RGB color model - AbsoluteAstronomy.com

The RGB color model is an additive

Additive color

An additive color model involves light emitted directly from a source or illuminant of some sort. The additive reproduction process usually uses red, green and blue light to produce the other colors. Combining one of these additive primary colors with another in equal amounts produces the...

color model in which red

Red

Red is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths of light discernible by the human eye, in the wavelength range of roughly 630–740 nm. Longer wavelengths than this are called infrared , and cannot be seen by the naked eye...

, green

Green

Green is a color, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 520–570 nanometres. In the subtractive color system, it is not a primary color, but is created out of a mixture of yellow and blue, or yellow and cyan; it is considered...

, and blue

Blue

Blue is a colour, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 440–490 nm. It is considered one of the additive primary colours. On the HSV Colour Wheel, the complement of blue is yellow; that is, a colour corresponding to an equal...

light is added together in various ways to reproduce a broad array of color

Color

Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...

s. The name of the model comes from the initials of the three additive primary colors, red, green, and blue.

The main purpose of the RGB color model is for the sensing, representation, and display of images in electronic systems, such as televisions and computers, though it has also been used in conventional photography

Photography

Photography is the art, science and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor or chemically by means of a light-sensitive material such as photographic film...

. Before the electronic age, the RGB color model already had a solid theory behind it, based in human perception of colors.

RGB is a device-dependent color model: different devices detect or reproduce a given RGB value differently, since the color elements (such as phosphors or dyes) and their response to the individual R, G, and B levels vary from manufacturer to manufacturer, or even in the same device over time. Thus an RGB value does not define the same color across devices without some kind of color management

Color management

In digital imaging systems, color management is the controlled conversion between the color representations of various devices, such as image scanners, digital cameras, monitors, TV screens, film printers, computer printers, offset presses, and corresponding media.The primary goal of color...

.

Typical RGB input devices are color TV and video camera

Professional video camera

A professional video camera is a high-end device for creating electronic moving images...

s, image scanner

Image scanner

In computing, an image scanner—often abbreviated to just scanner—is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. Common examples found in offices are variations of the desktop scanner where the document is placed on a glass...

s, and digital camera

Digital camera

A digital camera is a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor. It is the main device used in the field of digital photography...

s. Typical RGB output devices are TV sets of various technologies (CRT

Cathode ray tube

The cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms , pictures , radar targets and...

, LCD

Liquid crystal display television

Liquid-crystal display televisions are television sets that use LCD display technology to produce images. LCD televisions are thinner and lighter than cathode ray tube of similar display size, and are available in much larger sizes...

, plasma

Plasma display

A plasma display panel is a type of flat panel display common to large TV displays or larger. They are called "plasma" displays because the technology utilizes small cells containing electrically charged ionized gases, or what are in essence chambers more commonly known as fluorescent...

, etc.), computer

Computer display

A monitor or display is an electronic visual display for computers. The monitor comprises the display device, circuitry, and an enclosure...

and mobile phone

Mobile phone

A mobile phone is a device which can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile network operator...

displays, video projector

Video projector

A video projector is an image projector that receives a video signal and projects the corresponding image on a projection screen using a lens system. All video projectors use a very bright light to project the image, and most modern ones can correct any curves, blurriness, and other...

s, multicolor LED

LEd

LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....

displays, and large screens such as JumboTron

Jumbotron

A JumboTron is a large-screen television using technology developed by Sony, typically used in sports stadiums and concert venues to show close-up shots of the event. Although JumboTron is a registered trademark owned by the Sony Corporation, the word jumbotron is often used by the public as a...

, etc. Color printers, on the other hand, are not RGB devices, but subtractive color

Subtractive color

A subtractive color model explains the mixing of paints, dyes, inks, and natural colorants to create a full range of colors, each caused by subtracting some wavelengths of light and reflecting the others...

devices (typically CMYK color model

CMYK color model

The CMYK color model is a subtractive color model, used in color printing, and is also used to describe the printing process itself. CMYK refers to the four inks used in some color printing: cyan, magenta, yellow, and key...

).

This article discusses concepts common to all the different color spaces that use the RGB color model, which are used in one implementation or another in color image-producing technology.

Additive primary colors

To form a color with RGB, three colored light beams (one red, one green, and one blue) must be superimposed (for example by emission from a black screen, or by reflection from a white screen). Each of the three beams is called a component of that color, and each of them can have an arbitrary intensity, from fully off to fully on, in the mixture.

The RGB color model is additive in the sense that the three light beams are added together, and their light spectra add, wavelength for wavelength, to make the final color's spectrum.

Zero intensity for each component gives the darkest color (no light, considered the black), and full intensity of each gives a white

White

White is a color, the perception of which is evoked by light that stimulates all three types of color sensitive cone cells in the human eye in nearly equal amounts and with high brightness compared to the surroundings. A white visual stimulation will be void of hue and grayness.White light can be...

; the quality of this white depends on the nature of the primary light sources, but if they are properly balanced, the result is a neutral white matching the system's white point

White point

A white point is a set of tristimulus values or chromaticity coordinates that serve to define the color "white" in image capture, encoding, or reproduction. Depending on the application, different definitions of white are needed to give acceptable results...

. When the intensities for all the components are the same, the result is a shade of gray, darker or lighter depending on the intensity. When the intensities are different, the result is a colorized hue

Hue

Hue is one of the main properties of a color, defined technically , as "the degree to which a stimulus can be describedas similar to or different from stimuli that are described as red, green, blue, and yellow,"...

, more or less saturated

Saturation (color theory)

In colorimetry and color theory, colorfulness, chroma, and saturation are related but distinct concepts referring to the perceived intensity of a specific color. Colorfulness is the degree of difference between a color and gray. Chroma is the colorfulness relative to the brightness of another color...

depending on the difference of the strongest and weakest of the intensities of the primary colors employed.

When one of the components has the strongest intensity, the color is a hue near this primary color (reddish, greenish, or bluish), and when two components have the same strongest intensity, then the color is a hue of a secondary color (a shade of cyan

Cyan

Cyan from , transliterated: kýanos, meaning "dark blue substance") may be used as the name of any of a number of colors in the blue/green range of the spectrum. In reference to the visible spectrum cyan is used to refer to the color obtained by mixing equal amounts of green and blue light or the...

, magenta

Magenta

Magenta is a color evoked by light stronger in blue and red wavelengths than in yellowish-green wavelengths . In light experiments, magenta can be produced by removing the lime-green wavelengths from white light...

or yellow

Yellow

Yellow is the color evoked by light that stimulates both the L and M cone cells of the retina about equally, with no significant stimulation of the S cone cells. Light with a wavelength of 570–590 nm is yellow, as is light with a suitable mixture of red and green...

). A secondary color is formed by the sum of two primary colors of equal intensity: cyan is green+blue, magenta is red+blue, and yellow is red+green. Every secondary color is the complement of one primary color; when a primary and its complementary secondary color are added together, the result is white: cyan complements red, magenta complements green, and yellow complements blue.

The RGB color model itself does not define what is meant by red, green, and blue colorimetrically, and so the results of mixing them are not specified as absolute, but relative to the primary colors. When the exact chromaticities

Chromaticity

Chromaticity is an objective specification of the quality of a color regardless of its luminance, that is, as determined by its hue and colorfulness ....

of the red, green, and blue primaries are defined, the color model then becomes an absolute color space

Absolute color space

In color science, there are two meanings of the term absolute color space:* A color space in which the perceptual difference between colors is directly related to distances between colors as represented by points in the color space....

, such as sRGB

SRGB color space

sRGB is a standard RGB color space created cooperatively by HP and Microsoft in 1996 for use on monitors, printers, and the Internet.sRGB uses the ITU-R BT.709 primaries, the same as are used in studio monitors and HDTV, and a transfer function typical of CRTs...

or Adobe RGB

Adobe RGB color space

The Adobe RGB color space is an RGB color space developed by Adobe Systems in 1998. It was designed to encompass most of the colors achievable on CMYK color printers, but by using RGB primary colors on a device such as the computer display...

; see RGB color spaces for more details.

Physical principles for the choice of red, green, and blue

The choice of primary colors is related to the physiology of the human eye

Human eye

The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...

; good primaries are stimuli that maximize the difference between the responses of the cone cells of the human retina to light of different wavelengths, and that thereby make a large color triangle

Color triangle

A color triangle is an arrangement of colors within a triangle, based on the additive combination of three primary colors at its corners.An additive color space defined by three primary colors has a chromaticity gamut that is a color triangle, when the amounts of the primaries are constrained to be...

.

The normal three kinds of light-sensitive photoreceptor cells in the human eye

Human eye

(cone cells) respond most to yellow (long wavelength or L), green (medium or M), and violet (short or S) light (peak wavelengths near 570 nm, 540 nm and 440 nm, respectively). The difference in the signals received from the three kinds allows the brain to differentiate a wide gamut

Gamut

In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain complete subset of colors. The most common usage refers to the subset of colors which can be accurately represented in a given circumstance, such as within a given color space or by a...

of different colors, while being most sensitive (overall) to yellowish-green light and to differences between hue

Hue

s in the green-to-orange region.

As an example, suppose that light in the orange range of wavelengths (approximately 577 nm to 597 nm) enters the eye and strikes the retina. Light of these wavelengths would activate both the medium and long wavelength cones of the retina, but not equally—the long-wavelength cells will respond more. The difference in the response can be detected by the brain and associated with the concept that the light is orange. In this sense, the orange appearance of objects is simply the result of light from the object entering our eye and stimulating the relevant kinds of cones simultaneously but to different degrees.

Use of the three primary colors is not sufficient to reproduce all colors; only colors within the color triangle

Color triangle

defined by the chromaticities

Chromaticity

Chromaticity is an objective specification of the quality of a color regardless of its luminance, that is, as determined by its hue and colorfulness ....

of the primaries can be reproduced by additive mixing of non-negative amounts of those colors of light.

History of RGB color model theory and usage

The RGB color model is based on the Young–Helmholtz theory of trichromatic color vision, developed by Thomas Young

Thomas Young (scientist)

Thomas Young was an English polymath. He is famous for having partly deciphered Egyptian hieroglyphics before Jean-François Champollion eventually expanded on his work...

and Hermann Helmholtz, in the early to mid nineteenth century, and on James Clerk Maxwell

James Clerk Maxwell

James Clerk Maxwell of Glenlair was a Scottish physicist and mathematician. His most prominent achievement was formulating classical electromagnetic theory. This united all previously unrelated observations, experiments and equations of electricity, magnetism and optics into a consistent theory...

's color triangle

Color triangle

that elaborated that theory (circa 1860).

Photography

First experiments with RGB in early color photography

Color photography

Color photography is photography that uses media capable of representing colors, which are traditionally produced chemically during the photographic processing phase...

were made in 1861 by Maxwell himself, and involved the process of three color-filtered separate takes. To reproduce the color photograph, three matching projections over a screen in a dark room were necessary.

The additive RGB model and variants such as orange–green–violet were also used in the Autochrome Lumière

Autochrome Lumière

The Autochrome Lumière is an early color photography process. Patented in 1903 by the Lumière brothers in France and first marketed in 1907, it was the principal color photography process in use before the advent of subtractive color film in the mid-1930s....

color plates and other screen-plate technologies such as the Joly color screen

Joly Color Screen

The Joly Color process is an early additive color photography process devised by Dublin physicist John Joly in 1894.-Description:Based on a method proposed in 1869 by Louis Ducos du Hauron in Les Couleurs en Photographie - Solution du Probleme, the Joly Color process used a glass photographic plate...

and the Paget process

Paget process

The Paget process was an early colour photography process patented in Britain in 1912 by G.S. Whitfield and first marketed by the Paget Prize Plate Company in 1913. A paper-based Paget process was also briefly sold. Both were discontinued in the early 1920s...

in the early twentieth century. Color photography by taking three separate plates was used by other pioneers, such as Russian Sergey Prokudin-Gorsky in the period 1909 through 1915.Photographer to the Tsar: Sergei Mikhailovich Prokudin-Gorskii Library of Congress. Such methods last until about 1960 using the expensive and extremely complex tri-color carbro

Carbon print

A carbon print is a photographic print with an image consisting of pigmented gelatin, rather than of silver or other metallic particles suspended in a uniform layer of gelatin, as in typical black-and-white prints, or of chromogenic dyes, as in typical photographic color prints.In the original...

Autotype

Autotype is a function in some computer applications or programs, typically those containing forms, which fills in a field once you have typed in the first few letters...

process.

When employed, the reproduction of prints from three-plate photos was done by dyes or pigments using the complementary CMY

CMYK color model

model, by simply using the negative plates of the filtered takes: reverse red gives the cyan plate, and so on.

Television

Before the development of practical electronic TV, there were patents on mechanically scanned color systems as early as 1889 in Russia

Russian Empire

The Russian Empire was a state that existed from 1721 until the Russian Revolution of 1917. It was the successor to the Tsardom of Russia and the predecessor of the Soviet Union...

. The color TV

Color television

Color television is part of the history of television, the technology of television and practices associated with television's transmission of moving images in color video....

pioneer John Logie Baird

John Logie Baird

John Logie Baird FRSE was a Scottish engineer and inventor of the world's first practical, publicly demonstrated television system, and also the world's first fully electronic colour television tube...

demonstrated the world's first RGB color transmission in 1928, and also the world's first color broadcast in 1938, in London

London

London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

. In his experiments, scanning and display were done mechanically by spinning colorized wheels.

The Columbia Broadcasting System (CBS)

CBS

CBS Broadcasting Inc. is a major US commercial broadcasting television network, which started as a radio network. The name is derived from the initials of the network's former name, Columbia Broadcasting System. The network is sometimes referred to as the "Eye Network" in reference to the shape of...

began an experimental RGB field-sequential color system

Field-sequential color system

A field-sequential color system is a color television system in which the primary color information is transmitted in successive images, and which relies on the human vision system to fuse the successive images into a color picture. One field-sequential system was developed by Dr. Peter Goldmark...

in 1940. Images were scanned electrically, but the system still used a moving part: the transparent RGB color wheel rotating at above 1,200 rpm in synchronism with the vertical scan. The camera and the cathode-ray tube (CRT) were both monochromatic. Color was provided by color wheels in the camera and the receiver.
More recently, color wheels have been used in field-sequential projection TV receivers based on the Texas Instruments monochrome DLP imager.

The modern RGB shadow mask

Shadow mask

The shadow mask is one of two major technologies used to manufacture cathode ray tube televisions and computer displays that produce color images. The other approach is aperture grille, better known by its trade name, Trinitron. All early color televisions and the majority of CRT computer monitors...

technology for color CRT displays was patented by Werner Flechsig in Germany in 1938.

Personal computers

Early personal computer

Personal computer

A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...

s of the late 1970s and early 1980s, such as those from Apple

Apple II series

The Apple II series is a set of 8-bit home computers, one of the first highly successful mass-produced microcomputer products, designed primarily by Steve Wozniak, manufactured by Apple Computer and introduced in 1977 with the original Apple II...

, Atari

Atari 8-bit family

The Atari 8-bit family is a series of 8-bit home computers manufactured from 1979 to 1992. All are based on the MOS Technology 6502 CPU and were the first home computers designed with custom coprocessor chips...

and Commodore

Commodore VIC-20

The VIC-20 is an 8-bit home computer which was sold by Commodore Business Machines. The VIC-20 was announced in 1980, roughly three years after Commodore's first personal computer, the PET...

, did not use RGB as their main method to manage colors, but rather composite video

Composite video

Composite video is the format of an analog television signal before it is combined with a sound signal and modulated onto an RF carrier. In contrast to component video it contains all required video information, including colors in a single line-level signal...

. IBM

IBM

International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...

introduced a 16-color scheme (one bit each for RGB and Intensity) with the Color Graphics Adapter

Color Graphics Adapter

The Color Graphics Adapter , originally also called the Color/Graphics Adapter or IBM Color/Graphics Monitor Adapter, introduced in 1981, was IBM's first color graphics card, and the first color computer display standard for the IBM PC....

(CGA) for its first IBM PC

IBM PC

The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12, 1981...

(1981), later improved with the Enhanced Graphics Adapter

Enhanced Graphics Adapter

The Enhanced Graphics Adapter is the IBM PC computer display standard specification which is between CGA and VGA in terms of color and space resolution. Introduced in October 1984 by IBM shortly after its new PC/AT, EGA produces a display of 16 simultaneous colors from a palette of 64 at a...

(EGA) in 1984. The first manufacturer of a truecolor graphic card for PCs (the TARGA) was Truevision

Truevision

Truevision, Inc. was a maker of digital video processing add-on boards for PC computers. It was founded by Cathleen Asch, Carl Calabria, Joseph Haaf, Bryan Hunt, Brad Pillow, Joe Shepard and Jeff Walters and others when AT&T split off their Electronic Photography and Imaging Center in 1987...

in 1987, but it was not until the arrival of the Video Graphics Array

Video Graphics Array

Video Graphics Array refers specifically to the display hardware first introduced with the IBM PS/2 line of computers in 1987, but through its widespread adoption has also come to mean either an analog computer display standard, the 15-pin D-subminiature VGA connector or the 640×480 resolution...

(VGA) in 1987 that RGB became popular, mainly due to the analog signal

Analog signal

An analog or analogue signal is any continuous signal for which the time varying feature of the signal is a representation of some other time varying quantity, i.e., analogous to another time varying signal. It differs from a digital signal in terms of small fluctuations in the signal which are...

s in the connection between the adapter and the monitor

Computer display

A monitor or display is an electronic visual display for computers. The monitor comprises the display device, circuitry, and an enclosure...

which allowed a very wide range of RGB colors.

RGB and displays

One common application of the RGB color model is the display of colors on a cathode ray tube

Cathode ray tube

(CRT), liquid crystal display

Liquid crystal display

A liquid crystal display is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals . LCs do not emit light directly....

(LCD), plasma display

Plasma display

, or LED display

LEd

LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....

such as a television, a computer’s monitor, or a large scale screen. Each pixel

Pixel

In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....

on the screen is built by driving three small and very close but still separated RGB light sources. At common viewing distance, the separate sources are indistinguishable, which tricks the eye to see a given solid color. All the pixels together arranged in the rectangular screen surface conforms the color image.

During digital image processing

Digital image processing

Digital image processing is the use of computer algorithms to perform image processing on digital images. As a subcategory or field of digital signal processing, digital image processing has many advantages over analog image processing...

each pixel can be represented in the computer memory

Computer memory

In computing, memory refers to the physical devices used to store programs or data on a temporary or permanent basis for use in a computer or other digital electronic device. The term primary memory is used for the information in physical systems which are fast In computing, memory refers to the...

or interface hardware (for example, a graphics card) as binary

Binary numeral system

The binary numeral system, or base-2 number system, represents numeric values using two symbols, 0 and 1. More specifically, the usual base-2 system is a positional notation with a radix of 2...

values for the red, green, and blue color components. When properly managed, these values are converted into intensities or voltages via gamma correction

Gamma correction

Gamma correction, gamma nonlinearity, gamma encoding, or often simply gamma, is the name of a nonlinear operation used to code and decode luminance or tristimulus values in video or still image systems...

to correct the inherent nonlinearity of some devices, such that the intended intensities are reproduced on the display.

The Quattron

Quattron

Quattron is the brand name of an LCD color display technology produced by Sharp Electronics. The technology utilizes a fourth color subpixel, yellow, in addition to the standard RGB color subpixels, which Sharp claims increases the range of displayable colors, and which may mimic more closely the...

released by Sharp uses RGB color and adds yellow as a sub-pixel, supposedly allowing an increase in the number of available colors.

Video electronics

RGB is also the term referring to a type of component video

Component video

Component video is a video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video information that is transmitted or stored as three separate signals...

signal used in the video

Video

Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...

electronics industry. It consists of three signals—red, green, and blue—carried on three separate cables/pins. Extra cables are sometimes needed to carry synchronizing signals. RGB signal formats are often based on modified versions of the RS-170 and RS-343 standards for monochrome video. This type of video signal is widely used in Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

since it is the best quality signal that can be carried on the standard SCART

SCART

SCART is a French-originated standard and associated 21-pin connector for connecting audio-visual equipment together...

connector. This signal is known as RGBS (4 BNC

BNC connector

The BNC connector ' is a common type of RF connector used for coaxial cable. It is used with radio, television, and other radio-frequency electronic equipment, test instruments, video signals, and was once a popular computer network connector. BNC connectors are made to match the characteristic...

/RCA

RCA

RCA Corporation, founded as the Radio Corporation of America, was an American electronics company in existence from 1919 to 1986. The RCA trademark is currently owned by the French conglomerate Technicolor SA through RCA Trademark Management S.A., a company owned by Technicolor...

terminated cables exist as well), but it's not directly compatible with RGBHV used for computer monitors (usually carried on 15-pin cables terminated with 15-pin D-sub or 5 BNC connector

BNC connector

s), which carries separate horizontal and vertical sync signals. There exist integrated circuits that decode the composite sync signal into vertical and horizontal components, for instance the LM1881. The newer LMH1980 and LMH1981 are advertised as supporting composite RGB sync separation. They require fewer additional circuitry, and by auto-detecting the video format can be used for separating the sync components in other types of component video

Component video

with the same circuit.

Outside Europe, RGB is not very popular as a video signal format; S-Video

S-Video

Separate Video, more commonly known as S-Video and Y/C, is often referred to by JVC as both an S-VHS connector and as Super Video. It is an analog video transmission scheme, in which video information is encoded on two channels: luma and chroma...

takes that spot in most non-European regions. However, almost all computer monitors around the world use RGB.

Video framebuffer

A framebuffer

Framebuffer

A framebuffer is a video output device that drives a video display from a memory buffer containing a complete frame of data.The information in the memory buffer typically consists of color values for every pixel on the screen...

is a digital device for computers which stores data in the so-called video memory (comprising an array of Video RAM or similar chips

Integrated circuit

An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...

). This data goes either to three digital-to-analog converters (DACs) (for analog monitors), one per primary color, or directly to digital monitors. Driven by software, the CPU

Central processing unit

The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...

(or other specialized chips) write the appropriate byte

Byte

The byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer...

s into the video memory to define the image. Modern systems encode pixel color values by devoting eight bit

Bit

A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...

s to each of the R, G, and B components. RGB information can be either carried directly by the pixel bits themselves, or provided by a separate Color Look-Up Table (CLUT) if indexed color

Indexed color

In computing, indexed color is a technique to manage digital images' colors in a limited fashion, in order to save computer memory and file storage, while speeding up display refresh and file transfers...

graphic modes are used.

A CLUT is a specialized RAM

Ram

-Animals:*Ram, an uncastrated male sheep*Ram cichlid, a species of freshwater fish endemic to Colombia and Venezuela-Military:*Battering ram*Ramming, a military tactic in which one vehicle runs into another...

that stores R, G, and B values that define specific colors. Each color has its own address (index) -- consider it as a descriptive reference number that provides that specific color when the image needs it. The content of the CLUT is much like a palette of colors. Image data that uses indexed color specifies addresses within the CLUT to provide the required R, G, and B values for each specific pixel, one pixel at a time. Of course, before displaying, the CLUT has to be loaded with R, G, and B values that define the palette of colors required for each image to be rendered.

This indirect scheme restricts the number of available colors in an image (typically 256), although each color in the table has typically 8 bits for each of the R, G, and B primaries. This means that any given color can be one of approx. 16.7 million possible colors. However, the advantage is that an indexed-color image file can be significantly smaller than it would be with 8 bits per pixel for each primary. Modern storage, however, is far less costly, greatly reducing the need to minimize image file size.

By using an appropriate combination of red, green, and blue intensities, many colors can be displayed. Current typical display adapters use up to 24-bit

24-bit

Notable 24-bit machines include the ICT 1900 series and the Harris H series.The IBM System/360, announced in 1964, was a popular computer system with 24-bit addressing and 32-bit general registers and arithmetic...

s of information for each pixel: 8-bit per component multiplied by three components (see the Digital representations section below). With this system, 16,777,216 (256³ or 2²⁴) discrete combinations of R, G and B values are allowed, providing millions of different (though not necessarily distinguishable) hue

Hue

, saturation

Saturation (color theory)

, and lightness

Lightness (color)

Lightness is a property of a color, or a dimension of a color space, that is defined in a way to reflect the subjective brightness perception of a color for humans along a lightness–darkness axis. A color's lightness also corresponds to its amplitude.Various color models have an explicit term for...

shades.

For images with a modest range of brightnesses from the darkest to the lightest, eight bits per primary color provides good-quality images, but extreme images require more bits per primary color as well as advanced display technology. For more information see High Dynamic Range

High dynamic range

High dynamic range is a term generally used for media applications such as digital imaging and digital audio production...

(HDR) imaging.

Nonlinearity

In classic cathode ray tube

Cathode ray tube

(CRT) devices, the brightness of a given point over the fluorescent screen due to the impact of accelerated electron

Electron

The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...

s is not proportional to the voltages applied to the electron gun

Electron gun

An electron gun is an electrical component that produces an electron beam that has a precise kinetic energy and is most often used in television sets and computer displays which use cathode ray tube technology, as well as in other instruments, such as electron microscopes and particle...

control grids, but to an expansive function of that voltage. The amount of this deviation is known as its gamma

Gamma correction

value (

), the argument for a power law

Power law

A power law is a special kind of mathematical relationship between two quantities. When the frequency of an event varies as a power of some attribute of that event , the frequency is said to follow a power law. For instance, the number of cities having a certain population size is found to vary...

function, which closely describes this behaviour. A linear response is given by a gamma value of 1.0, but actual CRT nonlinearities have a gamma value around 2.0 to 2.5.

Similarly, the intensity of the output on TV and computer display devices is not directly proportional to the R, G, and B applied electric signals (or file data values which drive them through Digital-to-Analog Converter

Digital-to-analog converter

In electronics, a digital-to-analog converter is a device that converts a digital code to an analog signal . An analog-to-digital converter performs the reverse operation...

s). On a typical standard 2.2-gamma CRT display, an input intensity RGB value of (0.5, 0.5, 0.5) only outputs about 22% of full brightness (1.0, 1.0, 1.0), instead of 50%. To obtain the correct response, a gamma correction

Gamma correction

is used in encoding the image data, and possibly further corrections as part of the color calibration

Color calibration

The aim of color calibration is to measure and/or adjust the color response of a device to a known state. In ICC terms this is the basis for a additional color characterization of the device and later profiling. In non ICC workflows calibration refers sometimes to establishing a known relationship...

process of the device. Gamma affects black-and-white

Black-and-white

Black-and-white, often abbreviated B/W or B&W, is a term referring to a number of monochrome forms in visual arts.Black-and-white as a description is also something of a misnomer, for in addition to black and white, most of these media included varying shades of gray...

TV as well as color. In standard color TV, broadcast signals are gamma corrected.

Display technologies different from CRTs, such as LCD, plasma, LED, etc. may behave nonlinearly in different ways. When they are intended to display standard TV and video, their gamma is set equivalent to a CRT TV monitor. In digital image processing, gamma correction can be applied either by the hardware or by the software packages used.

Other input/output RGB devices may also have nonlinear responses, depending on the technology employed. In any case, nonlinearity (whether gamma-related or not) is not part of the RGB color model in itself, although different standards that use RGB can also specify the gamma value and/or other nonlinear parameters involved.

RGB and cameras

In color television and video camera

Professional video camera

A professional video camera is a high-end device for creating electronic moving images...

s manufactured before the 1990s, the incoming light was separated by prism

Prism (optics)

In optics, a prism is a transparent optical element with flat, polished surfaces that refract light. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a triangular prism with a triangular base and rectangular sides, and in colloquial use...

s and filters into the three RGB primary colors feeding each color into a separate video camera tube

Video camera tube

In older video cameras, before the mid to late 1980s, a video camera tube or pickup tube was used instead of a charge-coupled device for converting an optical image into an electrical signal. Several types were in use from the 1930s to the 1980s...

(or pickup tube). These tubes are a type of cathode ray tube, not to be confused with that of CRT displays.

With the arrival of commercially viable charge-coupled device

Charge-coupled device

A charge-coupled device is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated, for example conversion into a digital value. This is achieved by "shifting" the signals between stages within the device one at a time...

(CCD) technology in the 1980s, first the pickup tubes were replaced with this kind of sensors. Later, higher scale integration electronics was applied (mainly by Sony

Sony

, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....

), simplifying and even removing the intermediate opticals, up to a point to reduce the size of video camera

Video camera

A video camera is a camera used for electronic motion picture acquisition, initially developed by the television industry but now common in other applications as well. The earliest video cameras were those of John Logie Baird, based on the electromechanical Nipkow disk and used by the BBC in...

s for domestic use until convert them in handy and full camcorder

Camcorder

A camcorder is an electronic device that combines a video camera and a video recorder into one unit. Equipment manufacturers do not seem to have strict guidelines for the term usage...

s. Current webcam

Webcam

A webcam is a video camera that feeds its images in real time to a computer or computer network, often via USB, ethernet, or Wi-Fi.Their most popular use is the establishment of video links, permitting computers to act as videophones or videoconference stations. This common use as a video camera...

s and mobile phone

Mobile phone

s with cameras are the most miniaturized commercial forms of such technology.

Photographic digital camera

Digital camera

s that use a CMOS

CMOS

Complementary metal–oxide–semiconductor is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits...

or CCD image sensor

Image sensor

An image sensor is a device that converts an optical image into an electronic signal. It is used mostly in digital cameras and other imaging devices...

often operate with some variation of the RGB model. In a Bayer filter

Bayer filter

A Bayer filter mosaic is a color filter array for arranging RGB color filters on a square grid of photosensors. Its particular arrangement of color filters is used in most single-chip digital image sensors used in digital cameras, camcorders, and scanners to create a color image...

arrangement, green is given twice as many detectors as red and blue (ratio 1:2:1) in order to achieve higher luminance

Luminance

Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle. The SI unit for luminance is candela per square...

resolution than chrominance

Chrominance

Chrominance is the signal used in video systems to convey the color information of the picture, separately from the accompanying luma signal . Chrominance is usually represented as two color-difference components: U = B' − Y' and V = R' − Y'...

resolution. The sensor has a grid of red, green, and blue detectors arranged so that the first row is RGRGRGRG, the next is GBGBGBGB, and that sequence is repeated in subsequent rows. For every channel, missing pixels are obtained by interpolation

Interpolation

In the mathematical field of numerical analysis, interpolation is a method of constructing new data points within the range of a discrete set of known data points....

in the demosaicing

Demosaicing

A demosaicing algorithm is a digital image process used to reconstruct a full color image from the incomplete color samples output from an image sensor overlaid with a color filter array...

process to build up the complete image. Also, other processes used to be applied in order to map the camera RGB measurements into a standard RGB color space

RGB color space

An RGB color space is any additive color space based on the RGB color model. A particular RGB color space is defined by the three chromaticities of the red, green, and blue additive primaries, and can produce any chromaticity that is the triangle defined by those primary colors...

as sRGB.

RGB and scanners

In computing, an image scanner

Image scanner

is a device that optically scans images (printed text, handwriting, or an object) and converts it to a digital image which is transferred to a computer. Among other formats, flat, drum, and film scanners exist, and most of them support RGB color. They can be considered the successors of early telephotography input devices, which were able to send consecutive scan line

Scan line

A scan line or scanline is one line, or row, in a raster scanning pattern, such as a line of video on a cathode ray tube display of a television set or computer monitor....

s as analog

Analog signal

amplitude modulation

Amplitude modulation

Amplitude modulation is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. AM works by varying the strength of the transmitted signal in relation to the information being sent...

signals through standard telephonic lines to appropriate receivers; such systems were in use in press

Publishing

Publishing is the process of production and dissemination of literature or information—the activity of making information available to the general public...

since the 1920s to the mid 1990s. Color telephotographs were sent as three separated RGB filtered images consecutively.

Currently available scanners typically use charge-coupled device

Charge-coupled device

(CCD) or contact image sensor

Contact Image Sensor

Contact Image Sensors are a relatively recent technological innovation in the field of optical flatbed scanners that are rapidly replacing CCDs in low power and portable applications...

(CIS) as the image sensor, whereas older drum scanners use a photomultiplier tube

Photomultiplier

Photomultiplier tubes , members of the class of vacuum tubes, and more specifically phototubes, are extremely sensitive detectors of light in the ultraviolet, visible, and near-infrared ranges of the electromagnetic spectrum...

as the image sensor. Early color film scanners used a halogen lamp

Halogen lamp

A halogen lamp, also known as a tungsten halogen lamp, is an incandescent lamp with a tungsten filament contained within an inert gas and a small amount of a halogen such as iodine or bromine. The chemical halogen cycle redeposits evaporated tungsten back on to the filament, extending the life of...

and a three-color filter wheel, so three exposures were needed to scan a single color image. Due to heating problems, the worst of them being the potential destruction of the scanned film, this technology was later replaced by non-heating light sources such as color LED

LEd

LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....

Numeric representations

A color in the RGB color model is described by indicating how much of each of the red, green, and blue is included. The color is expressed as an RGB triplet (r,g,b), each component of which can vary from zero to a defined maximum value. If all the components are at zero the result is black; if all are at maximum, the result is the brightest representable white.

These ranges may be quantified in several different ways:

From 0 to 1, with any fractional value in between. This representation is used in theoretical analyses, and in systems that use floating-point representations.
Each color component value can also be written as a percentage
Percentage
In mathematics, a percentage is a way of expressing a number as a fraction of 100 . It is often denoted using the percent sign, “%”, or the abbreviation “pct”. For example, 45% is equal to 45/100, or 0.45.Percentages are used to express how large/small one quantity is, relative to another quantity...

, from 0% to 100%.
In computing, the component values are often stored as integer
Integer
The integers are formed by the natural numbers together with the negatives of the non-zero natural numbers .They are known as Positive and Negative Integers respectively...

numbers in the range 0 to 255, the range that a single 8-bit byte
Byte
The byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer...

can offer (by encoding 256 distinct values). These may be represented as either decimal or hexadecimal
Hexadecimal
In mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...

numbers.
High-end digital image equipment can deal with the integer range 0 to 65,535 for each primary color, by employing 16-bit
16-bit
-16-bit architecture:The HP BPC, introduced in 1975, was the world's first 16-bit microprocessor. Prominent 16-bit processors include the PDP-11, Intel 8086, Intel 80286 and the WDC 65C816. The Intel 8088 was program-compatible with the Intel 8086, and was 16-bit in that its registers were 16...

words instead of 8-bit bytes.

For example, brightest saturated red is written in the different RGB notations as:

{| class="wikitable"

! Notation
! RGB triplet
|-
| Arithmetic
| (1.0, 0.0, 0.0)
|-
| Percentage
| (100%, 0%, 0%)
|-
| Digital 8-bit per channel
| (255, 0, 0) or sometimes
#FF0000 (hexadecimal)
|-
| Digital 16-bit per channel
| (65535, 0, 0)
|}

In many environments, the component values within the ranges are not managed as linear (that is, the numbers are nonlinearly related to the intensities that they represent), as in digital camera

Digital camera

s and TV broadcasting and receiving due to gamma correction

Gamma correction

, for example. Linear and nonlinear transformations are often dealt with via digital image processing

Digital image processing

. Representations with only 8 bits per component are considered sufficient if gamma encoding is used.

Color depth

The RGB color model is the most common way to encode color in computing, and several different binary

Binary numeral system

The binary numeral system, or base-2 number system, represents numeric values using two symbols, 0 and 1. More specifically, the usual base-2 system is a positional notation with a radix of 2...

digital

Digital

A digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...

representations are in use. The main characteristic of all of them is the quantization

Quantization (signal processing)

Quantization, in mathematics and digital signal processing, is the process of mapping a large set of input values to a smaller set – such as rounding values to some unit of precision. A device or algorithmic function that performs quantization is called a quantizer. The error introduced by...

of the possible values per component (technically a Sample (signal) ) by using only integer

Integer

The integers are formed by the natural numbers together with the negatives of the non-zero natural numbers .They are known as Positive and Negative Integers respectively...

numbers within some range, usually from 0 to some power of two minus one (2ⁿ – 1) to fit them into some bit

Bit

groupings. Encodings of 1, 2, 4, 5, 8, and 16 bits per color are commonly found; the total number of bits used for an RGB color is typically called the color depth

Color depth

In computer graphics, color depth or bit depth is the number of bits used to represent the color of a single pixel in a bitmapped image or video frame buffer. This concept is also known as bits per pixel , particularly when specified along with the number of bits used...

Geometric representation

See also RGB color space
RGB color space
An RGB color space is any additive color space based on the RGB color model. A particular RGB color space is defined by the three chromaticities of the red, green, and blue additive primaries, and can produce any chromaticity that is the triangle defined by those primary colors...

Since colors are usually defined by three components, not only in the RGB model, but also in other color models such as CIELAB

Lab color space

A Lab color space is a color-opponent space with dimension L for lightness and a and b for the color-opponent dimensions, based on nonlinearly compressed CIE XYZ color space coordinates....

and Y'UV, among others, then a three-dimensional

Three-dimensional space

Three-dimensional space is a geometric 3-parameters model of the physical universe in which we live. These three dimensions are commonly called length, width, and depth , although any three directions can be chosen, provided that they do not lie in the same plane.In physics and mathematics, a...

volume

Volume

Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance or shape occupies or contains....

is described by treating the component values as ordinary cartesian coordinates

Cartesian coordinate system

A Cartesian coordinate system specifies each point uniquely in a plane by a pair of numerical coordinates, which are the signed distances from the point to two fixed perpendicular directed lines, measured in the same unit of length...

in a euclidean space

Euclidean space

In mathematics, Euclidean space is the Euclidean plane and three-dimensional space of Euclidean geometry, as well as the generalizations of these notions to higher dimensions...

. For the RGB model, this is represented by a cube using non-negative values within a 0–1 range, assigning black to the origin at the vertex (0, 0, 0), and with increasing intensity values running along the three axes up to white at the vertex (1, 1, 1), diagonally opposite black.

An RGB triplet (r,g,b) represents the three-dimensional coordinate of the point of the given color within the cube or its faces or along its edges. This approach allows computations of the color similarity

Color difference

The difference or distance between two colors is a metric of interest in color science. It allows people to quantify a notion that would otherwise be described with adjectives, to the detriment of anyone whose work is color critical...

of two given RGB colors by simply calculating the distance

Euclidean distance

In mathematics, the Euclidean distance or Euclidean metric is the "ordinary" distance between two points that one would measure with a ruler, and is given by the Pythagorean formula. By using this formula as distance, Euclidean space becomes a metric space...

between them: the shorter the distance, the higher the similarity. Out-of-gamut

Gamut

computations can also be performed this way.

Colors in web-page design

Colors used in web-page design are commonly specified using RGB; see web colors

Web colors

Web colors are colors used in designing web pages, and the methods for describing and specifying those colors. Hexadecimal color codes begin with a hash ....

for an explanation of how colors are used in HTML

HTML

HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....

and related languages. Initially, the limited color depth

Color depth

of most video hardware led to a limited color palette of 216 RGB colors, defined by the Netscape Color Cube. However, with the predominance of 24-bit displays, the use of the full 16.7 million colors of the HTML RGB color code no longer poses problems for most viewers.

In short, the web-safe color palette consists of the 216 (6³) combinations of red, green, and blue where each color can take one of six values (in hexadecimal

Hexadecimal

In mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...

): #00, #33, #66, #99, #CC or #FF (based on the 0 to 255 range for each value discussed above). These hexadecimal values = 0, 51, 102, 153, 204, 255 in decimal, which = 0%, 20%, 40%, 60%, 80%, 100% in terms of intensity. This seems fine for splitting up 216 colors into a cube of dimension 6. However, lacking gamma correction

Gamma correction

, the perceived intensity on a standard 2.5 gamma CRT / LCD is only: 0%, 2%, 10%, 28%, 57%, 100%. See the actual web safe color palette for a visual confirmation that the majority of the colors produced are very dark, or see Xona.com Color List for a side by side comparison of proper colors next to their equivalent lacking proper gamma correction.

The RGB color model for HTML was formally adopted as an Internet standard in HTML 3.2, however it had been in use for some time before that.

Color management

Proper reproduction of colors, especially in professional environments, requires color management of all the devices involved in the production process, many of them using RGB. Color management results in several transparent conversions between device-independent and device-dependent color space

Color space

A color model is an abstract mathematical model describing the way colors can be represented as tuples of numbers, typically as three or four values or color components...

s (RGB and others, as CMYK

CMYK color model

for color printing) during a typical production cycle, in order to ensure color consistency throughout the process. Along with the creative processing, such interventions on digital images can damage the color accuracy and image detail, especially where the gamut

Gamut

is reduced. Professional digital devices and software tools allow for 48 bpp (bits per pixel) images to be manipulated (16 bits per channel), to minimize any such damage.

ICC-compliant applications, such as Adobe Photoshop

Adobe Photoshop

Adobe Photoshop is a graphics editing program developed and published by Adobe Systems Incorporated.Adobe's 2003 "Creative Suite" rebranding led to Adobe Photoshop 8's renaming to Adobe Photoshop CS. Thus, Adobe Photoshop CS5 is the 12th major release of Adobe Photoshop...

, use either the Lab color space

Lab color space

A Lab color space is a color-opponent space with dimension L for lightness and a and b for the color-opponent dimensions, based on nonlinearly compressed CIE XYZ color space coordinates....

or the CIE 1931 color space

CIE 1931 color space

In the study of color perception, one of the first mathematically defined color spaces is the CIE 1931 XYZ color space, created by the International Commission on Illumination in 1931....

as a Profile Connection Space when translating between color spaces.

RGB model and luminance–chrominance formats relationship

All luminance–chrominance

Chrominance

formats used in the different TV and video standards such as YIQ

YIQ

YIQ is the color space used by the NTSC color TV system, employed mainly in North and Central America, and Japan. It is currently in use only for low-power television stations, as full-power analog transmission was ended by the U.S. Federal Communications Commission on 12 June 2009...

for NTSC

NTSC

NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...

, YUV

YUV

YUV is a color space typically used as part of a color image pipeline. It encodes a color image or video taking human perception into account, allowing reduced bandwidth for chrominance components, thereby typically enabling transmission errors or compression artifacts to be more efficiently...

for PAL

PAL

PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...

, YD_BD_R

YDbDr

YDbDr, sometimes written YDBDR, is the colour space used in the SÉCAM analog terrestrial colour television broadcasting standard, which is used in France and some countries of the former Eastern Bloc. It is very close to YUV and its related colour spaces such as YIQ , YPbPr and YCbCr.YDbDr is...

for SECAM

SECAM

SECAM, also written SÉCAM , is an analog color television system first used in France....

, and YP_BP_R

YPbPr

' is a color space used in video electronics, in particular in reference to component video cables. is the analog version of the YCBCR color space; the two are numerically equivalent, but YPBPR is designed for use in analog systems whereas YCBCR is intended for digital video. cables are also...

for component video

Component video

use color difference signals, by which RGB color images can be encoded for broadcasting/recording and later decoded into RGB again to display them. These intermediate formats were needed for compatibility with pre-existent black-and-white TV formats. Also, those color difference signals need lower data bandwidth compared to full RGB signals.

Similarly, current high-efficiency digital color image data compression

Data compression

In computer science and information theory, data compression, source coding or bit-rate reduction is the process of encoding information using fewer bits than the original representation would use....

schemes such as JPEG

JPEG

In computing, JPEG . The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality....

and MPEG store RGB color internally in YC_BC_R

YCbCr

YCbCr or Y′CbCr, sometimes written or , is a family of color spaces used as a part of the color image pipeline in video and digital photography systems. Y′ is the luma component and CB and CR are the blue-difference and red-difference chroma components...

format, a digital luminance-chrominance format based on YP_BP_R. The use of YC_BC_R also allows to perform lossy subsampling

Chroma subsampling

Chroma subsampling is the practice of encoding images by implementing less resolution for chroma information than for luma information, taking advantage of the human visual system's lower acuity for color differences than for luminance....

with the chroma channels (typically to 4:2:2 or 4:1:1 ratios), which it aids to reduce the resultant file size.

External links

Demonstrative color conversion applet

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.