Color

Toward the beginning of The Wizard of Oz (1939), as she discovers that her house has landed on the Wicked Witch of the East, the heroine Dorothy (Judy Garland) dons a pair of ruby slippers. Sparkling and unforgettable in their redness, these shoes constitute the center of an important filmic moment: not only do they signal the beginning of the Technicolor era in perhaps the most popular film of all time, they also remain for viewers of all ages among the most memorable objects in twentieth-century screen history. Perhaps their centrality in pop iconography stems from the superior redness of Technicolor red—a red more elusive and more beckoning, more jewel-like and of a denser and greater purity than any other red we can see on the screen, and indeed more saturated and intense than reds we can see in everyday life.

To appreciate the long struggle to infuse color into moving images, one must first understand that in some respects the human eye is more sensitive to color than is film, and that in some respects film is more discerning than the human eye. The subtlest gradations of color and variations in saturation and hue that characterize objects are often beyond what film can record. But at the same time film does record, and intensively, the color temperature of illumination falling on those objects: the characteristic blue of daylight, for example, or the yellow of tungsten light, in either case something that we do not typically perceive with our eyes. Effecting color cinematography has therefore never been an easy task. Color in special effects cinematography is a persistent and vexing problem, especially in the combinations of positive and negative prints used in matte and rear-projection work. But the ability to infuse consistent color into the moving image has itself posed challenges throughout the history of the medium.

TINTING, TONING, AND
EARLY COLOR SYSTEMS

Coloration of moving images goes back to Athanasius Kircher's projection system of 1646, in which sunlight reflected against painted mirrors cast an image on a wall. This was a harbinger of many of the early efforts at tinting films in the late nineteenth and early twentieth centuries. In tinting, color was applied by hand to individual frames of a film; in toning, entire shots were bathed in a colored solution. The French company Pathé used a stencil process for hand-tinting, which reduced the variability that was characteristic of American tinted films; prints rented from Pathé tended to be more similar to each other than those rented from, say, Edison. Two of the films on the first program at Koster and Bial's Music Hall in New York on 23 April 1896, made use of hand-tinted color. The impresario Siegmund Lubin (1851–1923) premiered mono-tinting around 1904, offering films in which various scenes had been tinted different colors; this same technique, used within the context of a narrative strategy, characterized D. W. Griffith's The Lonedale Operator (D. W. Griffith, 1911), where blue and red cast shots were alternated with untinted black-and-white to striking effect.

Hand-tinting can be found in The Great Train Robbery (1903), the most celebrated moment being the reddish gun blast we see when the principal robber fires his gun into the camera. (Depending on the whim of the entrepreneur who rented one of two different versions for showing at his nickelodeon, this shot could have been seen either at the beginning or at the end of the film.) Alfred Hitchcock (1899–1980) pays homage to that moment in the tinted gunshot at the finale of Spellbound (1945), a film otherwise shot in black and white. Numerous examples of hand-tinted color earlier in The Great Train Robbery include the acidic yellow explosion of the strong-box on the train; the yellow marks made by dancers as their shoes touch the floor; the lavender cloak of the stationmaster's daughter; and the orange explosions of gunfire that are produced by the advancing posse riding toward the camera as they pursue the robbers through the woods. In this film, color has a punctuating effect, enhancing certain moments or features of moments and making them seem hyperreal, exceptionally vivid, penetrating.

Through toning, one obtains a wash of color in a black-and-white image. In Un homme et une femme (A Man and a Woman, Claude Lelouch, 1966), various black-and-white scenes are colored in this way, one royal blue, one burnt tangerine orange, one sepia. Much of the narrative unfolds in high-contrast black and white (a car ride from Normandy to Paris in the rain, for example, in which the couple, lost in thought about one another, hear on the background radio that "a man and a woman have been killed" in an automobile accident), with these tinted scenes interposed to suggest the subjective, even transcendental, emotional filter through which the two lovers experience their reality together. For other scenes involving memory, untoned color film was shot and slightly over-exposed to wash out the color. The filmmaker's desire to mix directly seen action with remembered action and emotionally desired action determines his use of both the presence and absence, and the type, of color.

One of the earliest additive color systems was Kinemacolor, developed in 1906 by G. A. Smith (1864–1959). Successive frames of the film were tinted alternately red-orange or green-blue, then finally projected through a rotating double-color filter at thirty-two frames per second. Through persistence of vision the eye of the spectator conjured the color onscreen, but not without developing eyestrain and seeing color migrating across the screen from scene to scene. In 1912 two students at the Massachusetts Institute of Technology, Herbert Kalmus (1881–1963) and Daniel Comstock, went into partnership with W. Burton Wescott (along with Kalmus's wife, the former Natalie Dunfee [1878–1965]). Kalmus, Comstock, and Wescott wanted to go beyond tinting or toning black-and-white frames, and beyond the crude filtration system of Kinemacolor, to develop a viable independent color process for film. The company called Technicolor was born in 1915, and two years later premiered the first "color film," The Gulf Between (1917). A camera was designed that would take duplicate frames of every image, one through a green filter and one through a red filter. Whereas the Kinemacolor process had projected these different frames sequentially, Kalmus and Comstock developed a pair of identical black-and-white release prints that could be projected simultaneously through different filters with the images combined by means of a prism.

By 1922 Kalmus and Comstock had moved on to Technicolor Process No. 2: rather than adding the color through projection, it would be recorded for the first time as information coded directly on the film, in this case, on black-and-white film that was filtered during shooting. Two color records were made on filtered black-and-white stock, red and green-blue, each showing through highlights and shadows the relative amount of the respective color in the photographed scene. These were transferred to what came to be known as a color matrix, a strip of film half as thick as normal film and coated with a gelatin that could harden. The hardened gelatin had something of the quality of a rubber stamp, with intensively colored areas showing up as troughs and lighter areas as peaks. Each record having been imprinted onto its matrix and the two matrices having hardened, the red and green-blue matrices were dyed either green-blue or red respectively and cemented together for projection. The first feature to exhibit this process was The Toll of the Sea (1922), followed by The Ten Commandments (Cecil B. DeMille, 1923). Before the process was superseded in 1927, twenty-four feature films were released, shot all or in part in Technicolor Process No. 2.

Process No. 3 improved on the method by using the two color matrices not for direct projection but as the basis for printing onto blank stock. In a machine that impressed the dyed matrix against the blank stock between pressurized rollers, the stock became colored after it was passed through twice, once for each matrix. This process of pressing dye against a blank, receptive stock is called imbibation. Process No. 3, conceived in 1928, became the basis for all of what Technicolor achieved from that time until, for some years beginning in the 1970s, it went out of business (the company later revived). Between 1928 and 1929, thirty-one silent or part-talkie films were made through this process, culminating in Warner Bros.' The Show of Shows (1929); forty-nine color talkies were made between 1929 and 1933, ending with Warner Bros.' Mystery of the Wax Museum (1933).

THREE-STRIP TECHNICOLOR

Through connection with Walt Disney (1901–1966), the three-strip Technicolor process that achieved worldwide fame was brought into being. In a process of "successive exposure," animated material was filmed three times through a red, a blue, and a green filter to produce three black-and-white records that were transposed onto three dyeable matrices. Important here was the use of panchromatic—rather than orthochromatic—black-and-white stock: this responded not only to blue and violet light but also to yellow and red light, thus making possible a fulsome and richly accurate record in black and white of the full range of color in a scene. The blank stock was rolled three times in order to pick up the three vital color dyes—magenta, cyan, and yellow. In this way twenty-six animated features were made between Flowers and Trees (1932) and Robin Hood (1973), including all of the most celebrated full-length Disney features: Snow White and the Seven Dwarfs (1937), Fantasia (1940), Pinocchio (1940), Dumbo (1941), Bambi (1942), Cinderella (1950), Alice in Wonderland (1951), and Peter Pan (1953).

HERBERT THOMAS KALMUS
b. Boston, Massachusetts, 9 November 1881, d. 11 July 1963

Herbert Thomas Kalmus, principal founder of Technicolor, remains one of the most important contributors to the development of motion pictures. Like only a handful of technological innovators, Kalmus deftly blended a shrewd but charming business sense—which was instrumental in attracting investors and Hollywood studios—with a probing and imaginative scientific mind. Were it not for Kalmus's persistence and vision, not to mention his business acumen, the industry-wide adoption of three-color processes for shooting films in full color would have occurred indefinitely later. The man who became synonymous with Technicolor thus changed the course of film history. Like synchronized sound, color required an industrial overhaul of every phase of movie making, but what tested the resolve of Dr. Kalmus and his company was the need to enhance and improve the process until Hollywood would start making the switch to color movies—a period lasting some three decades.

Orphaned at a young age, Kalmus worked his way into and through Massachusetts Institute of Technology (then called Boston Tech). There he met the school's only other physics major at the time, Daniel F. Comstock, who would become his business partner. After graduating from M.I.T. and then, in 1906, receiving their doctorates in Europe, the pair of young physicists returned to the United States. Between 1910 and 1915, Kalmus worked at Queen's University in Canada, where he performed his first research on the Technicolor process. In 1912, when they teamed up with W. Burton Wescott, an "engineering genius" in Kalmus's estimation, the trio started a patent company called Kalmus, Comstock, and Wescott (KCW). The young firm made several profitable inventions, but it was not long before Technicolor was its exclusive focus.

As early as 1915 KCW took out patents (mainly on special equipment for color cinematography and projection) for the first Technicolor process. Within two years they were shooting their first color film, The Gulf Between (1917), with a special Technicolor camera that used a beam splitter to simultaneously expose two different strips of film, one sensitive to the green spectrum and the other to the red spectrum. However, the procedure was imperfect and costly, and it was not until the fourth Technicolor process, patented in 1935, that they were successful. The first of Technicolor's three-strip processes, it was used with enormous success in films such as The Wizard of Oz (1939) and Gone with the Wind (1939). Later, after inventing a mono-pack color process, which could be shot with a standard one-strip, black-and-white motion picture camera, Technicolor briefly cornered the market and initiated the industry's full conversion to color.

Of the three original founders, Kalmus was the only one to see Technicolor through to its most successful and profitable period, in spite of a series of highly publicized and scrutinized lawsuits by his ex-wife, Natalie Kalmus, who held a stake in Technicolor for decades.

FURTHER READING

Cardiff, Jack. The Magic Hour. London, Boston: Faber and Faber, 1996.

Neale, Stephen. Cinema and Technology: Image, Sound, Colour. Bloomington: Indiana University Press, 1985.

Drew Todd

Technicolor features were remarkable for the sharpness and saturation of the colors to be seen. No other process before or since has matched the quality of the Technicolor red, for example, or has produced a screen black so intense. There is a potent sense of color contrast that produces at once clarity, saturation, depth and roundness of color, and vivacity. This effect is largely due to the quality of the long-lasting dyes that are used

in the imbibation process. In general in color photography, color effects fade when film is projected repeatedly, or exposed to heat or the air, and the most long-lasting and saturated color effects are possible through dye-transfer printing. Whereas animated cels, themselves quite motionless, could be photographed any number of times through different filters to produce film color, in order to achieve this startling screen effect with live action a new technology was required: actors moving on a soundstage presented a new challenge altogether, as became evident in the first three-strip production, Becky Sharp (Rouben Mamoulian, 1935). With this film, produced by Technicolor shareholder John Hay (Jock) Whitney (1904–1982), it became clear how the increased production cost of Technicolor could make sense in the overall economy of filmmaking. In Becky Sharp the color blue, not present in the earlier two-strip process, was emphasized. Technicolor's investment in motion pictures was literally the startling and enriched color effect it could contribute to the process, luring audiences to see something they could not see anywhere else.

The film historian Tino Balio notes that to guarantee this effect, because Kalmus refused to trust studio cameramen and lab facilities, the company's contract with producers stipulated that they rent camera equipment as well as film stock from Technicolor, arrange all processing through the company, and use a company-approved cinematographer. A special color consultant had to be on set at all times, to consult with, and advise, the director and the cinematographer as to lighting, set design, costuming, and makeup so as to achieve the best possible color effects. Natalie Kalmus favored the dark background as ideal for showing facial tones clearly and strongly. In 1937 Max Factor developed a special makeup called Pan-Cake, yellow in hue, that would allow skin tones to be recorded "naturally" under the intense (bluish) studio light required for the process. All cameras, lenses, and stock had to be procured directly from Technicolor, which took responsibility for the upkeep and repair of the camera and the quality of the black-and-white stock used on set and the matrix and printing stock used in its own lab. A minimum print order of three hundred was typical in the Technicolor contract. Through a process called color timing, it was possible in the laboratory to achieve the precise printing of each black-and-white color record so that once it was dyed and printed an exact coloration could be obtained, shot by shot.

The three-strip Technicolor camera, a monstrous, noisy, and bulky machine that required special dollies and cranes, as well as a "blimp" to cover and dampen it acoustically, was originally designed by J. Arthur Ball, George Mitchell, and Henry Prouch. The camera was fed with three threaded black-and-white reels of negative stock—with a very low speed rating, thus requiring immense quantities of studio light—and admitted light through a gold-coated prism that would split the incoming beam into two equal parts. One beam was sent directly to the back of the camera, where it was recorded through a green filter on a single piece of film. Because of the directness of the passage of this beam, and the fact that green filtering always produces the highest-quality contrast, this "green record" was the one used later on to control for the contrast of the entire picture. The remaining light went at 90 degrees toward two strips of film laid back to back, hitting them after passing through a magenta filter (that would allow blue and red light to go through). The "blue record" was made on top and the "red record" at the back. As time went by, the coating of the prism was changed to permit more and more specifically controlled light to reach each piece of film. The three black-and-white film records were subsequently converted to matrices, which were dyed and printed directly onto a piece of blank stock. Well over one thousand features were made in the three-strip Technicolor process from 1934 onward.

COLOR STOCK

No consistent and true color film stock was available until the end of the 1940s, at which time Kodak introduced its Eastmancolor negative stock. With this product, a number of changes became possible in shooting technique, all of which decreased production cost and made spontaneity and mobility in shooting easier. Here the color was not printed in by dye-transfer, but was contained in an emulsion layer on the original negative stock in the form of dye couplers—chemicals that would be changed by the effect of color illumination. Eastmancolor prints were actually somewhat sharper than Technicolor prints, although the naked eye of the viewer did not detect this because of the "sharpening" effect of the color saturation of Technicolor. Cameras could now be considerably lighter and more mobile. Intense illumination was no longer required for shooting, and, in fact, it was possible to shoot color film in available light—as, famously, Néstor Almendros (1930–1992) did for Eric Rohmer (b. 1920) in Le Genou de Claire (Claire's Knee, 1970); much of the extensive constraint as to costuming, makeup, set decoration, and lighting was removed. Unless it was exposed meticulously, however, and processed with great care, Eastmancolor gave inferior screen effects when compared with Technicolor. So poor were some of the results, owing to the money-saving casualness of treatment provided at the studios, that Kodak insisted the studios apply their own name to the process, and thus were born Pathécolor and WarnerColor. Most important for later film audiences, films shot in Eastmancolor (principally in the 1970s and onward) had a very short shelf life. Negatives were good for only around one hundred prints, and because these final prints were themselves degraded through projection their color was substantially lost. But the process was cheap, and thus attractive to producers who had to contend with higher above-the-line costs for stars and scripts. By contrast, the original Technicolor negatives were black and white and were used only for the production of the printing matrices. Thus, new Technicolor prints made from original negatives remain as crisp and brilliant as they were originally. DVDs printed from original Eastmancolor negatives make it possible to see films digitally that have, in their original form, hopelessly degraded.

THE COLOR EFFECT AND COLOR FILM

By the late 1940s Hollywood was confronting several threats to box office sales: the new medium of television, the effects of the Paramount Decree (the popular name for the Supreme Court antitrust decision that led to the dismantling of the studio system), and the House Un-American Activities Committee hearings into an alleged Communist Party presence in Hollywood. Technicolor and other color technologies became vital selling tools, providing viewers with an optical experience that could not be obtained outside the movie theater. Beyond Dorothy's ruby slippers, one can name countless unforgettable objects of color on the screen: Gene Kelly's red carnation in the ballet in An American in Paris (1951) or the one Gael García Bernal grips in his teeth in Pedro Almodóvar's Bad Education (La Mala Educación, 2004); Ripley's orange cat in Alien (1979); the sunset into which Luke Skywalker gazes as he resolves to go forward to meet his future in Star Wars (1977); the yellow fumes coming out of the smokestack at the end of Antonioni's Il Deserto rosso (The Red Desert, 1964); the Emerald City; Peter O'Toole's famous blue eyes in Lawrence of Arabia (1962); the purple flowers Rock Hudson buys for Jane Wyman in Magnificent Obsession (Douglas Sirk, 1954), or the brilliant fuchsia walls of the Miami Beach hotel in Written on the Wind (Sirk, 1956); the pink panther; the Blue Meanies. Color also described people, scenes, and moments as objects: the swarthy brownness of Natalie Wood when pallid John Wayne and not-so-pallid Jeffrey Hunter discover her at the end of The Searchers (1956); avocado green Jim Carrey in The Mask (1994); the mauve atmosphere of Wyoming in Shane (1953); the subtle and rich palette of browns and beiges that describe the desert love dream of Zabriskie Point (1970); the intoxicating green apartment in Bertolucci's The Dreamers (2003).

Although the history of cinema has been inscribed by numerous exceptionally talented cinematographers (working with brilliant designers, costume designers, makeup artists, and lighting technicians—all of whom necessarily collaborate in the production of screen color), nevertheless the decision to use a color stock for the purpose of shooting a motion picture does not guarantee that the color onscreen will play a significant role in the film. A color film can fail to function in, even if it is shot in, color. Color film stock guarantees that there will be color onscreen, technically speaking, but nothing more. When we come away from the film and think back on it, very often we remember no object or scene or point of concentration in which color is the determining variable. In Blood Simple (Joel and Ethan Coen, 1984), for example, there is one moment when a large amount of viscous and extremely dark red—almost plum red—blood oozes across a floor. That is a true color moment in a color film, but it is the only such moment in that film, all of which is shot in color. Nicholas Ray (1911–1979) was an architect before he was a filmmaker, a man who saw the world as form-in-space; in Party Girl (1958), for example, he dresses Cyd Charisse in a spangling red dress and has her extend herself anxiously but beautifully along the length of an orange velvet sofa. The tension between the color values of that dress and that sofa creates an electricity that energizes the entire film.

A similar, albeit considerably more expensive, application of this same process is to be seen in a long sequence in the black-and-white film, Schindler's List (Steven Spielberg, 1993). A little girl in a red overcoat wanders through the streets in the face of an augmenting chain of Nazi atrocity, marching soldiers, and an overall atmosphere of bleak despair. Finally, she is seen dead, her red overcoat a pungent reminder that she was once a discriminable, sovereign person. Here, the effect is obtained through frame-by-frame computerized tinting—photoshopping the coat while leaving all other aspects of the sequence, and the film, in what now appears to be stark and passionless black and white. When a computer process rather than an artist's hand technique is used to color frames, consistency between frames is obtained mechanically and thus a quality of continuous color is achievable. In Pleasantville (1998) computer colorization and optical printing together make possible the gradual infusion of color into specific parts of a black-and-white environment. The effect of mixing color and black and white in that film might appear to reflect what was done in The Wizard of Oz as Dorothy opened the door of her little house and stepped out into a fully Technicolored Oz, but in Wizard a sequence of sepia-tinted black-and-white film was joined to a sequence of full-color film to produce the startling effect.

At the end of Schindler's List, the narrative leaps forward to the present day in Israel, as remaining survivors of the Holocaust saved by Schindler gather in Jerusalem to remember him. This sequence is shot in full color, rendering everything that preceded it as neutral in retrospect as a desiccated historical record, certainly important factually and yet bleached of the thrilling color of "present" reality. In the black and white The Solid Gold Cadillac (1956), a radically different effect is produced by shooting the culminating parade sequence in full color. All through the film a "solid gold Cadillac" has been invoked in the dialogue, but we have been denied the opportunity of seeing it directly; now, at the end, Judy Holliday and Paul Douglas are seen riding in this vehicle while crowds cheer all around. The goldness of the car is made especially intense by virtue of being visible directly in color; it is an especially "golden" golden car, because in comparison to the black and white by means of which we have been learning about it, it is seen now in the relatively "golden"—that is, valuable—medium of Technicolor.

SOME IMPORTANT COLOR FILMS

Notable uses of color in film include Sven Nykvist's (b. 1922) symphony of red and green in Viskningar och rop (Cries and Whispers, Ingmar Bergman, 1972, in Eastmancolor) and the sunset-lit palette Nykvist utilized in What's Eating Gilbert Grape (Lasse Hallström, 1993); Jean-Luc Godard's (b. 1930) primary-colored text blocks as part of the rhythmic design of Weekend (shot by Raoul Coutard in Eastmancolor, 1967); and the effects produced by the cinematographer Gordon Willis (working with designer Mel Bourne, decorators Mario Mazzola and Daniel Robert, costume designer Joel Schumacher, and makeup artist Fern Buchner) for Interiors (Woody Allen, 1978), in which a perfectly coordinated, subdued, even shackled bourgeois environment set out in a range of beige tones—costumes, walls, curtains, vases, complexions, shadows, everything—is suddenly disrupted after a matriarch's suicide by the appearance of the father's new girlfriend, dressed in explosive scarlet.

Les Parapluies de Cherbourg (The Umbrellas of Cherbourg, Jacques Demy, 1964), was shot on Eastmancolor by Jean Rabier (b. 1927), with design by Bernard Evein. The little village of Cherbourg is configured as a grouping of tiny shops and apartments, alleys, corridors, and a garage. In virtually every setting, the walls are decorated with bizarre and supersaturated patterns and designs, often mixing brilliant red and yellow with brilliant lime green, purple, orange, and turquoise. There is a candy-shop quality to the images that perfectly matches the fairytale quality of the story and the lyrical quality of the dialogue, every word of which is sung to orchestral accompaniment. In the final sequence, which takes place in a winter snowfall and at night, red, blue, and yellow framed against the nocturnal blackness are the only colors that remain—as the former lovers discover one another again after many years and realize that their past is irretrievable. The boy, in fact, has become the owner of an Esso station, which is photographed to look like a giant toy garage. For The Ladies Man (Jerry Lewis, 1961), the set design of Ross Bellah and Hal Pereira, decorated by Sam Comer and James Payne, and shot in Technicolor by W. Wallace Kelley, features a giant boardinghouse in which nubile girls dressed by Edith Head in pastel pajamas wake up in variously colored rooms.

The Band Wagon (Vincente Minnelli, 1953) has a number of startling color sequences, in particular Fred Astaire's "Put a Smile on Your Face" dance routine. On a set designed by Preston Ames, Harry Jackson's Technicolor camera shoots a kaleidoscopic arcade with Astaire, in a light gray suit with royal blue socks, dancing his troubles away with a shoeshine man in a green Hawaiian shirt and hot fuchsia socks. In the celebrated "Dancing in the Dark" duet, Astaire and Cyd Charisse, both in elegant white against a vivid green-and-blue background of Central Park at twilight, move to Arthur Schwartz's music as the color of the set—not quite real, not quite fake—suspends and lulls us into a trance of engagement. In a stunning moment we see the horse that has pulled their carriage to this location pausing to drink from a fountain in which the water is sapphire blue—the blue of dreams, of pure wonder.

SEE ALSO Cinematography;Lighting;Technology

FURTHER READING

Balio, Tino. Grand Design: Hollywood as Modern Business Enterprise, 1930–1939. Berkeley: University of California Press, 1995.

Bowser, Eileen. The Transformation of Cinema: 1907–1915. Berkeley: University of California Press, 1990.

Buscombe, Edward. "Sound and Color." In Movies and Methods: An Anthology, Vol. 2, edited by Bill Nichols, 83–91. Berkeley: University of California Press, 1985.

Fielding, Raymond. The Technique of Special Effects Cinematography. New York: Hastings House, 1968.

Gunning, Tom. "Systematizing the Electric Message: Narrative Form, Gender, and Modernity in The Lonedale Operator." In American Cinema's Transitional Era: Audiences, Institutions, Practices, edited by Charlie Keil and Shelley Stamp, 15–50. Berkeley: University of California Press, 2004.

Haines, Richard W. Technicolor Movies: The History of Dye Transfer Printing. Jefferson, NC: McFarland, 1993.

Musser, Charles. The Emergence of Cinema: The American Screen to 1907. Berkeley: University of California Press, 1994.

Winston, Brian. "A Whole Technology of Dyeing." Daedalus 114, no. 4 (Fall 1985): 105–123.

Murray Pomerance

Color

Light and color

Rainbows

Refraction: the bending of light

Diffraction and interference

Transparent, translucent, and opaque

Mixing colors

Color vision

Color blindness

Color effects in nature

Characteristics of color

Mixing colorants, pigments, dyes, and printing

Additive and subtractive

Primary, secondary, and complementary

Colors are everywhere

Resources

Several scientific disciplines are involved in explaining the phenomenon of color. The physics of light, the chemistry of colorants, and the psychology and physiology of human emotion are all related to our experience of color.

Light and color

Colors are an aspect of light; strictly speaking, color is the form in which human beings and other color-perceiving animals detect differences in the wavelength of visible light. Thus, an object appears colored because of the way it interacts with light.

When we talk about light, we usually mean white light. When white light passes through a prism (a triangular transparent object) something very exciting happens. The colors that make up white light disperse into what human beings tend to perceive as seven bands of color. These bands of color are called the visible spectrum (from the Latin word for image). When a second prism is placed in just the right position in front of the bands of this spectrum, they merge to form invisible white light again. Isaac Newton (1642–1727) was a scientist who conducted research on the Sun, light, and color. Through his experiments with prisms, he was the first to demonstrate that white light is composed of the colors of the spectrum. White light is simply a mixture of colored lights.

Seven colors constitute white light: red, orange, yellow, green, blue, indigo, and violet. Students in school often memorize acronyms like ROY G BIV, to remember the seven colors of the spectrum and their order. Sometimes blue and indigo are treated as one color. In any spectrum the bands of color are always organized in this order from left to right. There are also wavelengths outside the visible spectrum, such as ultraviolet.

Rainbows

A rainbow is a spectrum naturally produced by millions of raindrops acting as prisms. One can often see rainbows after summer showers, early in the morning, or late in the afternoon, when the sun is low. Raindrops act as tiny prisms and disperse the white sunlight into the form of a large arch composed of visible colors. To see a rainbow, one must be located between the Sun and raindrops forming an arc in the sky. When sunlight enters the raindrops at the proper angle, it is refracted by the raindrops, then reflected back at an angle. This creates a rainbow. Artificial rainbows can be produced by spraying small droplets of water from a garden hose with one’s back to the sun.

Refraction: the bending of light

Refraction is the bending of a light ray as it passes at an angle from one transparent medium to another. As a beam of light enters glass at an angle, it is refracted or bent. The part of the light beam that strikes the glass is slowed down, causing the entire beam to bend. The more sharply the beam bends, the more it is slowed down.

Each color has a different wavelength, and it bends differently from all other colors. Short wavelengths are slowed more sharply upon entering glass from air than are long wavelengths. Red light has the longest wavelength and is bent the least. Violet light has the shortest wavelength and is bent the most. Thus violet light travels more slowly through glass than does any other color.

Like all other wave phenomena, the speed of light depends on the medium through which it travels. As an analogy, think of a wagon that is rolled off a sidewalk onto a lawn at an oblique angle. When the first wheel hits the lawn, it slows down, pulling the wagon toward the grass. The wagon changes direction when one of its wheels rolls off the pavement onto the grass. Similarly, when light passes from a substance of high density into one of low density, its speed increases, and it bends away from its original path. In another example, one finds that the speed and direction of a car will change when it comes upon an uneven surface like a bridge.

Diffraction and interference

Similar colors can be seen in a thin film of oil, in broken glass, and on the vivid wings of butterflies and other insects. Scientists explain this process by the terms, diffraction and interference. Diffraction and refraction both refer to the bending of light. Diffraction is the slight bending of light away from its straight line of travel when it encounters the edge of an object in its path. This bending is so slight that it is scarcely noticeable. The effects of diffraction become noticeable only when light passes through a narrow slit. When light waves pass through a small opening or around a small object, they are bent. They merge from the opening as almost circular, and they bend around the small object and continue as if the object were not there at all. Diffraction is the sorting out of bands of different wavelengths of a beam of light.

When a beam of light passes through a small slit or pin hole, it spreads out to produce an image larger than the size of the hole. The longer waves spread out more than the shorter waves. The rays break up into dark and light bands or into colors of the spectrum. When a ray is diffracted at the edge of an opaque object, or passes through a narrow slit, it can also create interference of one part of a beam with another.

Interference occurs when two light waves from the same source interact with each other. Interference is the reciprocal action of light waves. When two light waves meet, they may reinforce or cancel each other. The phenomenon called diffraction is basically an interference effect. There is no essential difference between the phenomena of interference and diffraction.

Light is a mixture of all colors. One cannot look across a light beam and see light waves, but when light waves are projected on a white screen, one can see light. The idea that different colors interfere at different angles implies that the wavelength of light is associated with its colors. A spectrum can often be seen on the edges of an aquarium, glass, mirrors, chandeliers, or other glass ornaments. These colored edges suggest that different colors are deflected at different angles in the interference pattern.

The color effects of interference also occur when two or more beams originating from the same source interact with each other. When the light waves are in phase, color intensities are reinforced; when they are out of phase, color intensities are reduced.

When light waves passing through two slits are in phase, there is constructive interference, and bright light will result. If the waves arrive at a point on the screen out of phase, the interference will be destructive, and a dark line will result. This explains why bubbles of a nearly colorless soap solution develop brilliant colors before they break. When seen in white light, a soap bubble presents the entire visible range of light, from red to violet. Since the wavelengths differ, the film of soap cannot cancel or reinforce all the colors at once. The colors are reinforced, and they remain visible as the soap film becomes thinner. A rainbow, a drop of oil on water, and soap bubbles are phenomena of light caused by diffraction, refraction, and interference. Colors found in birds such as the blue jay are formed by small air bubbles in its feathers. Bundles of white rays are scattered by suspended particles into their components’ colors. Interference colors seen in soap bubbles and oil on water are visible in the peacock feathers. Colors of the mallard duck are interference colors and are iridescent, meaning they change in hue when seen from different angles. Beetles, dragonflies, and butterflies are as varied as the rainbow and are produced in a number of ways, which are both physical and chemical. Here, the colors are separated by thin films, and they flash and change when seen from different angles.

Light diffraction has the most lustrous colors of mother of pearl. Light is scattered for the blue of the sky which breaks up blue rays of light more readily than red rays.

Transparent, translucent, and opaque

Materials like air, water, and clear glass, which pass visible light with little diminishment, are called transparent. When light encounters transparent materials, almost all of it passes directly through them. Glass, for example, is transparent to all visible light. The color of a transparent object depends on the color of light it transmits. If green light passes through a transparent object, the emerging light is green; similarly if red light passes through a transparent object, the emerging light is red.

Materials like frosted glass and some plastics are called translucent. When light strikes translucent materials, only some of the light passes through them. The light does not pass directly through the materials. It changes direction many times and is scattered as it passes through. Therefore, we cannot see clearly through them; objects on the other side of a translucent object appear fuzzy and unclear. Because translucent objects are semitransparent, some ultraviolet rays can go through them. This is why a person behind a translucent object can get a sunburn on a sunny day.

Most materials are opaque. When light strikes an opaque object none of it passes through. Most of the light is either reflected by the object or absorbed and converted to heat. Materials such as wood, stone, and metals are opaque to visible light.

Mixing colors

What we see as color is the effect of light shining on an object. When white light shines on an object it may be reflected, absorbed, or transmitted. Glass transmits most of the light that comes into contact with it; thus it appears colorless. Snow reflects all of the light and appears white. A black cloth absorbs all light, and so appears black. A red piece of paper reflects red light better than it reflects other colors. Most objects appear colored because their chemical structure absorbs certain wavelengths of light and reflects others.

The sensation of white light is produced through a mixture of all visible colored light. While the entire spectrum is present, the eye deceives us into believing that only white light is present. White light results from the combination of the visible portions of the spectrum. When equal brightnesses of these are combined and projected on a screen, we see white. The screen appears yellow when red and green light alone overlap. The combination of red and blue light produces the bluish-red color of magenta. Green and blue produce the greenish blue color called cyan. Almost any color can be made by overlapping light in three colors and adjusting the brightness of each color.

Color vision

What we call color depends on the effects of light waves on receptors in the eye’s retina. The currently accepted scientific theory is that there are three types of cones in the eye. One of these is sensitive to the short blue light waves; it responds to blue light more than to light of any other color. A second type of cone responds to light from the green part of the spectrum; it is sensitive to medium wavelengths. The third type of light-sensitive cone responds to the longer red light waves. If all three types of cone are stimulated equally our brain interprets the light as white. If blue and red wavelengths enter the eye simultaneously we see magenta. Recent scientific research indicates that the brain is capable of comparing the long wavelengths it receives with the shorter wavelengths. The brain interprets electric signals that it receives from the eyes like a computer.

Nearly 1, 000 years ago, Alhazen, an Arab scholar recognized that vision is caused by the reflection of light from objects into our eyes. He stated that this reflected light forms optical images in the eyes. Alhazen believed that the colors we see in objects depend on both the light striking these objects and on some property of the objects themselves.

Color blindness

Some people are unable to see some colors. This is due to an inherited condition known as color blindness. John Dalton (1766–1844), a British chemist and physicist, was the first to discover color blindness in 1794. He was color blind and could not distinguish red from green. Many color blind people do not realize that they do not distinguish colors accurately. This is potentially dangerous, particularly if they cannot distinguish between the colors of traffic lights or other safety signals. Those people who perceive red as green and green as red are known as red-green color blind. Others are completely color blind; they only see black, gray, and white. It is estimated that 7% of men and 1% of women are born color blind.

Color effects in nature

We often wonder why the sky is blue, the water in the sea or swimming pools is blue or green, and why the sun in the twilight sky looks red. When light advances in a straight line from the sun to Earth, the light is refracted, and its colors are dispersed. The light of the dispersed colors depends on their wavelengths. Generally the sky looks blue because the short blue waves are scattered more than the longer waves of red light. The short waves of violet light (the shortest of all the light waves) disperse more than those of blue light. Yet the eye is less sensitive to violet than to blue. The sky looks red near the horizon because of the specific angle at which the long red wavelengths travel through the atmosphere. Impurities in the air may also make a difference in the colors that we see.

Characteristics of color

There are three main characteristics for understanding variations in color. These are hue, saturation, and intensity or brightness. Hue represents the observable visual difference between two wavelengths of color. Saturation refers to the richness or strength of color. When a beam of red light is projected from the spectrum onto a white screen, the color is seen as saturated. All of the light that comes to the eye from the screen is capable of exciting the sensation of red. If a beam of white light is then projected onto the same spot as the red, the red looks diluted. By varying the intensities of the white and red beams, one can achieve any degree of saturation. In handling pigments, adding white or gray to a hue is equivalent to adding white light. The result is a decrease in saturation.

A brightly colored object is one that reflects or transmits a large portion of the light falling on it, so that it appears brilliant or luminous. The brightness of the resulting color will vary according to the reflecting quality of the object. The greatest amount of light is reflected on a white screen, while a black screen would not reflect any light.

Mixing colorants, pigments, dyes, and printing

Color fills our world with beauty. We delight in the golden yellow leaves of autumn and the beauty of spring flowers. Color can serve as a means of communication, to indicate different teams in sports, or, as in traffic lights, to instruct drivers when to stop and go. Manufacturers, artists, and painters use different methods to produce colors in various objects and materials. The process of mixing colorants, paints, pigments, and dyes is entirely different from the mixing of colored light.

Colorants are chemical substances that give color to such materials as ink, paint, crayons, and chalk. Most colorants consist of fine powders that are mixed with liquids, wax, or other substances that facilitate their application to objects. Dyes dissolve in water. Pigments do not dissolve in water, but they spread through liquids. They are made up of tiny, solid particles, and they do not absorb or reflect specific parts of the spectrum. Pigments reflect a mixture of colors.

When two different colorants are mixed, a third color is produced. When paint with a blue pigment is mixed with paint that has yellow pigments, the resulting paint appears green. When light strikes the surface of this paint, it penetrates the paint layer and hits pigment particles. The blue pigment absorbs most of the light. The same color looks different against different background colors. Each pigment subtracts different wavelengths.

Additive and subtractive

All color is derived from two types of light mixture, an additive and a subtractive process. Both additive and subtractive mixtures are equally important to color design and perception. The additive and subtractive elements are related but different. In a subtractive process, blended colors subtract from white light the colors that they cannot reflect. Subtractive light mixtures occur when there is a mixture of colored light caused by the transmittance of white light. The additive light mixture appears more than the white light.

In a subtractive light mixture, a great many colors can be created by mixing a variety of colors. Mixing colored light produces new colors different from the way colorants are mixed. Mixing colorants results in new colors because each colorant subtracts wavelengths of light. But mixing colored lights produces new colors by adding light of different wavelengths.

Both additive and subtractive mixtures of hues adjacent to each other in the spectrum produce intermediate hues. The additive mixture is slightly saturated or mixed with light, the subtractive mixture is slightly darkened. The complementary pairs mixed subtractively do not give white pigments with additive mixtures.

Additive light mixtures can be used in a number of slide projectors and color filters in order to place different colored light beams on a white screen. In this case, the colored areas of light are added to one another. Subtractive color mixing takes place when a beam of light passes through a colored filter. The filter can be a piece of colored glass or plastic or a liquid that is colored by a dye. The filter absorbs and changes part of the light. Filters and paints absorb certain colors and reflect others.

Subtractive color mixing is the basis of color printing. The color printer applies the colors one at a time. Usually the printer uses three colors: blue, yellow, and red, in addition to black for shading and emphasis. It is quite difficult for a painter to match colors. To produce the resulting colors, trial and error, as well as experimenting with the colors, is essential. It is difficult to know in advance what the resulting color will be.

People who use conventional methods to print books and magazines make colored illustrations by mixing together printing inks. The color is made of a large number of tiny dots of several different colors. The dots are so tiny that the human eye does not see them individually. It sees only the combined effects of all of them taken together. Thus, if half of the tiny dots are blue and half are yellow, the resulting color will appear green.

Dying fabrics is a prehistoric craft. In the past, most dyes were provided solely from plant and animal sources. For example, yellow came from the sap of a tree, from the bark of the birch tree, and onion skins. There were a variety of colors obtained from leaves, fruits, and flowers. In antiquity, the color purple or indigo, derived from plants, was a symbol of aristocracy. In ancient Rome, only the emperor was privileged to wear a purple robe.

Today, many dyes and pigments are made of synthetic material. Thousands of dyes and pigments have since been created from natural coal tar, from natural compounds, and from artificially produced organic chemicals. Modern chemistry is now able to combine various arrangements and thus produce a large variety of color.

The color of a dye is caused by the absorption of light of specific wavelengths. Dyes are made of either natural or synthetic material. Chemical dyes tend to be brighter than natural dyes. In 1991 a metamorphic color system was created in a new line of clothes. The color of these clothes changes with the wearer’s body temperature and environment. This color system could be used in a number of fabrics and designs.

Sometimes white clothes turn yellow from repeated washing. The clothes look yellow because they reflect more blue light than they did before. To improve the color of the faded clothes a blue dye is added to the wash water, thus helping them reflect all colors of the spectrum more evenly in order to appear white.

Most paints and crayons use a mixture of several colors. When two colors are mixed, the mixture will reflect the colors that both had in common.

Primary, secondary, and complementary

Three colorants that can be mixed in different combinations to produce several other colors are the primary colorants. In mixing red, green, and blue paint the result will be a muddy dark brown. Red and green paint do not combine to form yellow as do red and green light. The mixing of paints and dyes is entirely different from the mixing of colored light.

By 1730, a German engraver named J.C. LeBlon discovered the primary colors red, yellow, and blue are primary in the mixture of pigments. Their combinations produce orange, green, and violet. Many different three-colored combinations can produce the sensation of white light when they are superimposed. When two primary colors such as red and green are combined, they produce a secondary color. A color wheel is used to show the relationship between primary and secondary colors. The colors in this primary and secondary pair are called complementary. Each primary color on the wheel is opposite the secondary color formed by the mixture of the two primary colors. And each secondary color produced by mixing two primary colors lies half-way between them on a color wheel. The complementary colors produce white light when they are combined.

Colors are everywhere

Color influences many of our daily decisions, consciously or unconsciously, from what we eat to what we wear. Color enhances the quality of our lives, it helps us to fully appreciate the beauty of colors. Colors are also an important function of the psychology and physiology of human sensation. Even before the ancient civilizations in prehistoric times, color symbolism was already in use.

Different colors have different meanings that are universal. Colors can express blue moods. On the other hand, these could be moods of tranquility or moods of conflict, sorrow or pleasure, warm and cold, boring or stimulating. In several parts of the world, people have specific meanings for different colors. An example is how Eskimos indicate the different numbers of snow conditions. They have seventeen separate words for white snow. In the west the bride wears white; in China and in the Middle East area white is worn for mourning. Of all colors, the most conspicuous is red.

KEY TERMS

Beams— Many rays of light.

Colorant— A chemical substance that gives color to such materials as ink, paint, crayons, and chalk.

Diffraction— The bending of light.

Hue— The observable visual difference between two wavelengths of color.

Light— A form of energy that travels in waves.

Mirage— An optical illusion.

Pigment— A substance which becomes paint or ink when it is mixed with a liquid.

Ray— A thin line of light.

Reflection— The change in direction of light when it strikes a substance but does not pass through it.

Refraction— The bending of light that occurs when traveling from one medium to another, such as air to glass or air to water.

Spectrum— A display of the intensity of radiation versus wavelength.

The color red can be violent, aggressive, and exciting. The expression “seeing red” indicates one’s anger in most parts of the world. Red appears in more national and international colors and red cars are more often used than any other color. Homes can be decorated to suit the personalities of the people living in them. Warm shades are often used in living rooms because it suggests sociability. Cool shades have a quieting effect, suitable for study areas. Hospitals use appropriate colors depending on those that appeal to patients in recovery, in surgery, or very sick patients. Children in schools are provided bright colored rooms. Safety and certain color codes are essential. The color red is for fire protection, green is for first aid, and red and green colors are for traffic lights.

Human beings owe their survival to plants. The function of color in the flowering plants is to attract bees and other insects in order to promote pollination. The color of fruits attract birds and other animals which eat the fruit and help to distribute the seeds. The utmost relationship between humans and animals and plants are the chlorophylls. The green coloring substance of leaves and the yellowish green chlorophyll is associated with the production of carbohydrates by photosynthesis in plants. Life and the quality of Earth’s atmosphere depends on photosynthesis.

Resources

BOOKS

Mausfield, Rainer, and Dieter Heyer. Colour Perception: Mind and the Physical World. New York: Oxford University Press, USA, 2004.

Parker, Steve. The Science of Light: Projects and Experiments With Light And Color. Oxford, UK: Heinemann, 2005.

Pinna, Baingio, ed. Color, Line, and Space: The Neuroscience of Spatio-Chromatic Vision. Leiden, Netherlands: Brill Academic Pub, 2006.

Valberg, Arne. Light, Vision, Color. Hoboken, NJ: John Wiley & Sons, 2005.

Nasrine Adibe

Color

Color is a complex and fascinating subject. Several fields of science are involved in explaining the phenomenon of color. The physics of light , the chemistry of colorants, the psychology and physiology of human emotion are all related to color. Since the beginning of history, people of all cultures have tried to explain why there is light and why we see colors. Some people have regarded color with the same mixture of fear, reverence, and curiosity with which they viewed other natural phenomena. In recent years scientists, artists, and other scholars have offered interpretations of the sun , light, and color differences.

Color perception plays an important role in our lives and enhances the quality of life. This influences what we eat and wear. Colors help us to understand and appreciate the beauty of sunrise and sunset, the artistry of paintings, and the beauty of a bird's plumage. Because the sun rises above the horizon in the east, it gives light and color to our world. As the sun sets to the west, it gradually allows darkness to set in. Without the sun we would not be able to distinguish colors. The energy of sunlight warms the earth , making life possible; otherwise, there would be no plants to provide food. We are fortunate to have light as an essential part of our planet .

Light and color

Colors are dependent on light, the primary source of which is sunlight. It is difficult to know what light really is, but we can observe its effects. An object appears colored because of the way it interacts with light. A thin line of light is called a ray; a beam is made up of many rays of light. Light is a form of energy that travels in waves. Light travels silently over long distances at a speed of 190,000 mi (300,000 km) a second. It takes about eight minutes for light to travel from the sun to the earth. This great speed explains why light from shorter distances seems to reach us immediately.

When we talk about light, we usually mean white light. When white light passes through a prism (a triangular transparent object) something very exciting happens. The colors that make up white light disperse into seven bands of color. These bands of color are called a spectrum (from the Latin word for image). When a second prism is placed in just the right position in front of the bands of this spectrum, they merge to form invisible white light again. Isaac Newton (1642-1727) was a well known scientist who conducted research on the sun, light, and color. Through his experiments with prisms, he was the first to demonstrate that white light is composed of the colors of the spectrum.

Seven colors constitute white light: red, orange, yellow, green, blue, indigo, and violet. Students in school often memorize acronyms like ROY G BIV, to remember the seven colors of the spectrum and their order. Sometimes blue and indigo are treated as one color. In any spectrum the bands of color are always organized in this order from left to right. There are also wavelengths outside the visible spectrum, such as ultraviolet.

Rainbows

A rainbow is nature's way of producing a spectrum. One can usually see rainbows after summer showers, early in the morning or late in the afternoon, when the sun is low. Rain drops act as tiny prisms and disperse the white sunlight into the form of a large beautiful arch composed of visible colors. To see a rainbow one must be located between the sun and raindrops forming an arc in the sky. When sunlight enters the raindrops at the proper angle, it is refracted by the raindrops, then reflected back at an angle. This creates a rainbow. Artificial rainbows can be produced by spiraling small droplets of water through a garden hose, with one's back to the sun. Or, indoors, diamond-shaped glass objects, mirrors , or other transparent items can be used.

Refraction: the bending of light

Refraction is the bending of a light ray as it passes at an angle from one transparent medium to another. As a beam of light enters glass at an angle, it is refracted or bent. The part of the light beam that strikes the glass is slowed down, causing the entire beam to bend. The more sharply the beam bends, the more it is slowed down.

Each color has a different wavelength, and it bends differently from all other colors. Short wavelengths are slowed more sharply upon entering glass from air than are long wavelengths. Red light has the longest wavelength and is bent the least. Violet light has the shortest wavelength and is bent the most. Thus violet light travels more slowly through glass than does any other color.

Like all other wave phenomena, the speed of light depends on the medium through which it travels. As an analogy, think of a wagon that is rolled off a sidewalk onto a lawn at an oblique angle. When the first wheel hits the lawn, it slows down, pulling the wagon toward the grass. The wagon changes direction when one of its wheels rolls off the pavement onto the grass. Similarly, when light passes from a substance of high density into one of low density, its speed increases, and it bends away from its original path. In another example, one finds that the speed and direction of a car will change when it comes upon an uneven surface like a bridge.

Sometimes while driving on a hot sunny day, we see pools of water on the road ahead of us, which vanish mysteriously as we come closer. As the car moves towards it the pool appears to move further away. This is a mirage, an optical illusion. Light travels faster through hot air than it does through cold air. As light travels from one transparent material to another it bends with a different refraction. The road's hot surface both warms the air directly above it and interacts with the light waves reaching it to form a mirage. In a mirage, reflections of trees and buildings may appear upside down. The bending or refraction of light as it travels through layers of air of different temperatures creates a mirage.

Diffraction and interference

Similar colors can be seen in a thin film of oil, in broken glass and on the vivid wings of butterflies and other insects . Scientists explain this process by the terms, diffraction and interference . Diffraction and refraction both refer to the bending of light. Diffraction is the slight bending of light away from its straight line of travel when it encounters the edge of an object in its path. This bending is so slight that it is scarcely noticeable. The effects of diffraction become noticeable only when light passes through a narrow slit. When light waves pass through a small opening or around a small object, they are bent. They merge from the opening as almost circular, and they bend around the small object and continue as if the object were not there at all. Diffraction is the sorting out of bands of different wavelengths of a beam of light.

When a beam of light passes through a small slit or pin hole, it spreads out to produce an image larger than the size of the hole. The longer waves spread out more than the shorter waves. The rays break up into dark and light bands or into colors of the spectrum. When a ray is diffracted at the edge of an opaque object, or passes through a narrow slit, it can also create interference of one part of a beam with another.

Interference occurs when two light waves from the same source interact with each other. Interference is the reciprocal action of light waves. When two light waves meet, they may reinforce or cancel each other. The phenomenon called diffraction is basically an interference effect. There is no essential difference between the phenomena of interference and diffraction.

Light is a mixture of all colors. One cannot look across a light beam and see light waves, but when light waves are projected on a white screen, one can see light. The idea that different colors interfere at different angles implies that the wavelength of light is associated with its colors. A spectrum can often be seen on the edges of an aquarium, glass, mirrors, chandeliers or other glass ornaments. These colored edges suggest that different colors are deflected at different angles in the interference pattern.

The color effects of interference also occur when two or more beams originating from the same source interact with each other. When the light waves are in phase, color intensities are reinforced; when they are out of phase, color intensities are reduced.

When light waves passing through two slits are in phase there is constructive interference, and bright light will result. If the waves arrive at a point on the screen out of phase, the interference will be destructive, and a dark line will result. This explains why bubbles of a nearly colorless soap solution develop brilliant colors before they break. When seen in white light, a soap bubble presents the entire visible range of light, from red to violet. Since the wavelengths differ, the film of soap cannot cancel or reinforce all the colors at once. The colors are reinforced, and they remain visible as the soap film becomes thinner. A rainbow, a drop of oil on water, and soap bubbles are phenomena of light caused by diffraction, refraction, and interference. Colors found in birds such as the blue jay are formed by small air bubbles in its feathers. Bundles of white rays are scattered by suspended particles into their components colors. Interference colors seen in soap bubbles and oil on water are visible in the peacock feathers. Colors of the mallard duck are interference colors and are iridescent changing in hue when seen from different angles. Beetles, dragonflies , and butterflies are as varied as the rainbow and are produced in a number of ways, which are both physical and chemical. Here, the spectrum of colors are separated by thin films and flash and change when seen from different angles.

Light diffraction has the most lustrous colors of mother of pearl. Light is scattered for the blue of the sky which breaks up blue rays of light more readily than red rays.

Transparent, translucent, and opaque

Materials like air, water, and clear glass are called transparent. When light encounters transparent materials, almost all of it passes directly through them. Glass, for example, is transparent to all visible light. The color of a transparent object depends on the color of light it transmits. If green light passes through a transparent object, the emerging light is green; similarly if red light passes through a transparent object, the emerging light is red.

Materials like frosted glass and some plastics are called translucent. When light strikes translucent materials, only some of the light passes through them. The light does not pass directly through the materials. It changes direction many times and is scattered as it passes through. Therefore, we cannot see clearly through them; objects on the other side of a translucent object appear fuzzy and unclear. Because translucent objects are semi-transparent, some ultraviolet rays can go through them. This is why a person behind a translucent object can get a sunburn on a sunny day.

Most materials are opaque. When light strikes an opaque object none of it passes through. Most of the light is either reflected by the object or absorbed and converted to heat . Materials such as wood , stone, and metals are opaque to visible light.

Mixing colors

We do not actually see colors. What we see as color is the effect of light shining on an object. When white light shines on an object it may be reflected, absorbed, or transmitted. Glass transmits most of the light that comes into contact with it, thus it appears colorless. Snow reflects all of the light and appears white. A black cloth absorbs all light, and so appears black. A red piece of paper reflects red light better than it reflects other colors. Most objects appear colored because their chemical structure absorbs certain wavelengths of light and reflects others.

The sensation of white light is produced through a mixture of all visible colored light. While the entire spectrum is present, the eye deceives us into believing that only white light is present. White light results from the combination of only red, green, and blue. When equal brightnesses of these are combined and projected on a screen, we see white. The screen appears yellow when red and green light alone overlap. The combination of red and blue light produces the bluish red color of magenta. Green and blue produce the greenish blue color called cyan. Almost any color can be made by overlapping light in three colors and adjusting the brightness of each color.

Color vision

Scientists today are not sure how we understand and see color. What we call color depends on the effects of light waves on receptors in the eye's retina. The currently accepted scientific theory is that there are three types of cones in the eye. One of these is sensitive to the short blue light waves; it responds to blue light more than to light of any other color. A second type of cone responds to light from the green part of the spectrum; it is sensitive to medium wavelengths. The third type of light sensitive cone responds to the longer red light waves. If all three types of cone are stimulated equally our brain interprets the light as white. If blue and red wavelengths enter the eye simultaneously we see magenta. Recent scientific research indicates that the brain is capable of comparing the long wavelengths it receives with the shorter wavelengths. The brain interprets electric signals that it receives from the eyes like a computer.

Nearly 1,000 years ago, Alhazen, an Arab scholar recognized that vision is caused by the reflection of light from objects into our eyes. He stated that this reflected light forms optical images in the eyes. Alhazen believed that the colors we see in objects depend on both the light striking these objects and on some property of the objects themselves.

Color blindness

Some people are unable to see some colors. This is due to an inherited condition known as color blindness . John Dalton (1766-1844), a British chemist and physicist, was the first to discover color blindness in 1794. He was color blind and could not distinguish red from green. Many color blind people do not realize that they do not distinguish colors accurately. This is potentially dangerous, particularly if they cannot distinguish between the colors of traffic lights or other safety signals. Those people who perceive red as green and green as red are known as red-green color blind. Others are completely color blind; they only see black, gray, and white. It is estimated that 7% of men and 1% of women on Earth are born color blind.

Color effects in nature

We often wonder why the sky is blue, the water in the sea or swimming pools is blue or green, and why the sun in the twilight sky looks red. When light advances in a straight line from the sun to the earth, the light is refracted, and its colors are dispersed. The light of the dispersed colors depends on their wavelengths. Generally the sky looks blue because the short blue waves are scattered more than the longer waves of red light. The short waves of violet light (the shortest of all the light waves) disperse more than those of blue light. Yet the eye is less sensitive to violet than to blue. The sky looks red near the horizon because of the specific angle at which the long red wavelengths travel through the atmosphere. Impurities in the air may also make a difference in the colors that we see.

Characteristics of color

There are three main characteristics for understanding variations in color. These are hue, saturation, and intensity or brightness. Hue represents the observable visual difference between two wavelengths of color. Saturation refers to the richness or strength of color. When a beam of red light is projected from the spectrum onto a white screen, the color is seen as saturated. All of the light that comes to the eye from the screen is capable of exciting the sensation of red. If a beam of white light is then projected onto the same spot as the red, the red looks diluted. By varying the intensities of the white and red beams, one can achieve any degree of saturation. In handling pigments, adding white or gray to a hue is equivalent to adding white light. The result is a decrease in saturation.

A brightly colored object is one that reflects or transmits a large portion of the light falling on it, so that it appears brilliant or luminous. The brightness of the resulting color will vary according to the reflecting quality of the object. The greatest amount of light is reflected on a white screen, while a black screen would not reflect any light.

Mixing colorants, pigments, dyes, and printing

Color fills our world with beauty. We delight in the golden yellow leaves of Autumn and the beauty of Spring flowers. Color can serve as a means of communication, to indicate different teams in sports, or, as in traffic lights, to instruct drivers when to stop and go. Manufacturers, artists, and painters use different methods to produce colors in various objects and materials. The process of mixing of colorants, paints, pigments and dyes is entirely different from the mixing of colored light.

Colorants are chemical substances that give color to such materials as ink, paint, crayons, and chalk. Most colorants consist of fine powders that are mixed with liquids, wax, or other substances that facilitate their application to objects. Dyes dissolve in water. Pigments do not dissolve in water, but they spread through liquids. They are made up of tiny, solid particles, and they do not absorb or reflect specific parts of the spectrum. Pigments reflect a mixture of colors.

When two different colorants are mixed, a third color is produced. When paint with a blue pigment is mixed with paint that has yellow pigments the resulting paint appears green. When light strikes the surface of this paint, it penetrates the paint layer and hits pigment particles. The blue pigment absorbs most of the light. The same color looks different against different background colors. Each pigment subtracts different wavelengths.

Additive and subtractive

All color is derived from two types of light mixture, an additive and a subtractive process. Both additive and subtractive mixtures are equally important to color design and perception. The additive and subtractive elements are related but different. In a subtractive process, blended colors subtract from white light the colors that they cannot reflect. Subtractive light mixtures occur when there is a mixture of colored light caused by the transmittance of white light. The additive light mixture appears more than the white light.

In a subtractive light mixture, a great many colors can be created by mixing a variety of colors. Colors apply only to additive light mixtures. Mixing colored light produces new colors different from the way colorants are mixed. Mixing colorants results in new colors because each colorant subtracts wavelengths of light. But mixing colored lights produces new colors by adding light of different wavelengths.

Both additive and subtractive mixtures of hues adjacent to each other in the spectrum produce intermediate hues. The additive mixture is slightly saturated or mixed with light, the subtractive mixture is slightly darkened. The complimentary pairs mixed subtractively do not give white pigments with additive mixtures.

Additive light mixtures can be used in a number of slide projectors and color filters in order to place different colored light beams on a white screen. In this case, the colored areas of light are added to one another. Subtractive color mixing takes place when a beam of light passes through a colored filter. The filter can be a piece of colored glass or plastic or a liquid that is colored by a dye. The filter absorbs and changes part of the light. Filters and paints absorb certain colors and reflect others.

Subtractive color mixing is the basis of color printing . The color printer applies the colors one at a time. Usually the printer uses three colors: blue, yellow, and red, in addition to black for shading and emphasis. It is quite difficult for a painter to match colors. To produce the resulting colors, trial and error, as well as experimenting with the colors, is essential. It is difficult to know in advance what the resulting color will be. It is interesting to watch a painter trying to match colors.

People who use conventional methods to print books and magazines make colored illustrations by mixing together printing inks. The color is made of a large number of tiny dots of several different colors. The dots are so tiny that the human eye does not see them individually. It sees only the combined effects of all of them taken together. Thus, if half of the tiny dots are blue and half are yellow, the resulting color will appear green.

Dying fabrics is a prehistoric craft. In the past, most dyes were provided solely from plant and animal sources. In antiquity, the color purple or indigo, derived from plants, was a symbol of aristocracy. In ancient Rome, only the emperor was privileged to wear a purple robe.

Today, many dyes and pigments are made of synthetic material. Thousands of dyes and pigments have since been created from natural coal tar, from natural compounds, and from artificially produced organic chemicals. Modern chemistry is now able to combine various arrangements and thus produce a large variety of color.

The color of a dye is caused by the absorption of light of specific wavelengths. Dyes are made of either natural or synthetic material. Chemical dyes tend to be brighter than natural dyes. In 1991 a metamorphic color system was created in a new line of clothes. The color of these clothes changes with the wearer's body temperature and environment. This color system could be used in a number of fabrics and designs.

Sometimes white clothes turn yellow from repeated washing. The clothes look yellow because they reflect more blue light than they did before. To improve the color of the faded clothes a blue dye is added to the wash water, thus helping them reflect all colors of the spectrum more evenly in order to appear white.

Most paints and crayons use a mixture of several colors. When two colors are mixed, the mixture will reflect the colors that both had in common. For example, yellow came from the sap of a tree , from the bark of the birch tree, and onion skins. There were a variety of colors obtained from leaves, fruits , and flowers.

Primary, secondary, and complimentary

Three colorants that can be mixed in different combinations to produce several other colors are the primary colorants. In mixing red, green, and blue paint the result will be a muddy dark brown. Red and green paint do not combine to form yellow as do red and green light. The mixing of paints and dyes is entirely different from the mixing of colored light.

By 1730, a German engraver named J. C. LeBlon discovered the primary colors red, yellow, and blue are primary in the mixture of pigments. Their combinations produce orange, green, and violet. Many different three colored combinations can produce the sensation of white light when they are superimposed. When two primary colors such as red and green are combined, they produce a secondary color. A color wheel is used to show the relationship between primary and secondary colors. The colors in this primary and secondary pair are called complimentary. Each primary color on the wheel is opposite the secondary color formed by the mixture of the two primary colors. And each secondary color produced by mixing two primary colors lies half-way between them on a color wheel. The complimentary colors produce white light when they are combined.

Colors are everywhere

Color influences many of our daily decisions, consciously or unconsciously from what we eat and what we wear. Color enhances the quality of our lives, it helps us to fully appreciate the beauty of colors. Colors are also an important function of the psychology and physiology of human sensation. Even before the ancient civilizations in prehistoric times, color symbolism was already in use.

Different colors have different meanings which are universal. Colors can express blue moods. On the other hand, these could be moods of tranquility or moods of conflict, sorrow or pleasure, warm and cold, boring or stimulating. In several parts of the world, people have specific meanings for different colors. An example is how Eskimos indicate the different numbers of snow conditions. They have seventeen separate words for white snow. In the west the bride wears white, in China and in the Middle East area white is worn for mourning. Of all colors, that most conspicuous and universal is red.

The color red can be violent, aggressive, and exciting. The expression "seeing red" indicates one's anger in most parts of the world. Red appears in more national and international colors and red cars are more often used than any other color. Homes can be decorated to suit the personalities of the people living in them. Warm shades are often used in living rooms because it suggests sociability. Cool shades have a quieting effect, suitable for study areas. Hospitals use appropriate colors depending on those that appeal to patients in recovery, in surgery , or very sick patients. Children in schools are provided bright colored rooms. Safety and certain color codes are essential. The color red is for fire protection, green is for first aid, and red and green colors are for traffic lights.

Human beings owe their survival to plants. The function of color in the flowering plants is to attract bees and other insects—to promote pollination . The color of fruits attract birds and other animals which help the distribution of seeds . The utmost relationship between humans and animals and plants are the chlorophylls. The green coloring substance of leaves and the yellowish green chlorophyll is associated with the production of carbohydrates by photosynthesis in plants. Life and the quality of the earth's atmosphere depends on photosynthesis.

Resources

books

Birren, Faber. Color—A Survey in Words and Pictures. New Hyde Park, NY: University Books, Inc, 1963.

Birren, Faber. History of Color in Painting. New York: Reinhold Publishing Corporation, 1965.

Birren, Faber. Principles of Color. New York: Van Nostrand Reinhold Co., 1969.

Hewitt, Paul. Conceptual Physics. Englewood Cliffs, NJ: Prentice Hall, 2001.

Meadows, Jack. The Great Scientists. New York: Oxford University Press, 1992.

Verity, Enid. Color Observed. New York: Van Nostrand Reinhold Co., 1990.

periodicals

Cunningham, James, and Norman Herr. "Waves." "Light." Hands on Physics Activities with Real Life Applications West Nyack, NY: Center for Applied Research Education, 1994.

Kosvanec, Jim. "Mixing Grayed Color." American Artist 1994.

Suding, Heather, and Jeanne Bucegross. "A Simple Lab Activity to Teach Subtractive Color and Beer's Law," Journal of Chemical Education, 1994.

Nasrine Adibe

KEY TERMS

Beams

—Many rays of light.

Colorant

—A chemical substance that gives color to such materials as ink, paint, crayons and chalk.

Diffraction

—The bending of light.

Hue

—The observable visual different between two wavelengths of color.

Light

—A form of energy that travels in waves.

Mirage

—An optical illusion.

Pigment

—A substance which becomes paint or ink when it is mixed with a liquid.

Ray

—A thin line of light.

Reflection

—The change in direction of light when it strikes a substance but does not pass through it.

Refraction

—The bending of light that occurs when traveling from one medium to another, such as air to glass or air to water.

Spectrum

—A display of the intensity of radiation versus wavelength.

Color

Color is a property of light that depends on the frequency of light waves. Frequency is defined as the number of wave segments that pass a given point every second. In most cases, when people talk about light, they are referring to white light. The best example of white light is ordinary sunlight: light that comes from the Sun.

Light is a form of electromagnetic radiation: a form of energy carried by waves. The term "electromagnetic radiation" refers to a vast range of energy waves, including gamma rays, X rays, ultraviolet rays, visible light, infrared radiation, microwaves, radar, and radio waves. Of all these forms, only one can be detected by the human eye: visible light.

White light and color

White light (such as sunlight) and colors are closely related. A piece of glass or crystal can cause a beam of sunlight to break up into a rainbow: a beautiful separation of colors. The technical term for a rainbow is a spectrum. The colors in a spectrum range from deep purple to brilliant red. One way to remember the colors of the spectrum is with the mnemonic device (memory clue) ROY G. BIV, which stands for Red, Orange, Yellow, Green, Blue, Indigo, and Violet.

English physicist Isaac Newton (1642–1727) was the first person to study the connection between white light and colors. Newton caused a beam of white light to fall on a glass prism and found that the white light was broken up into a spectrum. He then placed a second prism in front of the first and found that the colors could be brought back together into a beam of white light. A rainbow is a naturally occurring illustration of Newton's experiment. Instead of a glass prism, though, it is tiny droplets of rainwater that cause sunlight to break up into a spectrum of colors, a spectrum we call a rainbow.

Color and wavelength

The word "color" actually refers to the light of a particular color, such as red light, yellow light, or blue light. The color of a light beam depends on just one factor: the wavelength of the light. Wavelength is defined as the distance between two exactly identical parts of a given wave. Red light consists of light waves with a wavelength of about 700 nanometers (billionths of a meter), yellow light has wavelengths of about 550 nanometers, and blue light has wavelengths of about 450 nanometers. But the wavelengths of colored light are not limited to specific ranges. For example, waves that have wavelengths of 600, 625, 650, and 675 nanometers would have orange, orangish-red, reddish-orange, and, finally, red colors.

Words to Know

Color: A property of light determined by its wavelength.

Colorant: A chemical substance—such as ink, paint, crayons, or chalk—that gives color to materials.

Complementary colors: Two colors that, when mixed with each other, produce white light.

Electromagnetic radiation: A form of energy carried by waves.

Frequency: The number of segments in a wave that pass a given point every second.

Gray: A color produced by mixing white and black.

Hue: The name given to a color on the basis of its frequency.

Light: A form of energy that travels in waves.

Nanometer: A unit of length; this measurement is equal to one-billionth of a meter.

Pigment: A substance that displays a color because of the wavelengths of light that it reflects.

Primary colors: Colors that, when mixed with each other, produce white light.

Shade: The color produced by mixing a color with black.

Spectrum: The band of colors that forms when white light is passed through a prism.

Tint: The color formed by mixing a given color with white.

Tone: The color formed by mixing a given color with gray (black and white).

Wavelength: The distance between two exactly identical parts of a wave.

The color of objects

Light can be seen only when it reflects off some object. For example, as you look out across a field, you cannot see beams of light passing through the air, but you can see the green of trees, the brown of fences, and the yellow petals of flowers because of light reflected by these objects.

To understand how objects produce color, imagine an object that reflects all wavelengths of light equally. When white light shines on that object, all parts of the spectrum are reflected equally. The color of the object is white. (White is generally not regarded as a color but as a combination of all colors mixed together.)

Now imagine that an object absorbs (soaks up) all wavelengths of light that strike it. That is, no parts of the spectrum are reflected. This object is black, a word that is used to describe an object that reflects no radiation.

Finally, imagine an object that reflects light with a wavelength of about 500 nanometers. Such an object will absorb all wavelengths of light except those close to 500 nanometers. It will be impossible to see red light (700 nanometers), violet light (400 nanometers), or blue light (450 nanometers) because those parts of the spectrum are all absorbed by the object. The only light that is reflected—and the only color that can be seen—is green, which has a wavelength of about 500 nanometers.

Primary and complementary colors

White light can be produced by combining all colors of the spectrum at once, as Newton discovered. However, it is also possible to make white light by combining only three colors in the spectrum: red, green, and blue. For this reason, these three colors of light are known as the primary colors. (For more on the concept of primary colors, see subhead titled "Pigments.") In addition to white light, all colors of the spectrum can be produced by an appropriate mixing of the primary colors. For example, red and green lights will combine to form yellow light.

It is also possible to make white light by combining only two colors, although these two colors are not primary colors. For example, the combination of a bluish-violet light and a yellow light form white light. Any two colors that produce white light, such as bluish-violet and yellow, are known as complementary colors.

The language of colors

A special vocabulary is used to describe colors. The fundamental terms include:

Hue: The basic name of a color, as determined by its frequency. Light with a wavelength of 600 nanometers is said to have an orange hue.

Gray: The color produced by mixing white and black.

Shade: The color produced by mixing a color with black. For example, the shade known as maroon is formed by mixing red and black.

Tint: The color formed by mixing a color with white. Pink is produced when red and white are mixed.

Tone: The color formed by mixing a color with gray (black and white). Red plus white plus black results in the tone known as rose.

Pigments

A pigment is a substance that reflects only certain wavelengths of light. Strictly speaking, there is no such thing as a white pigment because such a substance would reflect all wavelengths of light. A red pigment is one that reflects light with a wavelength of about 700 nanometers; a blue pigment is one that reflects light with a wavelength of about 450 nanometers.

The rules for combining pigment colors are different from those for combining light colors. For example, combining yellow paint and blue paint produces green paint. Combining red paint with yellow paint produces orange paint. And combining all three of the primary colors of paints—yellow, blue, and red—produces black paint.

Other color phenomena

Color effects occur in many different situations in the natural world. For example, the swirling colors in a soap bubble are produced by interference, a process in which light is reflected from two different surfaces very close to each other. The soap bubble is made of a very thin layer of soap: the inside and outside surfaces are less than a millimeter away from each other. When light strikes the bubble, then, it is reflected from both the outer surface and from the inside surface of the bubble. The two reflected beams of light interfere with each other in such a way that some wavelengths of light are reinforced, while others are canceled out. It is by this mechanism that the colors of the soap bubble are produced.

[See also Light; Spectroscopy ]

92. Color

achromaticity

1. the total absence of color.

2. the ability to emit, reflect, or transmit light without breaking down into separate colors. Also achromatism.

achromatopsy, achromatopsia

color blindness. Also called acritochromacy .

acyanoblepsia

a variety of color blindness characterized by an inability to distinguish blue.

albescence

the condition of being or becoming white or whitish. —albescent , adj.

albication

the process of turning white or whitish.

chatoyancy

the condition or quality of changing in color or luster depending on the angle of light, exhibited especially by a gemstone that reflects a single shaft of light when cut in cabochon form. —chatoyant , adj.

chromatics

the branch of opties that studies the properties of colors.

chromatism

1. Opties, dispersion or distortion of color.

2. abnormal coloration. See also 54. BOTANY .

chromatology

the study of colors. Also called chromatography .

chromatrope

an instrument consisting of an arrangement of colored dises which, when rotated rapidly, give the impression of colors flowing to or from the center.

chromophobia

an abnormal fear of colors.

chromoptometer

a device for measuring the degree of a person’s sense of color.

chromotypography, chromotypy

the process of color printing.

colorimetry

the measurement of the physical intensity of colors, as opposed to their subjective brightness. —colorimeter , n. —colorimetric, colorimetrical , adj.

cyanometry

the measurement of the intensity of the sky’s blue color. —cyanometer , n. —cyanometric , adj.

Daltonism

red-green color blindness.

deuteranopia

a defect of the eyesight in which the retina does not respond to green. —deuteranope , n. —deuteranopic , adj.

dichroism

a property, peculiar to certain crystals, of reflecting light in two different colors when viewed from two different directions. —dichroic , adj.

dichromatism

1. the quality of being dichromatic, or having two colors.

2. a form of color blindness in which the sufferer can perceive only two of the three primary colors and their variants. —dichromatic , adj.

dyschromatopsia

difficulty in telling colors apart; color blindness.

erythrophobia

an abnormal fear of the color red.

floridity

the condition of being florid or highly colored, especially reddish, used especially of the complexion. —florid , adj.

glaucescence

1. the state or quality of being a silvery or bluish green in color.

2. the process of turning this color. —glaucescent , adj.

hyperchromatism

the occurrence of unusually intense coloration. —hyperchromatic , adj.

indigometer

an instrument used for determining the strength of an indigo solution.

indigometry

the practice and art of determining the strength and coloring power of an indigo solution.

iridescence

the state or condition of being colored like a rainbow or like the light shining through a prism. —iridescent , adj.

irisation

the process of making or becoming iridescent.

iriscope

a polished black glass, the surface of which becomes iridescent when it is breathed upon through a tube.

melanoscope

an optical device composed of red and violet glass that transmits red light only, used for distinguishing red in varicolored flames.

metachromatism

change in color, especially as a result of change in temperature.

monochromatism

1. the quality of being of only one color or in only one color, as a work of art.

2. a defect of eyesight in which the retina cannot perceive color. —monochromatic , adj.

mordancy, mordacity

the property of acting as a flxative in dyeing. — mordant, n., adj.

opalescence

the quality of being opallike, or milkily iridescent. —opalescent , adj.

pallidity

a faintness or deficiency in color. —pallid , adj.

panchromatism

the quality or condition of being lsensitive to all colors, as certain types of photographic film. —panchromatic , adj.

polychromatism

the state or quality of being multicolored. —polychromatic, polychromie , adj.

protanopia

a defect of the eyesight in which the retina does not respond to red. —protanope , n. —protanopic , adj.

rubescence

1. the state, condition, quality, or process of becoming or being red.

2. a blush.

3. the act of blushing. —rubescent , adj.

rufescence

1. the tendency to turn red or reddish.

2. reddishness. —rufescent , adj.

spectrogram

a photograph of a spectrum. Also called spectrograph .

spectrograph

1. an optical device for breaking light down into a spectrum and recording the results photographically.

2. a spectrogram. —spectrographic , adj.

spectrography

the technique of using a spectrograph and producing spectrograms.

trichroism

a property, peculiar to certain crystals, of transmitting light of three different colors when viewed from three different directions. Also trichromatism . —trichroic , adj.

trichromatism

1. the condition of having, using, or combining three colors.

2. trichroism. —trichromatic , adj.

tritanopia

a defect of the eyesight in which the retina does not respond to blue and yellow. —tritanope , n. —tritanopic , adj.

verdancy

the quality or condition of being green, as the condition of being covered with green plants or grass or inexperience attributable to youth. —verdant , adj.

viridescence

1. the state or quality of being green or greenish.

2. greenishness. —viridescent , adj.

xanthocyanopsy, xanthocyanopy

a form of color blindness in which only yellow and blue can be perceived.