From Wikipedia, the free encyclopedia
| — Spectral coordinates —
| — Common connotations —
|sunshine, warmth, fun, happiness, warning, friendship, caution, slow, intelligence, cowardice, love, animal crossing, Mardi Gras, summer, Easter, autumn, electricity, liberalism/libertarianism, hope, optimism, imagination, curiosity
— Color coordinates —
||(r, g, b)
||(255, 255, 0)
|B: Normalized to [0–255] (byte)
Yellow is the color evoked by light that stimulates both the L and M (long and medium wavelength) cone cells of the retina about equally, with no significant stimulation of the S (short-wavelength) cone cells. Light with a wavelength of 570–580 nm is yellow, as is light with a suitable mixture of somewhat longer and shorter wavelengths. Yellow's traditional RYB complementary color is purple, violet, or indigo, while its colorimetrically defined complementary color in both RGB and CMYK color spaces is blue. Yellow is one of the three primary colors. The other two are red and blue.
Etymology and definitions
The word yellow comes from the Old English geolu, or geolwe which derived from the Proto-Germanic word gelwaz. The oldest known use of this word in English is in the Old English poem Beowulf, in a description of a shield made of wood from a yew tree.
In the English language, yellow has traditionally been associated with jaundice and cowardice. Yellow is associated with the word "caution" and is the second light on stop lights; in American slang, a coward can be said to be "yellowbellied" or "yellow". The color is associated with aging as well, for both people and objects (e.g. "yellowed" paper). Ethnographically, the term "yellow" has been used as a slang term for both Asians ("yellow peril") and, in the early 20th century, light-skinned African-Americans (High yellow).
"Yellow" ("giallo"), in Italy, refers to crime stories, both fictional and real. This association began in about 1930, when the first series of crime novels published in Italy had yellow covers. The term "yellow movie" (黃色電影) can refer to films of pornographic nature in Chinese culture, and is analogous to the English "blue movie". Lastly, it is associated with sensational journalistic practices, or yellow journalism, and resistance to militant trade unions.
Complements of yellow have a dominant wavelength in the range 380 to 480 nm. The green lines show several possible pairs of complementary colors with respect to different blackbody color temperature neutrals, illustrated by the "Planckian locus
Hunt defines that "two colors are complementary when it is possible to reproduce the tristimulus values of a specified achromatic stimulus by an additive mixture of these two stimuli." That is, when two colored lights can be mixed to match a specified white (achromatic, non-colored) light, the colors of those two lights are complementary. This definition, however, does not constrain what version of white will be specified. In the nineteenth century, the scientists Grassmann and Helmholtz did experiments in which they concluded that finding a good complement for spectral yellow was difficult, but that the result was indigo, that is, a wavelength that today's color scientists would call violet. Helmholtz says "Yellow and indigo blue" are complements. Grassman reconstructs Newton's category boundaries in terms of wavelengths and says "This indigo therefore falls within the limits of color between which, according to Helmholtz, the complementary colors of yellow lie." Newton's own color circle has yellow directly opposite the boundary between indigo and violet. These results, that the complement of yellow is a wavelength shorter than 450 nm, are derivable from the modern CIE 1931 system of colorimetry if it is assumed that the yellow is about 580 nm or shorter wavelength, and the specified white is the color of a blackbody radiator of temperature 2800 K or lower (that is, the white of an ordinary incandescent light bulb). More typically, with a daylight-colored or around 5000 to 6000 K white, the complement of yellow will be in the blue wavelength range, which is the standard modern answer for the complement of yellow.
Stars of spectral classes F and G, such as our sun Sol, have color temperatures that make them look "yellowish". The first astronomer to classify stars according to their color was F. G. W. Struve in 1827. One of his classifications was flavae, or yellow, and this roughly corresponded to stars in the modern spectral range F5 to K0. The Strömgren photometric system for stellar classification includes a 'y' or yellow filter that is centered at a wavelength of 550 nm and has a bandwidth of 20–30 nm.
- Yellow-breasted Chats (Icteria virens) are large foraging songbird found in southern parts of Canada, the United States, Mexico, and Central America. They are olive with a white bellie and a yellow throat and breast, with a long tail, a thick heavy bill, a large white eye ring, and dark legs.
- The Yellowhammer (Emberiza citrinella) is a passerine in the bunting family Emberizidae. It breeds across Europe and much of Asia. Most yellowhammers are resident, but some far northern birds migrate south in winter. It is common in all sorts of open areas with some scrub or trees. They are large with a thick seed-eater's bill. The males have a bright yellow head, yellow underparts, and a heavily streaked brown back. Females are much duller and more streaked below.
- The Yellow-shafted Flicker (Colaptes auratus) is a large woodpecker species of eastern North America. They have yellow shafts on their wing and tail feathers.
- Yellowtail is the common name for dozens of different fish species that have yellow tails or a yellow body.
- Yellowfin tuna (Thunnus albacares) is a species of tuna, having bright yellow anal and second dorsal fins. Found in tropical and subtropical seas and weighing up to 200 kg (440 lb), it is caught as a replacement for the depleted stocks of bluefin tuna.
- Yellowjackets are black-and-yellow wasps of the genus Vespula or Dolichovespula (though some can be black-and-white, the most notable of these being the bald-faced hornet, Dolichovespula maculata). They can be identified by their distinctive black-and-yellow color, small size (slightly larger than a bee), and entirely black antennae.
Electric yellow vs. process yellow
The color box at right shows the most intense yellow representable in 8-bit RGB color model; yellow is a secondary color in an additive RGB space.
The measured light spectrum from yellow pixels on a typical computer display is complex, and very unlike the reflectance spectrum of a yellow object such as a banana.
|Process yellow (subtractive primary, sRGB approximation)
— Color coordinates —
||(r, g, b)
||(255, 239, 0)
||(h, s, v)
||(56°, 100%, 100%)
|B: Normalized to [0–255] (byte)
Process yellow (also known as pigment yellow, printer's yellow or canary yellow) is one of the three colors typically used as subtractive primary colors, along with magenta and cyan. The CMYK system for color printing is based on using four inks, one of which is a yellow color. This is in itself a standard color, and a fairly narrow range of yellow inks or pigments are used. Process yellow is based on a colorant that reflects the preponderance of red and green light, and absorbs most blue light, as in the reflectance spectra shown in the figure on the lower right.
Because of the characteristics of paint pigments and use of different color wheels, painters traditionally regard the complement of yellow as the color indigo or blue-violet.
Process yellow is not an RGB color, and there is no fixed conversion from CMYK primaries to RGB. Different formulations are used for printer's ink, so there can be variations in the printed color that is pure yellow ink.
The first recorded use of canary yellow as a color name in English was in 1789.
Lasers emitting in the yellow part of the spectrum are much less common than most other colors. They are also much more expensive than comparable lasers because the difference in energy levels between the metastable and the ground state required for laser action is difficult to create for yellow photons. In commercial products diode pumped solid state (DPSS) technology is employed to create the yellow light. An infrared laser diode at 808 nm is used to pump a crystal of neodymium-doped yttrium vanadium oxide (Nd:YVO4) or neodymium-doped yttrium aluminium garnet (Nd:YAG) and induces it to emit at two frequencies (wavelengths of 1064 nm and 1342 nm) simultaneously. This deeper infrared light is then passed through another crystal containing potassium, titanium and phosphorus (KTP), whose non-linear properties generate light at a frequency that is the sum of the two incident beams; in this case corresponding to the wavelength of 593.5 nm ("yellow"). This not a true yellow, as it exceeds 580 nm. A truly yellow laser has yet to be made.
Minerals and chemistry
Structure of Titan Yellow
Reflectance spectra of yellow pigments, as a percentage of white (Abney 1891)
- Yellow ochre (also known as Mars yellow, Pigment yellow 42, 43), hydrated ferric oxide (Fe2O3.H2O), is a naturally occurring pigment found in clays in many parts of the world. It is non-toxic and has been used in painting since prehistoric times.
- Indian yellow is a transparent, fluorescent pigment used in oil paintings and watercolors. Originally magnesium euxanthate, it was claimed to have been produced from the urine of Indian cows fed only on mango leaves. It has now been replaced by synthetic Indian yellow hue.
- Naples Yellow (lead antimonate yellow) is one of the oldest synthetic pigments, derived from the mineral bindheimite and used extensively up to the 20th century. It is toxic and nowadays is replaced in paint by a mixture of modern pigments.
- Cadmium Yellow (cadmium sulfide, CdS) has been used in artists' paints since the mid-19th century. Because of its toxicity, it may nowadays be replaced by azo pigments.
- Chrome Yellow (lead chromate, PbCrO4), derived from the mineral crocoite, was used by artists in the earlier part of the 19th century, but has been largely replaced by other yellow pigments because of the toxicity of lead.
- Titanium Yellow (nickel antimony titanium yellow rutile, NiO.Sb2O5.20TiO2) is created by adding small amounts of the oxides of nickel and antimony to titanium dioxide and heating. It is used to produce yellow paints with good white coverage and has the LBNL paint code "Y10".
- Gamboge is an orange-brown resin, derived from trees of the genus Garcinia, which becomes yellow when powdered. It was used as a watercolor pigment in the far east from the 8th century - the name "gamboge" is derived from "Cambodia" - and has been used in Europe since the 17th century.
- Orpiment, also called King's Yellow or Chinese Yellow is arsenic trisulfide (As2S3) and was used as a paint pigment until the 19th century when, because of its high toxicity and reaction with lead-based pigments, it was generally replaced by Cadmium Yellow.
In human culture
- The ancient Maya associated the color yellow with the direction South. The Maya glyph for "yellow" (k'an) also means "precious" or "ripe".
- The word yellow can be used as an adjective meaning cowardly.
- Cyclist Lance Armstrong's "Livestrong" campaign has also been associated with the color yellow.
Yellow Submarine model at Liverpool Airport in November 2007
- Yellow was also the color of the New Party in the Republic of China (Taiwan), which supports Chinese reunification.
- In the United States, a yellow dog Democrat was a Southern voter who consistently voted for Democratic candidates in the late 19th and early 20th centuries because of lingering resentment against the Republicans dating back to the Civil War and Reconstruction period. Today the term refers to a hard-core Democrat, supposedly referring to a person who would vote for a "yellow dog" before voting for a Republican.
- Yellow is also associated in the United States with the Libertarian Party, to contrast with the Democratic Party (blue) and Republican Party (red).
- In the United Kingdom, The Monster Raving Loony Party (OMRLP) has made use of yellow, along with black, as its primary party colors.
- During the People Power Revolution of 1986, yellow was the dominant theme, the color being associated with former Philippine President Corazon Aquino. It is now a symbol of both support for her as well as in commemoration of the popular revolt.
- In Europe, many liberal parties use yellow in a combination with blue, such as FDP (Germany), LIF (Austria), Reform Party of Estonia and Liberal and Centre Union (Lithuania).
T.Mk1 during a display at Kemble
Air Day, England, in 2008. This aircraft is painted in the yellow color of a former RAF display team - the Yellowjacks
- In some countries, taxicabs are commonly yellow. This practice began in Chicago, where taxi entrepreneur John D. Hertz painted his taxis yellow based on a University of Chicago study alleging that yellow is the color most easily seen at a distance.
- In Canada and the United States, school buses are almost uniformly painted a yellow color (often referred to as "school bus yellow") for purposes of visibility and safety, and British bus operators such as FirstGroup plc are attempting to introduce the concept there.
- "Caterpillar yellow" and "high-visibility yellow" are used for highway construction equipment.
- In the rules of the road, yellow (called "amber" in Britain) is a traffic light signal warning that the period in which passage is permitted is coming to an end. It is intermediate between green (go) and red (stop). In railway signaling, yellow is often the color for warning, slow down, such as with distant signals.
- Yellow warning signs, especially with black wording, borders, or alternating stripes, are used in many countries around the world to indicate caution, both as road signs and for other uses such as "caution, slippery floor".
- Several light rail and rapid transit lines on various public transportation have a Yellow Line.
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