Red

Red
Spectral coordinates
Wavelength	approx. 625–740 nm
Frequency	~480–400 THz
Color coordinates
Hex triplet	#FF0000
sRGBB (r, g, b)	(255, 0, 0)
Source	X11
	B: Normalized to (byte);

Red is the color at the end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres. It is a primary color in the RGB color model and the CMYK color model, and is the complementary color of cyan. Reds range from the brilliant yellow-tinged scarlet and vermillion to bluish-red crimson, and vary in shade from the pale red pink to the dark red burgundy. The red sky at sunset results from Rayleigh scattering, while the red color of the Grand Canyon and other geological features is caused by hematite or red ochre, both forms of iron oxide. Iron oxide also gives the red color to the planet Mars. The red colour of blood comes from protein hemoglobin, while ripe strawberries, red apples and reddish autumn leaves are colored by anthocyanins.

Red pigment made from ochre was one of the first colors used in prehistoric art. The Ancient Egytians and Mayans colored their faces red in ceremonies; Roman generals had their bodies colored red to celebrate victories. It was also an important color in China, where it was used to colour early pottery and later the gates and walls of palaces. In the Renaissance, the brilliant red costumes for the nobility and wealthy were dyed with kermes and cochineal. The 19th century brought the introduction of the first synthetic red dyes, which replaced the traditional dyes. Red also became the color of revolution; Soviet Russia adopted a red flag following the Bolshevik Revolution in 1917, later followed by China, Vietnam, and other communist countries.

Since red is the color of blood, it has historically been associated with sacrifice, danger and courage. Modern surveys in Europe and the United States show red is also the color most commonly associated with heat, activity, passion, sexuality, anger, love and joy. In China, India and many other Asian countries it is the color of symbolizing happiness and good fortune.

Shades and variations

Pure, or solid red, the color of most ripe raspberries.
Scarlet is one quarter of the way between the colors red and orange. It is the colour worn by a cardinal of the Roman Catholic Church.
The cardinal takes its name from the colour worn by Roman Catholic cardinals.
Pink is a pale shade of red. Cherry blossoms in the Tsutsujigaoka Park, Sendai, Miyagi, Japan.
Vermilion is similar to scarlet, but slightly more orange. This is sindoor, a red cosmetic powder used in India; Some Hindu women put a stripe of sindoor in their hair to show they are married.
Maple tree with red leaves in the morning mist Estonia
Crimson is a strong, deep red containing a little blue. The emblem of Harvard University.
Maroon is a dark brownish red. Its name comes from marron, the French word for chestnut.
Ruby is the colour of a cut and polished ruby gemstone.
Burgundy, claret, or Wine red, is a very dark red containing a little blue. In France this colour is known as Bordeaux.

(Lists of shades of red and shades of pink are found at the end of this article.)

In science and nature

Seeing red

Bulls, like dogs and many other animals, have dichromacy, which means they cannot distinguish the color red. They charge the matador's cape because of its motion, not its color.

The human eye sees red when it looks at light with a wavelength between approximately 625 and 740 nanometers. It is a primary color in the RGB color model and the light just past this range is called infrared, or below red, and cannot be seen by human eyes, although it can be sensed as heat. In the language of optics, red is the color evoked by light that stimulates neither the S or the M (short and medium wavelength) cone cells of the retina, combined with a fading stimulation of the L (long-wavelength) cone cells.

Primates can distinguish the full range of the colors of the spectrum visible to humans, but many kinds of mammals, such as dogs and cattle, have dichromacy, which means they can see blues and yellows, but cannot distinguish red and green (both are seen as gray). Bulls, for instance, cannot see the red color of the cape of a bullfighter, but they are agitated by its movement. (See color vision).

One theory for why primates developed sensitivity to red is that it allowed ripe fruit to be distinguished from unripe fruit and inedible vegetation. This may have driven further adaptations by species taking advantage of this new ability, such as the emergence of red faces.

Red light is used to help adapt night vision in low-light or night time, as the rod cells in the human eye are not sensitive to red.

Red illumination was (and sometimes still is) used as a safelight while working in a darkroom as it does not expose most photographic paper and some films. Today modern darkrooms usually use an amber safelight.

In color theory and on a computer screen

On the color wheel long used by painters, and in traditional color theory, red is one of the three primary colors, along with blue and yellow. Painters in the Renaissance mixed red and blue to make violet: Cennino Cennini, in his 15th-century manual on painting, wrote, "If you want to make a lovely violet colour, take fine lac , ultramarine blue (the same amount of the one as of the other) with a binder" he noted that it could also be made by mixing blue indigo and red hematite.

In modern color theory, also know

Release Date :

12:00am on Monday 3rd September 2007