THE PAINTERLY TRADITION OF LOCALIZED COLOR

CHROMOLITHOGRAPHY
One of the major paradigms used in the production of color printing arose directly out of the desire to reproduce paintings, and so color was used in the same manner by matching them as best as possible to the color seen. Though the optical mixing properties of primary colors had been known since the 17th century, no scientific color separation techniques were available in lithography’s early years and in its place multiple hand drawn substrates were used to produce each individual color and tone. In general the color inks used in chromolithography were applied to represent local color in the same manner that paint was applied to a canvas by an artist, and not according to any theory, perhaps even to avoid it. Choices were further determined by the limitations of the technique itself. Ink can only be applied to a litho-stone in an even film, so colors could only print in the same value as that of the ink used; light, dark, and medium tones of the same hue had to be printed separately. The white of the paper could have been used to create optical tones but this would have also effected the saturation of color. Instead little to no paper was left exposed, and if white was needed it too would be printed as a separate color. This meant that a complicated color image might require up to thirty different stones to create. This build up of ink often caused chromolithographs to suffer from looking dull, as light cannot easily pass through all these layers and reflect back off the paper’s white surface to the eye. Most printers did not go to this extreme producing both traditional and photo based chromolithographs with about ten colors. According to the Handbook of Lithography, published in 1904 by David Cummings the most basic pallet for a chromolithograph was:

Pale yellow
Deep Yellow or orange, though it can be replaced with pink printed over a pale yellow.
Pink or rose
Pale blue, which creates a pale green when printed over pale yellow or a pale violet when printed over pink.
Red or crimson, which creates a vermillion when printed over yellow, or a purple when printed over blue.
Black
Dark blue
Brown, which will produce near blacks when printed over dark blue.
Dark grey
Light Grey

Most hues in chromolithography were split into light and dark components for printing to make up for the inability to create optical tone, but some printers went a step further and shifted the hue itself. According to Chevreul the impurities found in all colorants takes away from their ideal saturation and can render them dull when mixed. His solution was to employ two versions of each primary color with a little of the other primaries added to it. In this way each primary would be split into warm and cool versions. So a warm red orange red (red with some yellow) and a cool red violet (red with some blue) would be substituted for a sole red primary, and then each of these hues could be better blended with its other warm or cool primary counterpart to create a more saturated color mixture. While his theory pertained to the actual physical mixing of colorants, especially in relation to textile dyes, these six primaries were sometimes laid down side by side in printing.

Chromolithograph: This fine art reproduction is on heavy paper stock to hold up all the layers of ink printed on it. While rich an nuanced in color the high density of ink creates a poor reflective surface rendering it somewhat dark. These types of cards were still highly prized and sold for much more than the average postcard.

PHOTO-CHROMOLITHOGRAPHY
When the discovery of a method by which a photograph could be transferred to a litho-stone through photomechanical means without the need of a line screen, it revolutionized the medium, at least to a degree. While this technique allowed images to be copied with much more ease and could produce beautiful results, it continued to use color in the same manner of a traditional chromolithograph. These images were created through black & white film and retouchers would add color in with a broad pallet of about ten colors or so. Only now they were rendered through the grainy patterns of a photosensitive asphaltum emulsion rather than through hand drawn dots.

Photo-Chromolithograph: While this image for the most part captures all the nuances one would expect from the photograph it was made from, its coloration remains somewhat strange. Other contemporaneous methods could extract more natural color from a black & white photo with the use of filters but not all saw this as the correct course. While this form of tricolor printing was expensive, so was printing from ten stones or more. Photo-chromolithography was not used to create a more realistic image but a more painterly one for which there was still a wide audience.

Postcards created through photo-chromolithography display a strange dichotomy of the real and unreal. There precision in capturing details and perspective make their photographic origins unmistakable while the color as appealing as it may be does not reflect what we expect from the natural world. There is a natural tendency by artists to skew the relationship of values in the scene they render so that the contrast between highlights and darks are reduced while the differences in middle tone values are enhanced. In this process the flatter tonal range created was often compensated for by heightening chroma. The use of highly saturated colors was not solely the result of technique but of the current construct in which the public at large found the more abstract use of flattened space not only acceptable but also often aesthetically desirable.

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THE LINE AND WASH TRADITION OF TINTING

TINTS
There has been a long tradition in the fine arts of producing drawings with the solid line of the ink pen and anding in more subtle tones with ink washes. This no doubt grew from our natural inclination to understand space by reading contrasting contours. From producing simple black & white images this technique evolved into more varied versions of watercolor painting. High contrast images had long been made through block printing techniques, but the more difficult task of reproducing the subtleties of washes inspired man new processes. One of the earliest uses of color in lithography was that of the tint, that is a hue to which white has been added to lighten its value and reduce its chroma. The most common tints consisted of a solid flat hue, usually of gray or fawn over which an image would be printed in black. The primary goal of this tint was not to add color but to lower contrast creating a more palatable picture. It also usually brought the final printed image closer to the artist’s intentions as the litho-stones that drawings were initially placed on often had a similar value and color range. By scrapping the tinted areas off of the stone highlighted whites could also be created.

Multiple Tints: This early Gruss aus lithograph was printed with multiple tints but all basically different values of the same hue. These types of false color images proved very appealing to the postcard buying public, and at the same time allowed the printer to ignore controversies regarding what was the correct set of primary colors.

While it may seem as if the tinting process had little to do with color, this assumption would be false. If lowering contrast and adding an extra value were the only concern a neutral grey would do nicely all the time. Though grey was employed the more common tints leaned toward a warm hue. It had long been recognized that a color image could be created from only two hues. It is not that anyone could be fooled into thinking they were viewing a picture in full color, but rather that such an image could be understood as being of color through the minds extrapolation of available data. It is the mind after all that creates color, not the ink on the postcard. Soon two then three then more tints were being used to enhance this effect. The tints were usually used as different values of the same hue or at least of harmonized colors. In this way not only were less expensive inks used but this also cut cost by using far fewer inks than needed in chromolithography. Though this tradition dating from the 1830’s was in practice before highly colored chromolithography came into vogue, both methods were actually developed and used side by side through World War One. While vastly different in appearance both methods shared a similar paradigm of choosing hues based on the traditional ways that artists employed color supported by current fashion.

LINE BLOCK
After chromolithography beat out xylography for supremacy in the commercial printing trades, xylography didn’t just disappear; the practitioners just simplified the process to use no more than three colors, red yellow, and blue. When metal line block printing was found to produce similar results for far less money than the wood block technique it was quickly replaced but it still retained the same RYB pallet. Printers tended to stick with what they knew and these colors were all readily available, in lightfast pigments. RYB worked well enough for it was not deployed here to create true optical effects or render a realistic image, just one that could be understood. When the final image need not express natural color almost any pallet could due. The tendency to stick with traditional knowledge had a lot to do with the confusion surrounding issues of color in the late 19th century. Misinterpretations of scientific theories had led to a variety of color models that rarely worked well in practice leaving printers to follow their own judgment. It is interesting to note that most hand colored postcards of the same early period used the traditional pallet to color prints, which was red, green, and blue.

Line Block: Any colors could be used with line block printing but red, yellow, and blue became the most prevalent. They were either put down in small markings that could offer some optical blending, or just used in a bolder graphic style as on this advertising card. This is the same pallet that would become predominant in tricolor printing, and the halftones they were produced from would be printed in line block as well as through lithography.

COLOR TINTING
The tinting method in printing was made possible because it was a familiar convention replicating the look of pen and wash drawings that had been made for centuries. It was the line work representing contours that gave an image its compositional structure while the washes added tonal range. This model had been used in chromolithography through the use of a dark key plate overprinting fields of numerous color dots, but in the 1890’s some printers found ways to simplify the process. If the composition on the key plate was strong enough then the large pallet used in chromolithography could be avoided, three or four colors would be enough. While chromolithography tried to reproduce an image by matching as many hues to the original image as possible, this seemingly intuitive approach was actually a faulty paradigm. There are never enough choices in ink to match all the nuances of reality. What was needed was a system by which a printed image could stimulate the eye’s color receptors the same way as reality did.

Color Tints: When some printers exchanged their monochrome hues for pale colors on their tinted postcards the move was more revolutionary than it seems. monochromes only needed to be appealing to the eye but colors needed to work together in more complex ways. Though red, yellow, blue, and sometimes green were the most common colors used, all choices were based on the varying color models of the day. These types of early postcards were largely replaced by those hybrids that used photographic halftones a the dark key plate instead of line drawing.

On the surface it would seem that the postcards made through color tinting are based on the same model used to make cards tinted in monochromes. The simple monochrome tints may have provided inspiration but there production required an adjusted way of thinking to create. The same dark key was used, only now it was printed over three or four pale colors laid down as dots. This left the question, what were the colors to be used? The most obvious answer was to use primary colors but there was no agreement at this time to what they were. The most common pallet chosen were based on the colors that printers were already most familiar with, the artists primaries of red, yellow, and blue. It is unclear however how much of this was simply based on tradition or on a faulty understanding of color theory. Competing color models could be used since the actual placement of color on an image was still solely determined by the eye and hand of the retoucher. Different sets of primary colors yielded different results but they were all found to be acceptable to the card buying public, personal taste aside.

TINTED HYBRIDS
In the 19th century the printing trades did their best to use the newfound technology of photography to create printed images. It was adapted to intaglio in the form of gravure, to relief printing in the form of line block, and to the planographic methods of collotype and lithography. All of these would come to be used in postcard production and surpass methods of drawing an image by hand. There was still one basic problem; in a world demanding to see more color there was no color film to base these cards on.

Tinted Collotype: The lack of color film to base postcards on led to all sorts of hybrid postcards, but the basic principal was always the same. A dark photographic based key would be printed over a few select hand drawn pale lithographic dots. The variables were the key plate, which could be made through gravure, line block or lithographic halftones, and collotype. The other set of variables were the colors to use, which could be based on different models. This postcard uses red, yellow, and blue, which was a common choice. It was the retoucher more than the pallet that could render an image realistic or mannered.

A solution was found in the same model used for color tinting. The formula remained the same, a retoucher would chose and layout the primary colors in the form of pale tints but instead of a line drawing a black & white photograph would be printed over it as a key. This was often achieved with the aid of halftone screening developed in the 1880’s. The multiple theories on color and the misinterpretation of them led to a variety of primary choices. Red, yellow, and blue were common, but many printers added in green. Sometimes tints of grey and fawn were added in. These tints helped to disguise the halftone dot pattern by lowering the overall contrast in the image and enhanced the illusion of continuous tone. The attempt here here was not to capture true colors but to create a color image that could be interpreted as real. This paradigm worked because of the minds ability to extrapolate an understanding of space through comparative hues even when they don’t match up to reality. More postcards were produced through this hybrid method during the first four decades of the 20th century than by any other means.

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PHOTOCHROME PRINTING BASED ON OPTICAL THEORY

THE TRICOLOR PROCESS
It was only natural that many first looked at the long tradition of fine arts for inspiration for producing color prints, especially since the primary goal was to reproduce paintings and drawings. The introduction of the photographic halftone brought a new fidelity to the printing process that vastly changed the way we look at the world, but for all its structural accuracy it could not capture the details of color. Where tinted hybrids only addressed this problem cosmetically, the tricolor process would attempt to solve it through science. It began with James Clerk Maxwell’s theory that if three black & white photographs were taken of the same scene, each shot through a red, green, or blue filter and then turned into transparencies they could be made to recombine into a full spectral image by projecting them back through the same three filters. While this method was first applied to the creation of slides for lantern shows, the first tricolor print was made by Ducos du Hauron in 1877. Tricolor printing proved to be a great innovation but it remained much better in theory than it was in practice due to the poor color sensitivity of early photo emulsions. An important change would come in 1881 when Frederick Ives invented a workable panchromatic film emulsion that captured the full spectrum of light. It would take much more time however to perfect it as the values rendered were skewed due to the varying light sensitivity of the different dyes. Even though panchromatic emulsion still produced a black & white photograph, the different color filters that could be placed over a camera’s lens were finally able to accurately separate out different colors of the spectrum within a single scene. When each negative was transferred onto plates and printed in corresponding additive colors, it created the illusion of natural color. Natural color became a term used in printing to differentiate the hues captured through photography from the pallet chosen by a retoucher in a printing house or painted in by a colorist. All images produced through this method were generally referred to as photochromes in their day, though we now only use the term for postcards manufactured after 1934.

Many of the postcards produced through the pure tricolor process are distinctly different from their retouched counterparts in that there seems to be a more natural distribution of color even when the color itself is not totally natural. Overall this fools the eye into thinking it is seeing a more realistic image. At the time this process was introduced the results must have seemed extraordinary for there is a tendency to believe that we observe more realistic images when the convention that presents it to us is changed. In any case the pallet remained a problem. The RGB colors may have been fine when used as additive primaries for projected lantern shows where color mixing takes place solely in the retina of the eye, but this color choice proved troublesome when placed on printed postcards. Red and blue in printed form are relatively dark, which compromises their ability to optically blend. All three colors will also loose chroma if overlapped, as there is no shared reflectance.

Tricolor Process: The postcards produced from tricolor printing are not always so easy to distinguish from their latter process printed counterparts in part because one pallet evolved into the next. Both produce a good range of bright and subtle color but with a different gamut. Because red, yellow, and blue were the predominant colors used in this process and they print relatively dark, they tend to pop out when used alone or create a strong color cast even when carefully blended.

While the premise behind substituting the RGB pallet with three subtractive primaries for tricolor printing had been known since the late 1800’s there were no inks available at this time that properly matched these colors. Those printers producing tricolor prints usually ended up working with the traditional artist primaries of red, yellow, and blue. After the turn of the 20th century as new synthetic pigments became available and most colorants became more highly saturated, printers began shifting the inks they used to lighter varieties that moved closer to the CYM mix. There are some early postcards that were printed with cyan, yellow, and magenta, but these are so rare that the stability of these colorants must be taken into question.

With most printers substituting an RYB pallet for CYM or even RGB colors the scientific principals behind tricolor printing became distorted. When it failed to produce an image in natural color, printers compensated with heavy retouching. These types of manipulated tricolor postcards were printed in great numbers into the 1930’s. The choice of RYB primaries may have not been able to reproduce color in a realistic manner but it could produce richly colored pictures. This made it suitable for printing artist drawn cards and it was largely employed for this work. In this role the RYB pallet can even be preferable to the CYMK mix but this choice is very subjective.

PROCESS PRINTING
By 1934 there had been enough improvements in the manufacture colorants for tricolor printing to turn into process printing utilizing the subtractive CYM primaries. It must be realized however that the inks used to represent cyan, yellow, and magenta were only close enough to use and are not the actual hues needed to make subtractive color principals work perfectly. When printing from plates the ink chosen cannot be the same color as the filter used to create it for inks absorb (subtract) color in the same manner that filters do so the complimentary is chosen instead. Ink that absorbs red reflects back blue and green, which creates cyan in the eye. When blue is absorbed green and red reflect back to form yellow, and the absorption of green reflects red and blue creating magenta. Thus when red, green, or blue needs to be subtracted from the additive color mix its complimentary is printed for cyan will absorb red, yellow will absorb blue, and magenta will absorb green. To create the additive primaries needed to stimulate the eye a combination of two subtractive primaries are printed. As cyan and magenta will absorb their complimentary red and green the color blue is reflected back to the eye. In this same way cyan and yellow make green, magenta and yellow make red. Because a CYM Pallet will print fairly light it has much more reflectivity and will also produce orange green and violet when overprinted. When these secondary colors are received by the eye as an additive mixture, they will average out to simulate the full spectrum.

Blue: If an ink absorbs (subtracts) red light it will reflect back the combination of blue and green, which appears as cyan. If an ink absorbs green light it will reflect back red and blue, which appears as magenta. If an equal amount of cyan and magenta dots are printed next to each other, their reflectance will combine in the eye to make them appear as blue. By following this model all RGB colors can be created by only printing CYM hues.

The deep blue that was printed over a dark red with a yellow in tricolor printing may have not rendered a true black but it did produce a very dark tone that was adequate for most postcards. When the switch was made to process colors the combination of cyan, yellow, and magenta should have produce black but their lighter printed values caused them to merge into a muddy grey instead. To solve this problem an actual black had to be added to create a full range of tonal values. Thus the process colors of CYM became CYMK with K added for key (representing black so not to confuse it with blue). While CYMK was to become the industry standard it was not totally accepted for a long period. Black had already often been added to the tricolor mix of RYB and cards manufactured through process printing were sometimes made without any black added well into the 1940’s.

Process Print: This German made continental card was printed in lithography through process printing. While the pictorial space has all the resemblance to a modern photochrome the color is somewhat flat. While the card is not dated it was probably manufactured in the interim period between the time process colors were invented and when color separation from Kodachrome film became possible. While it appears that the printed color here was added in by a retoucher it could also be based on a poorer quality color film.

Early process prints had the ability to render more natural looking colors but they often looked little different than their earlier counterparts printed through the tricolor process because the color in their compositions were still being determined by the hand of a retoucher. While various types of color film had been around since the early 20th century, none proved adequate for use in large-scale commercial printing. Some printers had still used such film to create color separations for printing plates but the results were never good enough for the method to gain widespread acceptance in relation to the cost involved. Many early Linen postcards produced through process printing skirted trimetric principals and added in a fifth color, usually a medium blue or red to brighten the image. Spot printing had always been used when the mixture of a three color pallet was found incapable of producing a desire hue, but this took the process to a new extreme. For many printers the idea of using process printing to render a natural looking image was not even considered; and postcards became ever more mannered in appearance.

Linen Postcard: While this card is far from being as garish as some, this Linen postcard still demonstrates the unreal colors that could be produced by the hand of a retoucher even when used in conjunction with a photo process. While such a look came about in part from the inability to produce natural color, this convention hung around long after this ability was established showing that it was really about style. These types of cards did not disappear until the public’s taste shifted.

This all began to change in 1938 when the new improved Kodachrome transparency film was introduced. With good color separations now possible to make through photomechanical means, process printing was finally able to reach its full potential and would eventually come to dominate the printing industry as the preferred method of color reproduction. The photochrome postcard (Chrome) produced through this method would eliminate all competition. This however did not happen overnight. In the intervening years you could find Linen postcards created in natural color through Kodachrome separations rather than by the usual color choices of a retoucher, while some early photochrome postcards were still being printed with an RYB pallet. While this was partially due to the time it took to perfect photochrome cards, it also represented the conflict between two visual conventions. As dull as some early photochromes were, they must have looked refreshing when compared to the highly stylized and saturated pallet often found on Linens. When Linen postcards finally disappeared so did the last vestiges of color place on cards by the human eye.

Old Photochrome: When compared to the retouched Linen cards that came before it, photochromes must have looked exceptionally real. A basic problem of trichromatic printing is that if any one of the three colors used becomes too dominant or weak then the entire color balance can be thrown off. This was not particularly noticeable on earlier cards that were colored through the hand of a retoucher for these cards never looked quite real. When colors began being separated through photomechanical means the goal was set higher and anything less than perfection was highly noticeable. The more that color has improved over the last decades the worse these old photochromes look. Scenes with exaggerated color always helped disguise this problem but cards such as this one fail to capture a real sense of place.

While the emphasis in producing photochomes has always been on rendering natural color, that is color based directly from a photograph, there is no golden standard to what natural colors film needs to match. The earliest such images were made as tricolor prints through filtered black & white photo plates. The introduction of early colored film such as Autochrome in 1907 made the mechanics of this process much easier but did not improve on the accuracy of the color captured very much. The dramatic improvements achieved through using Kodachrome film would give postcards a much more realistic look, but this should not be confused with what is actually real. All films are dye based but they do not all use the same dyes. As the markets in different regions of the world came to be dominated by different corporations, the look of the postcards produced there began to look different from one another depending on which brand of film was most widely used.

Russian Photochrome: Many people assume that modern photochromes (chromes) are based on Kodachrome film, but they can be made from any type of transparency or even positive print film. While modern postcard production in the United States was dominated by the Kodachrome process, similar cards in the Soviet Union were based on the Agfa process as seen in the Russian postcard above. Each type of film offered its own unique range of hues depending on the dyes used to manufacture it.

Even though photochromes have dominated postcard production since the 1950’s they have been far from perfect in delivering natural color. They seemed more real at first because they ushered in a new visual convention. Looking back many of these photochromes suffer from extreme color shifts and they can seem wildly distorted. Their continued use has had more to do with their expediency of production than with the results they offered. The most basic problem with all models utilizing primary colors is that they deal with hues as abstract concepts rather than anything that exists in the real world. Spectral colors may be categorized to make common distinctions but they do not follow strict scientific principals for nowhere do they exist in pure wavelengths uncontaminated by each other. We cannot produce them in physical form for the perception of all colorants is based on their chemical makeup, which never reflect a pure color to the eye.

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DIGITAL PRINTING

Digital technology poses a problem of definition across a wide expansion of processes. Changing technology up to this point has usually just pushed an existing process further along, but now printed works that continue to look familiar to the eye are produced through unprecedented means. While this is probably the greatest revolution since the birth of photography, it is still too new and ever changing to put this brand new paradigm into perspective. With the aid of computers our current ability to study both light and the mind in a much more detailed manner has led to the dismissal of many long established ideas about color. Some of these older theories had been suspect for some time but there was no adequate model to replace them with. Today’s color imaging systems no longer use the concept of primary hues to design a pallet; they are based on a true study of the relationships between the colors we actually perceive. This paradigm shift from working with color as a conceptual exercise to the means by which we experience it has changed the way we use ink to print with. Pallet is now determined by the final outcome desired, not by theory.

With the expansion of postcards into the e-card format the color choices that are made have to translate across divergent media more than ever before. Modern color models have been devised to deal with both the printing of color and for use as light in our world of electronic display. Since 1976 much of this is based on Trichromatic Colorimetry where color models are taken from actual electronic measurements of spectral emissions. This has allowed the comparison of colors to be a standardized so that automated color matching can take place within all digital technology regardless of medium.

Modern Photochrome: With modern digital technology applied to the newest offset lithography techniques that use an expanded pallet we are now capable of producing postcards with nearly any gamut we might wish for. While the look of a true natural color image is now at hand public taste is demanding something bolder. In many ways postcards are now as mannered as they were a century ago despite all the knowledge we gained.

On a practical level the pallet used in printing has once again increased in size. Color inkjet printers have expanded the CYMK mix into seven colors to represent addition values that are capable of creating smoother tonal transitions. Commercial printers are using newer systems that can accommodate those colors such as saturated oranges, violets, blues and yellow greens not possible to produce through the CYMK mix alone. The ability to print smaller dots that are no longer confined to line screen halftone patterns have also opened up a whole new range in ways that color can be optically mixed. For the first time we are closer to getting what we want from color rather than being subject to its limitations. What we want of course is still subject to the vagrancy's of taste. It is curious to note that when photochromes outpaced Linen postcards in popularity it was at least in part due to their ability to render more natural colors than found on their exaggerated predecessors. Today when we have the ability to render natural color better than ever the trend is to exaggerate color to gain attention. Perhaps the idea that we have been striving to replicate the world in a more truthful way is not what we have been doing at all.

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SUMMARY

While the exact mechanics behind color vision is still open to debate we have come a long way to understanding it. We do know that the cone shaped neural receptors in the retina of our eyes are only capable of the outright sensing the greenish yellow, green, and blue violet range of the electromagnetic spectrum but that they can create the perception of a multitude of colors by proportionally balancing this stimulus with the oppenent colors they do not immediately register. This ability of the mind to extrapolate over a million colors from such a more limited amount of stimuli is the foundation for why we can understand printed images such as postcards printed in three or sometimes even in two hues. It also explains why any set of colors can be made to work as primaries even when their mixtures produce different gamuts.

The old artist primaries (RYB) where not originally formulated on any scientific principals. They came about in part due to the limited number of pigments once available combined with their ability to work together. They do not actually function as the principals of primary colors dictate but they work well enough because of the minds ability to extrapolate. This is why their use did not disappear in the face of scientific reasoning and came to cloud scientific thought for well over a century. Scientist and layman alike were reluctant to give up the traditions they were familiar with. The latter additive primaries (RGB) and subtractive primaries (CYM) were based on scientific principals but they could never really be matched to the colors available as printing ink. Since all color models were a compromise, all were able to be equally used to produce postcards the public was willing to buy regardless of the confusion regarding primaries.

Before color photography, when color separations were made by the eye and hand of a retoucher, any model seemed to make due, especially on artist drawn cards where an imprecise color match would go unnoticed. It was only in the pursuit of rendering natural color did these systems become more refined and uniform. Digital technology has allowed us to explore the manner in which our vision reacts with light with much more precision, which in turn has improved printing technology. Despite the importance of our newfound ability to render images in natural color, it is only sometimes used in the production of postcards. It seems that most of us are looking for something we like, not what is real. This more than anything else tells us that postcards were rarely about mere visual reproduction that their true appeal lay in their function as art. In the 1940’s when the publishers of Linen cards and photochromes were fighting it out for market supremacy many though that the new ’Chromes were just a fad. Linens lost this battle but we have since come to see that the concept of natural color has not become the final victor but just one style of rendering among many that is subject to public taste. It seems that our understanding of color and information theory has just given us more tools to use, but this use will always be a balance between production costs and public demand even if we ever definitively discover how vision actually works.