A representation of additive color mixing. Projection of primary color lights on a screen shows secondary colors where two overlap; the combination of all three of red, green, and blue in appropriate intensities makes white. Primary colors are sets of Colors that can be combined to make a useful range ( Gamut) of colors

An RGB image, along with its separate R, G and B components; Note that the white snow consists of strong red, green, and blue; the brown barn is composed of strong red and green with little blue; the dark green grass consists of strong green with little red or blue; and the light blue sky is composed of strong blue and moderately strong red and green.

The RGB color model is an additive color model in which red, green, and blue light are added together in various ways to reproduce a broad array of colors. An additive color model involves Light emitted directly from a source or illuminant of some sort 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 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- nm. Blue is a Colour, the Perception of which is evoked by The name of the model comes from the initials of the three additive primary colors, red, green, and blue. Primary colors are sets of Colors that can be combined to make a useful range ( Gamut) of colors

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 (fә'tɒgrәfi or fә'tɑːgrәfi (from Greek φωτο and γραφία is the process and Art of recording pictures by means of capturing Before the electronic age, the RGB color model already had a solid theory behind it, based in human perception of colors. Trichromacy is the condition of possessing three independent channels for conveying Color information derived from the three different cone types

RGB is a device-dependent color space: 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. In digital imaging systems color management is the controlled conversion between the Color representations of various devices such as Image scanners Digital

Typical RGB input devices are color TV and video cameras, image scanners, and digital cameras. A professional Video camera (often called a television camera even though the use has spread is a high-end device for recording electronic moving images (as opposed Historical precedent Scanners can be considered the successors of early telephotography input devices consisting of a rotating drum with a single Photodetector at Many compact digital still cameras can record Sound and moving Video as well as still Photograph. Typical RGB output devices are TV sets of various technologies (CRT, LCD, plasma, etc. The cathode ray tube (CRT is a Vacuum tube containing an Electron gun (a source of electrons and a Fluorescent screen with internal or Liquid-crystal display televisions ( LCD TV) are Television sets that use LCD technology to produce images A plasma display panel (PDP is a type of Flat panel display now commonly used for large TV displays (typically above 37-inch or 940 mm ), computer and mobile phone displays, video projectors, multicolor LED displays, and large screens as JumboTron, etc. A visual display unit, often called simply a monitor or display, is a piece of Electrical equipment which displays images generated from the Video A video projector takes a Video signal and projects the corresponding image on a Projection screen using a lens system A JumboTron is a Large-screen television technology developed by Sony, typically used in Sports stadiums and concert venues to show close up shots of the Color printers, on the other hand, are usually not RGB devices, but subtractive color devices (typically CMYK color model). A subtractive color model explains the mixing of Paints Dyes Inks and natural colorants to create a range of Colors where each such color CMYK (short for '''c'''yan, '''m'''agenta, '''y'''ellow, and k ey ( Black) and often referred to as process color

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 beam are added together, and their light spectra add, wavelength for wavelength, to make the final color's spectrum. ^[1][2]

Zero intensity for each component gives the darkest color (no light, considered the black), and full intensity of each gives a white; 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 is a Color, the perception which is evoked by Light that stimulates all three types of color sensitive Cone cells in the Human eye A white point (often referred to as reference white or target white in technical documents is a set of tristimulus values or Chromaticity coordinates 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, more or less saturated depending on the difference of the strongest and weakest of the intensities of the primary colors employed. Hue is one of the main properties of a Color described with names such as " Red " " Yellow " etc In Colorimetry and Color theory, colorfulness, chroma, and saturation are related but distinct concepts referring to the perceived intensity

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, magenta or yellow). Cyan (saɪæn from Greek κυανός / kyanos, meaning "blue" may be used as the name of any of a number of a range of colors in the blue/green part of Magenta is a purplish red Color evoked by lights with less power in yellowish-green Wavelengths than in blue and red wavelengths ( complements of magenta have 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 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.

To see how different RGB components combine together, here is a selected repertoire of colors and their respective relative intensities for each of the red, green, and blue components:

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. 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 When the exact chromaticities of the red, green, and blue primaries are defined, the color model then becomes an absolute color space, such as sRGB or Adobe RGB; see RGB color spaces for more details. Chromaticity is an objective specification of the Quality of a Color regardless of its luminance that is as determined by its Colorfulness (or saturation 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 sRGB is a standard RGB (Red Green Blue color space created cooperatively by HP and Microsoft for use on monitors printers and the Internet The Adobe RGB color space is an RGB color space developed by Adobe Systems in 1998. An RGB color space is any additive Color space based on the RGB color model.

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

A set of primary colors, such as the sRGB primaries, define a color triangle; only colors within this triangle can be reproduced by mixing the primary colors. sRGB is a standard RGB (Red Green Blue color space created cooperatively by HP and Microsoft for use on monitors printers and the Internet A color triangle is an arrangement of Colors within a Triangle, based on the additive combination of three Primary colors at its corners Colors outside the color triangle are therefore shown here as gray. The primaries and the D65 white point of sRGB are shown. CIE Standard Illuminant D65 (sometimes written D65) is a commonly-used Standard illuminant defined by the International Commission on Illumination A white point (often referred to as reference white or target white in technical documents is a set of tristimulus values or Chromaticity coordinates

The choice of primary colors is related to the physiology of the human eye; 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. Cone cells, or cones, are Photoreceptor cells in the Retina of the Eye which function best in relatively bright Light. Eyes are organs that detect Light, and send signals along the Optic nerve to the visual areas of the brain A color triangle is an arrangement of Colors within a Triangle, based on the additive combination of three Primary colors at its corners ^[3]

The normal three kinds of light-sensitive photoreceptor cells in the 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^[3]). A photoreceptor, or photoreceptor cell, is a specialized type of Neuron (nerve cell found in the Eye 's Retina that is capable of The difference in the signals received from the three kinds allows the brain to differentiate a wide gamut of different colors, while being most sensitive (overall) to yellowish-green light and to differences between hues in the green-to-orange region. In color reproduction including Computer graphics and Photography, the gamut, or color gamut (pronounced /ˈgæmət/ is a certain complete Hue is one of the main properties of a Color described with names such as " Red " " Yellow " etc

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 defined by the chromaticities of the primaries can be reproduced by additive mixing of non-negative amounts of those colors of light. A color triangle is an arrangement of Colors within a Triangle, based on the additive combination of three Primary colors at its corners Chromaticity is an objective specification of the Quality of a Color regardless of its luminance that is as determined by its Colorfulness (or saturation ^[3]

History of RGB color model theory and usage

The first permanent color photograph, taken by J. C. Maxwell in 1861 using three red, green, and violet-blue filters. James Clerk Maxwell (13 June 1831 &ndash 5 November 1879 was a Scottish mathematician and theoretical physicist. Year 1861 ( MDCCCLXI) was a Common year starting on Tuesday (link will display the full calendar of the Gregorian calendar (or a Common

The RGB color model is based on the Young–Helmholtz theory of trichromatic color vision, developed by Thomas Young and Hermann Helmholtz, in the early to mid nineteenth century, and on James Clerk Maxwell's color triangle that elaborated that theory (circa 1860). The Young–Helmholtz theory (proposed in the 19th century by Thomas Young and Hermann von Helmholtz) is a theory of trichromatic Color vision Trichromacy is the condition of possessing three independent channels for conveying Color information derived from the three different cone types Thomas Young refers to Thomas Young (American Revolutionary (1732 – 1777 a member of the Sons of Liberty Thomas Young (scientist (1773 James Clerk Maxwell (13 June 1831 &ndash 5 November 1879 was a Scottish mathematician and theoretical physicist. A color triangle is an arrangement of Colors within a Triangle, based on the additive combination of three Primary colors at its corners Year 1860 ( MDCCLX) was a Leap year starting on Sunday (link will display the full calendar of the Gregorian Calendar (or a Leap year starting

Photography

First experiments with RGB in early color photography were made in 1861 by Maxwell himself, and involved the process of three color-filtered separate takes. "Color film" redirects here For the motion picture equivalent see Color motion picture film. Year 1861 ( MDCCCLXI) was a Common year starting on Tuesday (link will display the full calendar of the Gregorian calendar (or a Common ^[4] 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 color plates and other screen-plate technologies such as the Joly color screen and the Paget process in the early twentieth century. The Autochrome Lumière is an early Color photography process The Joly color screen process is a Color photography technique devised by John Joly in 1895 The Paget process was an early Color photography process patented in Britain in 1912 by G Color photography by taking three separate plates was used by other pioneers, such as Russian Sergey Prokudin-Gorsky in the period 1909 through 1915. Sergey Mikhaylovich Prokudin-Gorsky ( August 31, 1863, Murom  &ndash September 27, 1944, Paris) was a Russian ^[5] Such methods last until about 1960 using the expensive and extremely complex tri-color carbro Autotype process. Year 1960 ( MCMLX) was a Leap year starting on Friday (link will display full calendar of the Gregorian calendar. A carbon print is a photographic print produced by soaking a carbon tissue in a dilute sensitizing solution of Potassium dichromate. 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 ^[6]

When employed, the reproduction of prints from three-plate photos was done by dyes or pigments using the complementary CMY model, by simply using the negative plates of the filtered takes: reverse red gives the cyan plate, and so on.

Television

BBC Test Card F, the first RGB color card aired in the UK in 2nd July 1967. Test Card F is a Test card that was created by the BBC and used on Television in the United Kingdom and in countries elsewhere in the world The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located Events 310 - Pope Miltiades is elected 626 - In fear of assassination Li Shimin ambushes and kills his rival Year 1967 ( MCMLXVII) was a Common year starting on Sunday (link will display full calendar of the 1967 Gregorian calendar.

In pre-electronics, patents on mechanically scanned color systems exist since 1889 in Russia. Year 1889 ( MDCCCLXXXIX) was a Common year starting on Tuesday (link will display the full calendar of the Gregorian calendar (or a Common Russia (Россия Rossiya) or the Russian Federation ( Rossiyskaya Federatsiya) is a transcontinental Country extending The color TV pioneer John Logie Baird demonstrated the world's first RGB color transmission in 1928, and also the world's first color broadcast in 1938, in London. The Television Technology can be divided along two lines those developments that depended upon both mechanical and electronic Principles and John Logie Baird (August 13 1888 – June 14 1946 was a Scottish engineer and inventor of the world's first working television system Year 1928 ( MCMXXVIII) was a Leap year starting on Sunday (link will display full calendar of the Gregorian calendar. Year 1938 ( MCMXXXVIII) was a Common year starting on Saturday (link will display the full calendar of the Gregorian calendar. London ( ˈlʌndən is the capital and largest urban area in the United Kingdom. In his experiments, scanning and displaying were made by mechanical means through spinning colorized wheels. ^[7][8]

The Columbia Broadcasting System (CBS) began experimental RGB field-sequential color system in 1940. CBS Broadcasting Inc ( CBS) is an American radio and Television network. 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 Year 1940 ( MCMXL) was a Leap year starting on Monday (link will display the full 1940 calendar of the Gregorian calendar. Images were electronically scanned, but it still used a moving part: the transparent RGB color wheel rotating at above 1,200 rpm synchronized in front of both the monochromatic camera and the cathode-ray tube (CRT) receiver counterpart. Monochrome comes from the Greek μονόχρωμος ( monochromos) meaning “of one color” which is a combination The cathode ray tube (CRT is a Vacuum tube containing an Electron gun (a source of electrons and a Fluorescent screen with internal or ^[9][10][11]

The modern RGB shadow mask technology for color CRT displays was patented by Werner Flechsig in Germany in 1938. The shadow mask is one of two major technologies used to manufacture Cathode ray tube (CRT Televisions and Computer displays that produce Color Year 1938 ( MCMXXXVIII) was a Common year starting on Saturday (link will display the full calendar of the Gregorian calendar. ^[12]

The National Television System Committee (NTSC) worked in 1950–1953 to develop a color system that was compatible with existing black-and-white sets in the USA, with Radio Corporation of America (RCA) developing the hardware elements. NTSC ( National Television System Committee) is the Analog television system used in the United States, Canada, Japan, Mexico Black-and-white is a number of Monochrome forms in Visual arts. The United States of America —commonly referred to as the RCA Corporation, founded as Radio Corporation of America, was an electronics company in existence from 1919 to 1986 The solution was to encode RGB in the so-called YIQ, a luminance-chrominance color difference signal, in the system that was standardized for use in the United States. YIQ is the Color space used by the NTSC color TV system employed mainly in North and Central America, and Japan. Relative luminance follows the photometric definition of luminance, but with the values normalized to 1 or 100 for a reference white Chrominance ( chroma for short is the signal used in many Video systems to carry the color information of the picture separately from the accompanying luma The difference or distance between two colors is a metric of interest in Color science. In Europe, the French SECAM color TV system was patented in 1956 and the German PAL in 1963. SECAM, also written SÉCAM ( Séquentiel couleur à mémoire, French for "Sequential Color with Memory" is an analog color television system Year 1956 ( MCMLVI) was a Leap year starting on Sunday (link will display full calendar of the Gregorian calendar. PAL, short for Phase Alternating Line, is a colour -encoding system used in Broadcast television systems in large parts of the world Year 1963 ( MCMLXIII) was a Common year starting on Tuesday (link will display full calendar of the Gregorian calendar. They both adapted some NTSC techniques to the European electronics standards, while improving some hue error problems. Because the NTSC color Television standard relies on the absolute phase of the color information color errors occur when the phase of the video signal is altered between The color encoding signals are YUV for PAL systems and YDbDr for SECAM. YDbDr is the Colour space used in the SÉCAM colour Television broadcasting standard which is used in France and some countries of the former

Personal computers

Early personal computers of the late 1970s and early 1980s, such as those from Apple, Atari and Commodore, do not use RGB as their main method to manage colors, but rather composite video. A personal computer ( PC) is any Computer whose original sales price size and capabilities make it useful for individuals and which is intended to be operated Year 1970 ( MCMLXX) was a Common year starting on Thursday (link shows full calendar of the Gregorian calendar. Year 1980 ( MCMLXXX) was a Leap year starting on Tuesday (link displays the 1980 Gregorian calendar) The Atari 8-bit family is a series of 8-bit Home computers manufactured from 1979 to 1992 The VIC-20 ( Germany: VC-20; Japan: VIC-1001) is an 8-bit Home computer which was sold by Commodore Business Machines Composite video is the format of an Analog television (picture only signal before it is combined with a sound signal and modulated onto an RF IBM introduced a 16-color scheme (one bit each for RGB and Intensity) with the Color Graphics Adapter (CGA) for its first IBM PC (1981), later improved with the Enhanced Graphics Adapter (EGA) in 1984. International Business Machines Corporation abbreviated IBM and nicknamed "Big Blue", is a multinational Computer Technology The Color Graphics Adapter ( CGA) originally also called the Color/Graphics Adapter or IBM Color/Graphics Monitor Adapter Year 1981 ( MCMLXXXI) was a Common year starting on Thursday (link displays the 1981 The Enhanced Graphics Adapter (EGA is the IBM PC Computer display standard specification located between CGA and VGA in terms of graphics Year 1984 ( MCMLXXXIV) was a Leap year starting on Sunday (link displays the 1984 Gregorian calendar) The first manufacturer of a truecolor graphic card for PCs (the TARGA) was Truevision in 1987, but was not until the arrival of the Video Graphics Array (VGA) in 1988 that RGB became popular, mainly due to the analog signals in the connection between the adapter and the monitor which allowed a very wide range of RGB colors. See also True Colors (disambiguation. Truecolor is a method of representing and storing graphical image information (especially in computer For the 3D Engine, see Truevision3D. Truevision Inc was a maker of Digital video processing add-on boards for PC computers Year 1987 ( MCMLXXXVII) was a Common year starting on Thursday (link displays 1987 Gregorian calendar) The term Video Graphics Array ( VGA) refers specifically to the display hardware first introduced with the IBM PS/2 line of computers in 1987, but through its widespread Year 1988 ( MCMLXXXVIII) was a Leap year starting on Friday (link displays 1988 Gregorian calendar) An analog or analogue signal is any continuous signal for which the time varying feature (variable of the signal is a representation of some other A visual display unit, often called simply a monitor or display, is a piece of Electrical equipment which displays images generated from the Video

RGB devices

RGB and displays

Cutaway rendering of a color CRT: 1.  Electron guns 2.  Electron beams 3.  Focusing coils 4.  Deflection coils 5.  Anode connection 6.  Mask for separating beams for red, green, and blue part of displayed image 7.  Phosphor layer with red, green, and blue zones 8.  Close-up of the phosphor-coated inner side of the screen

RGB pixels in an LCD TV (on the right: an orange and a blue color; on the left: a close-up of pixels)

Close-up of red, green, and blue LEDs that conform a single pixel in a large scale LED screen.

One common application of the RGB color model is the display of colors on a cathode ray tube (CRT), liquid crystal display (LCD), plasma display, or LED display such as a television, a computer’s monitor, or a large scale screen. The cathode ray tube (CRT is a Vacuum tube containing an Electron gun (a source of electrons and a Fluorescent screen with internal or A plasma display panel (PDP is a type of Flat panel display now commonly used for large TV displays (typically above 37-inch or 940 mm Each pixel on the screen is built by driving three small and very close but still separated RGB light sources. In Digital imaging, a pixel ( pict ure el ement is the smallest piece of information in an image 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 each pixel can be represented in the computer memory or interface hardware (for example, a graphics card) as binary values for the red, green, and blue color components. Digital image processing is the use of computer Algorithms to perform Image processing on Digital images As a subfield of Digital signal processing A video card, also known as a graphics accelerator card, display adapter, or graphics card, is a hardware component whose function is to When properly managed, these values are converted into intensities or voltages via gamma correction to correct the inherent nonlinearity of some devices, such that the intended intensities are reproduced on the display. Gamma correction, gamma nonlinearity, gamma encoding, or often simply gamma, is the name of a nonlinear operation used to code and decode luminance

Video electronics

RGB is also the term referring to a type of component video signal used in the video electronics industry. This article is about analog component video for the processing of color components in digital video see Digital video, Chroma subsampling and YCbCr Video is the technology of electronically capturing, Recording, processing storing transmitting and reconstructing a sequence of Still images 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 since it is the best quality signal that can be carried on the standard SCART connector. SCART (from Syndicat des Constructeurs d'Appareils Radiorécepteurs et Téléviseurs) Outside Europe, RGB is not very popular as a video signal format; S-Video takes that spot in most non-European regions. Super Video or Separated Video abbreviated S-Video and also known as Y/C is an analog video signal that carries the video data as two separate However, almost all computer monitors around the world use RGB.

Video framebuffer

A framebuffer is a digital device for computers which stores in the so-called video memory (conformed by an array of Video RAM or similar chips) the digital image to be displayed on the monitor. A framebuffer is a video output device that drives a video display from a memory buffer containing a complete frame of data Driven by software, the CPU or other specialized chips write the appropriate bytes in the video memory to conform the image, which an electronic video generator sends to the monitor. A byte (pronounced "bite" baɪt is the basic unit of measurement of information storage in Computer science. Modern systems encode pixel color values by devoting some bits groupings for each of the RGB separate components. A bit is a binary digit, taking a value of either 0 or 1 Binary digits are a basic unit of Information storage and communication RGB information can be either carried by the pixel bits themselves or in a separate Color Look-Up Table (CLUT) if indexed color graphic modes are used. A colour look-up table (CLUT is a device which converts the logical colour numbers stored in each Pixel of Video memory into physical colours normally represented In computing indexed color is a technique to manage Digital images colors in a limited fashion in order to save computer's memory and file storage

By using an appropriate combination of red, green, and blue intensities, many colors can be displayed. Current typical display adapters use up to 24-bits of information for each pixel: 8-bit per component multiplied by three components (see the Digital representations section below). A video card, also known as a graphics accelerator card, display adapter, or graphics card, is a hardware component whose function is to The IBM System/360, announced in 1964, was an extremely popular computer system with 24-bit addressing and 32-bit general registers and arithmetic With this system, 16,777,216 (256³ or 2²⁴) discrete combinations of R, G and B values are allowed, providing thousands of different (though not necessarily distinguishable) hue, saturation, and lightness shades. Hue is one of the main properties of a Color described with names such as " Red " " Yellow " etc In Colorimetry and Color theory, colorfulness, chroma, and saturation are related but distinct concepts referring to the perceived intensity 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

Nonlinearity

Main article: Gamma correction

In classic cathode ray tube (CRT) devices, the brightness of a given point over the phosphorescent screen due to the impact of accelerated electrons is not proportional to the voltage applied to electrons in their RGB electron guns, but to an expansive function of that voltage. Gamma correction, gamma nonlinearity, gamma encoding, or often simply gamma, is the name of a nonlinear operation used to code and decode luminance The cathode ray tube (CRT is a Vacuum tube containing an Electron gun (a source of electrons and a Fluorescent screen with internal or Phosphorescence is a specific type of Photoluminescence related to fluorescence. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J An electron gun (also called electron emitter) is an electrical component that produces an Electron beam that has a precise Kinetic energy and is most often The amount of this deviation is known as its gamma value (γ), the argument for a power law function, which closely describes this behaviour. Gamma correction, gamma nonlinearity, gamma encoding, or often simply gamma, is the name of a nonlinear operation used to code and decode luminance A power law is any Polynomial relationship that exhibits the property of Scale invariance. 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 thru Digital-to-Analog Converters—DAC). In Electronics, a digital-to-analog converter ( DAC or D-to-A) is a device for converting a digital (usually binary code to an Analog signal 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 that when displaying the full (1. 0, 1. 0, 1. 0), instead of at 50%. ^[13] To obtain the correct response, a gamma correction is used in encoding the image data, and possibly further corrections as part of the color calibration process of the device. Gamma correction, gamma nonlinearity, gamma encoding, or often simply gamma, is the name of a nonlinear operation used to code and decode luminance The aim of color calibration is to measure or adjust the color response of a device (input or output to establish a known relationship to a standard Color space. Gamma affects black-and-white TV as well as color. Black-and-white is a number of Monochrome forms in Visual arts. In standard color TV, signals are already broadcast in a gamma-compensated fashion by TV stations.

Display technologies different from CRT (as LCD, plasma, LED, etc. ) may behave nonlinearly in different ways. When they are intended to display standard TV and video shows, they are built in a such way that they behave in gamma like an older 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 have also 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

The Bayer arrangement of color filters on the pixel array of an digital image sensor

In color television and video cameras manufactured before the 1990's, the incoming light was separated by prisms and filters into the three RGB primary colors feeding each color into a separate video camera tube (or pickup tube). A professional Video camera (often called a television camera even though the use has spread is a high-end device for recording electronic moving images (as opposed Year 1990 ( MCMXC) was a Common year starting on Monday (link displays the 1990 Gregorian calendar) In Optics, a prism is a transparent optical element with flat polished surfaces that refract Light. 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 (CCD These tubes are a type of cathode ray tube, not to be confused with that of CTR displays.

With the arriving of commercially viable charge-coupled device (CCD) technology in the 1980's, first the pickup tubes were replaced with this kind of sensors. A charge-coupled device ( CCD) is an analog Shift register, that enables the transportation of analog signals (electric charges through successive stages (capacitors Year 1980 ( MCMLXXX) was a Leap year starting on Tuesday (link displays the 1980 Gregorian calendar) Later, higher scale integration electronics was applied (mainly by Sony), simplifying and even removing the intermediate opticals, up to a point to reduce the size of video cameras for domestic use until convert them in handy and full camcorders. is a multinational conglomerate corporation headquartered in Minato Tokyo, Japan, and one of the world's largest Media conglomerates with A video camera is a Camera used for electronic Motion picture acquisition initially developed by the Television industry but now common in other applications A camcorder is a portable Consumer electronics device for recording Video and audio using a built-in recorder unit Current webcams and mobile phones with cameras are the most miniaturized commercial forms of such technology. Webcams ( web cameras) are small cameras (usually though not always Video cameras, whose images can be accessed using the World Wide Web, instant

Photographic digital cameras that use a CMOS or CCD image sensor often operate with some variation of the RGB model. Many compact digital still cameras can record Sound and moving Video as well as still Photograph. Complementary metal–oxide–semiconductor ( CMOS) (pronounced "see-moss" siːmɔːs ˈsiːmɒs is a major class of Integrated circuits CMOS technology An image sensor is a device that converts an optical image to an electric signal In a Bayer filter arrangement, green is given the double more detectors than red and blue (ratio 1:2:1) in order to achieve higher luminance resolution than chrominance resolution. Explanation Bryce Bayer's patent called the green photosensors luminance-sensitive elements and the red and blue ones chrominance-sensitive elements. Luminance is a photometric measure of the density of Luminous intensity in a given direction Chrominance ( chroma for short is the signal used in many Video systems to carry the color information of the picture separately from the accompanying luma The sensor have 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 in the demosaicing process to build-up the complete image. In the mathematical subfield of Numerical analysis, interpolation is a method of constructing new data points within the range of a Discrete set of A demosaicing Algorithm is a digital image process used to interpolate a complete image from the partial raw data received from the color-filtered Also, other processes used to be applied in order to map the camera RGB measurements into a standard RGB color space as sRGB. An RGB color space is any additive Color space based on the RGB color model. sRGB is a standard RGB (Red Green Blue color space created cooperatively by HP and Microsoft for use on monitors printers and the Internet

RGB and scanners

In computing, an 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. Historical precedent Scanners can be considered the successors of early telephotography input devices consisting of a rotating drum with a single Photodetector at 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 lines as analog amplitude modulation signals through standard telephonic lines to appropriate receivers; such systems were in use in press since the 1920s to the mid 1990s. A scan line is one line or row in a Raster scanning pattern such as a video line on a Cathode ray tube (CRT display of a television or computer An analog or analogue signal is any continuous signal for which the time varying feature (variable of the signal is a representation of some other Amplitude modulation ( AM) is a technique used in electronic communication most commonly for transmitting information via a Radio Carrier wave Color telephotographs were sent as three separated RGB filtered images consecutively.

Currently available scanners typically use charge-coupled device (CCD) or contact image sensor (CIS) as the image sensor, whereas older drum scanners use a photomultiplier tube as the image sensor. A charge-coupled device ( CCD) is an analog Shift register, that enables the transportation of analog signals (electric charges through successive stages (capacitors 'Contact Image Sensors (CIS' are a relatively recent technological innovation in the field of optical flatbed scanners that are rapidly replacing CCDs in low power and portable Photomultiplier tubes ( photomultipliers or PMT s for short members of the class of Vacuum tubes and more specifically Phototubes are extremely Early color film scanners used a halogen lamp and a three-color filter wheel, so three exposures were needed to scan a single color image. A halogen lamp is an Incandescent lamp in which a Tungsten filament is sealed into a compact transparent envelope filled with an inert gas plus a small amount of 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 LEDs.

Numeric representations

A typical RGB color selector in graphic software. Every slider ranges from 0 to 255. A slider is a graphical widget in a GUI with which a user may set a value by moving an indicator usually in a horizontal fashion

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. In Computing, floating point describes a system for numerical representation in which a string of digits (or Bits represents a Real number.
• Each color component value can also be written as a percentage, from 0% to 100%. In Mathematics, a percentage is a way of expressing a number as a Fraction of 100 ( per cent meaning "per hundred"
• In computing, the component values are often stored as integer numbers in the range 0 to 255, the range that a single 8-bit byte can offer (by encoding 256 distinct values). The integers (from the Latin integer, literally "untouched" hence "whole" the word entire comes from the same origin but via French A byte (pronounced "bite" baɪt is the basic unit of measurement of information storage in Computer science.
• High-end digital image equipment can deal with the integer range 0 to 65,535 for each primary color, by employing 16-bit words instead of 8-bit bytes. In Computing, " word " is a term for the natural unit of data used by a particular computer design

For example, the full intensity red [_] is written in the different RGB notations as:

Notation	RGB triplet
Arithmetic	(1. 0, 0. 0, 0. 0)
Percentage	(100%, 0%, 0%)
Digital 8-bit per channel	(255, 0, 0)
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 cameras and TV broadcasting and receiving due to gamma correction, for example. Many compact digital still cameras can record Sound and moving Video as well as still Photograph. Gamma correction, gamma nonlinearity, gamma encoding, or often simply gamma, is the name of a nonlinear operation used to code and decode luminance ^[14] Linear and nonlinear transformations are often dealt with via digital image processing. Digital image processing is the use of computer Algorithms to perform Image processing on Digital images As a subfield of Digital signal processing Representations with only 8 bits per component are considered sufficient if gamma encoding is used,^[15] but sometimes even 8-bit linear is used. ^[16]

Geometric representation

The RGB color model mapped to a cube. The horizontal x-axis as red values increasing to the left, y-axis as blue increasing to the lower right and the vertical z-axis as green increasing towards the top. The origin, black, is hidden behind the cube.

See also RGB color space

Since colors are usually defined by three components, not only in the RGB model, but also in other color models such as CIELAB and Y'UV, among others, then a three-dimensional volume is described by treating the component values as ordinary cartesian coordinates in a euclidean space. An RGB color space is any additive Color space based on the RGB color model. A Lab color space is a color-opponent space with dimension L for lightness and a and b Three-dimensional space is a geometric model of the physical Universe in which we live The volume of any solid plasma vacuum or theoretical object is how much three- Dimensional space it occupies often quantified numerically In Mathematics, the Cartesian coordinate system (also called rectangular coordinate system) is used to determine each point uniquely in a plane For the RGB model, this is represented by a cube using non-negative values within a 0–1 range and assigning black to the origin at the vertex (0, 0, 0), and with increasing intensity values running along the three axis 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 of two given RGB colors by simply calculating the distance between them: the shorter the distance, the higher the similarity. The difference or distance between two colors is a metric of interest in Color science. In Mathematics, the Euclidean distance or Euclidean metric is the "ordinary" Distance between two points that one would measure with a ruler Out-of-gamut computations can be performed this way, too. In color reproduction including Computer graphics and Photography, the gamut, or color gamut (pronounced /ˈgæmət/ is a certain complete

Digital representations

The RGB color model is the most common way to encode color in computing, and several different binary digital representations are in use. Color depth. or bit depth, is a Computer graphics term describing the number of Bits used to represent the Color of a single Pixel A binary image is a Digital image that has only two possible values for each Pixel. In Computing, a grayscale or greyscale Digital image is an image in which the value of each Pixel 8-bit color graphics is a method of storing image information in a computer's memory or in an image file such that each Pixel is represented by one 8-bit Byte. Highcolor graphics (variously spelled Hicolor, Hicolour, and Highcolour, and known as Thousands of colors on a Macintosh) is a method See also True Colors (disambiguation. Truecolor is a method of representing and storing graphical image information (especially in computer Deep Color is a term used to describe a method of representing graphical image data using an extremely large number of shades hues and luminosities capable of displaying billions of possible In computing indexed color is a technique to manage Digital images colors in a limited fashion in order to save computer's memory and file storage In Computer graphics, a palette is either a given finite set of Colors for the management of Digital images (that is a color palette) or Web colors are Colors used in designing web pages and the methods for describing and specifying those colors A digital system uses discrete (discontinuous values usually but not always Symbolized Numerically (hence called "digital" to represent information for The main characteristic of all of them is the quantization of the possible values per component (technically a sample) by using only integer numbers within some range, usually form 0 to a some power of two minus one (2ⁿ – 1) to fit them into some bit groupings. In Digital signal processing, quantization is the process of approximating a continuous range of values (or a very large set of possible discrete values by a relatively-small In Signal processing, sampling is the reduction of a Continuous signal to a Discrete signal. The integers (from the Latin integer, literally "untouched" hence "whole" the word entire comes from the same origin but via French A bit is a binary digit, taking a value of either 0 or 1 Binary digits are a basic unit of Information storage and communication

As usual in computing, the values can be represented either in decimal and in hexadecimal notation as well, as is the case of HTML colors text-encoding convention. In Mathematics and Computer science, hexadecimal (also base -, hexa, or hex) is a Numeral system with a Web colors are Colors used in designing web pages and the methods for describing and specifying those colors

The 24-bit RGB representation

RGB values encoded in 24 bits per pixel (bpp) are specified using three 8-bit unsigned integers (0 through 255) representing the intensities of red, green, and blue. For a full listing of computer's color palettes see List of palettes This list of monochrome and RGB palettes includes This representation is the current mainstream standard representation for the so-called truecolor and common color interchange in image file formats such as JPEG or TIFF. See also True Colors (disambiguation. Truecolor is a method of representing and storing graphical image information (especially in computer Image file formats are standardized means of organising and storing images It allows more than 16 million different combinations (hence the term millions of colors some systems for this mode), many of them indistinguishable to the human eye.

The following image shows the three "fully saturated" faces of a 24-bpp RGB cube, unfolded into a plane:

(0, 0, 0) is black (255, 255, 255) is white (255, 0, 0) is red (0, 255, 0) is green (0, 0, 255) is blue (255, 255, 0) is yellow (0, 255, 255) is cyan (255, 0, 255) is magenta	yellow (255,255,0)	green (0,255,0)	cyan (0,255,255)
	red (255,0,0)		blue (0,0,255)
		red (255,0,0)	magenta (255,0,255)

The above definition uses a convention known as full-range RGB. Black is the Color of objects that do not emit or Reflect Light in any part of the Visible spectrum; they absorb all such frequencies of White is a Color, the perception which is evoked by Light that stimulates all three types of color sensitive Cone cells in the Human eye 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 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- nm. Blue is a Colour, the Perception of which is evoked by 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 Cyan (saɪæn from Greek κυανός / kyanos, meaning "blue" may be used as the name of any of a number of a range of colors in the blue/green part of Magenta is a purplish red Color evoked by lights with less power in yellowish-green Wavelengths than in blue and red wavelengths ( complements of magenta have Color values are also often scaled from and to the range 0. 0 through 1. 0, specially they are mapped from/to other color models and/or encodings.

The 256 levels of a primary usually do not represent equally spaced intensities, due to 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

This representation cannot offer the exact mid point 127. 5, nor other non-integer values, as bytes do not hold fractional values, so these need to be rounded or truncated to a nearby integer value. A byte (pronounced "bite" baɪt is the basic unit of measurement of information storage in Computer science. ^[17] For example, Microsoft considers the color "medium gray"^[18] to be the (128,128,128) RGB triplet in its default palette. Microsoft Corporation is an American multinational Computer technology Corporation, which rose to dominate the Home computer For a full listing of computer's color palettes see List of palettes Computer systems that use an 4-bit or 8-bit Pixel The effect of such quantization (for every value, not only the midpoint) is usually not noticeable, but may build up in repeated editing operations or colorspace conversions. ^[19]

Typically, RGB for digital video is not full range. Digital video is a type of Video recording system that works by using a Digital rather than an analog video signal Instead, video RGB uses a convention with scaling and offsets such that (16, 16, 16) is black, (235, 235, 235) is white, etc. Black is the Color of objects that do not emit or Reflect Light in any part of the Visible spectrum; they absorb all such frequencies of White is a Color, the perception which is evoked by Light that stimulates all three types of color sensitive Cone cells in the Human eye For example, these scalings and offsets are used for the digital RGB definition in the CCIR 601 standard. ITU-R Recommendation BT601, more commonly know by the abbreviations Rec

Beyond the 24-bit RGB

32-bit graphic mode

The so-called 32 bpp display graphic mode is identical in precision to the 24 bpp mode; there are still only eight bits per component, and the eight extra bits are often not used at all. The reason for the existence of the 32 bpp mode is the higher speed at which most modern 32-bit (and better) hardware can access data that is aligned to byte addresses evenly divisible by a power of two, compared to data not so aligned. The range of Integer values that can be stored in 32 bits is 0 through 4294967295 or −2147483648 through 2147483647 using Two's complement encoding Data structure alignment is the way data is arranged and accessed in computer memory A byte (pronounced "bite" baɪt is the basic unit of measurement of information storage in Computer science.

32-bit graphic mode with simple video overlay

Some graphics hardware allows the unused byte into the 32-bit mode to be used as an 8-bit paletted overlay. In Computer graphics, a palette is either a given finite set of Colors for the management of Digital images (that is a color palette) or Video overlay is any technique used to display a Video window on a computer display while bypassing the chain of CPU -> Graphics card -> Computer monitor A certain palette entry (often 0 or 255) is designated as being transparent, i. e. , where the overlay is this value the truecolor image is shown. Otherwise the overlay value is looked up in the palette and used. This allows for GUI elements (such as menus or the mouse cursor) or information to be overlayed over a truecolor image without modifying it. When the overlay needs to be removed, it is simply cleared to the transparent value and the truecolor image is displayed again. This feature was often found on graphics hardware for Unix workstations in the 90s and later on some PC graphics cards (most notably those by Matrox). Unix (officially trademarked as UNIX, sometimes also written as Unix with Small caps) is a computer Matrox Electronic Systems Ltd is a Canadian company based in Dorval Quebec, which produces video card components and equipment for Personal computers However, PC graphics cards (and the systems they are used in) now have plentiful memory to use as a backing store and this feature has mostly disappeared.

32-bit RGBA (RGB plus alpha channel)

With the need for compositing images came a variant of 24-bit RGB which includes an extra 8-bit channel for transparency, thus resulting also in a 32-bit format. The transparency channel is commonly known as the alpha channel, so the format is named RGBA. In Computer graphics, alpha compositing is the process of combining an image with a background to create the appearance of partial transparency RGBA stands for R ed G reen B lue A lpha While it is sometimes described as a color space it is actually simply a use of the RGB color model with Note again that since it does not change anything in the RGB model, RGBA is not a distinct color model, it is only a representation that integrates transparency information along with the color information. This extra channel allows for alpha blending of the image over another, and is a feature of the PNG format. In Computer graphics, alpha compositing is the process of combining an image with a background to create the appearance of partial transparency Portable Network Graphics ( PNG) is a bitmapped image format that employs Lossless data compression.

48-bit RGB

High precision color management typically uses up to 16 bits per component, resulting in 48 bpp. This makes it possible to represent 65,536 tones of each color component instead of 256. This is primarily used in professional image editing, like Adobe Photoshop for maintaining greater precision when a sequence of more than one image filtering algorithms is used on the image. With only 8 bit per component, rounding errors tend to accumulate with each filtering algorithm that is employed, distorting the end result. For the acrobatic movement roundoff see Roundoff. A round-off error, also called rounding error, is the difference between the Sometimes also called 16-bit mode due to the precision by component, not to be confused with 16-bit Highcolor which is a more limited representation (see below). Highcolor graphics (variously spelled Hicolor, Hicolour, and Highcolour, and known as Thousands of colors on a Macintosh) is a method

Limited representations below 24-bit RGB

16-bit RGB (Highcolor)

A 16-bit mode known as Highcolor, in which there are either 5 bits per color, called 555 mode (32,768 total colors), or the same with an extra bit for green (because the green component contributes most to the brightness of a color in the human eye), called 565 mode (65,535 colors). Highcolor graphics (variously spelled Hicolor, Hicolour, and Highcolour, and known as Thousands of colors on a Macintosh) is a method For a full listing of computer's color palettes see List of palettes This list of monochrome and RGB palettes includes For a full listing of computer's color palettes see List of palettes This list of monochrome and RGB palettes includes (In general, a good RGB representation needs 1 bit more for red than blue and 1 more bit for green,^[20] but this can not be fully achieved within a 16-bit word. In Computing, " word " is a term for the natural unit of data used by a particular computer design ) This was the high-end for some display adapters for personal computers during the 1990's, but today is considered slightly obsolete in favour of the 24 or 32 bpp graphic modes. A video card, also known as a graphics accelerator card, display adapter, or graphics card, is a hardware component whose function is to A personal computer ( PC) is any Computer whose original sales price size and capabilities make it useful for individuals and which is intended to be operated Year 1990 ( MCMXC) was a Common year starting on Monday (link displays the 1990 Gregorian calendar) It is still in use in many devices with color screens as cell phones, digital cameras, personal digital assistants (PDA) and portable videogame consoles. Many compact digital still cameras can record Sound and moving Video as well as still Photograph.

RGB arrangements for 8-bit indexed color

Mosaic of image thumbnails rendered with a single shared master palette of 6×8×5 RGB levels plus 16 additional grays.

Display adapters and image file formats using indexed-color techniques limit the simultaneously available colors per image up to 256, 8 bits per pixel. A video card, also known as a graphics accelerator card, display adapter, or graphics card, is a hardware component whose function is to This is a comparison of Image file formats. General Ownership of the format and related information In computing indexed color is a technique to manage Digital images colors in a limited fashion in order to save computer's memory and file storage The selected colors are arranged into a palette, and the actual image pixels values do not represent RGB triplets, but mere indices into the palette, which in turn stores the 24-bit RGB triplets for every color in the image, so colors are addressed indirectly. In Computer graphics, a palette is either a given finite set of Colors for the management of Digital images (that is a color palette) or In Digital imaging, a pixel ( pict ure el ement is the smallest piece of information in an image

Every image can have its own color selection (or adaptive palette) when indexed color is employed. For a full listing of computer's color palettes see List of palettes Computer systems that use an 4-bit or 8-bit Pixel But this scheme has the inconvenience that two or more indexed-color images with incompatible palettes cannot be properly displayed simultaneously where the 256-color limitation is imposed by the system's hardware.

One solution is to use an intermediate master palette which comprises a full RGB selection with limited levels to the red, green, and blue components, in order to fit it at all within 256 color entries. In Computer graphics, a palette is either a given finite set of Colors for the management of Digital images (that is a color palette) or

Usual limited RGB repertoires include 6×6×6 levels with 216 combinations (the Web colors case), 6×7×6 levels with 252 combinations, 6×8×5 levels with 240 combinations and 8×8×4 levels with the full 256 combinations (see RGB arrangements for samples). Web colors are Colors used in designing web pages and the methods for describing and specifying those colors For a full listing of computer's color palettes see List of palettes Computer systems that use an 4-bit or 8-bit Pixel

3-bit RGB

The minimum RGB binary representation is 3-bit RGB, one bit per component. For a full listing of computer's color palettes see List of palettes This list of monochrome and RGB palettes includes Typical for early color terminals in the 1970's, it is still used today with the Teletext TV retrieval service. A computer terminal is an electronic or electromechanical hardware device that is used for entering data into and displaying data from a Computer or a Computing Year 1970 ( MCMLXX) was a Common year starting on Thursday (link shows full calendar of the Gregorian calendar. Teletext (or "broadcast Teletext" is a Television information retrieval service developed in the United Kingdom in the early

Colors in web-page design

Main article: Web colors

Colors used in web-page design are commonly specified using RGB; see web colors for an explanation of how colors are used in HTML and related languages. Web colors are Colors used in designing web pages and the methods for describing and specifying those colors Web colors are Colors used in designing web pages and the methods for describing and specifying those colors HTML, an initialism of HyperText Markup Language, is the predominant Markup language for Web pages It provides a means to describe the structure Initially, the limited 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 combinations of red, green, and blue where each color can take one of six values (in hexadecimal): #00, #33, #66, #99, #CC or #FF (based on the 0 to 255 range for each value discussed above). Web colors are Colors used in designing web pages and the methods for describing and specifying those colors In Mathematics and Computer science, hexadecimal (also base -, hexa, or hex) is a Numeral system with a Clearly, 6 cubed = 216. 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, the perceived intensity on a standard 2. Gamma correction, gamma nonlinearity, gamma encoding, or often simply gamma, is the name of a nonlinear operation used to code and decode luminance 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. Web colors are Colors used in designing web pages and the methods for describing and specifying those colors

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

Main article: 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. In digital imaging systems color management is the controlled conversion between the Color representations of various devices such as Image scanners Digital Color management results in several transparent conversions between device-independent and device-dependent color spaces (RGB and others, as CMYK for color printing) during a typical production cycle, in order to ensure color consistency throughout the process. 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 CMYK (short for '''c'''yan, '''m'''agenta, '''y'''ellow, and k ey ( Black) and often referred to as process color Along with the creative processing, such interventions on digital images can damage the color accuracy and image detail, especially where the gamut is reduced. In color reproduction including Computer graphics and Photography, the gamut, or color gamut (pronounced /ˈgæmət/ is a certain complete 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, use either the Lab color space or the CIE 1931 color space as a Profile Connection Space when translating between color spaces. A Lab color space is a color-opponent space with dimension L for lightness and a and b In the study of the perception of Color, one of the first mathematically defined Color spaces was the CIE 1931 XYZ color space (also known as CIE 1931 color space In digital imaging systems color management is the controlled conversion between the Color representations of various devices such as Image scanners Digital ^[21]

RGB model and luminance–chrominance formats relationship

All luminance–chrominance formats used in the different TV and video standards such as YIQ for NTSC, YUV for PAL, YD_BD_R for SECAM, and YP_BP_R for composite 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. Relative luminance follows the photometric definition of luminance, but with the values normalized to 1 or 100 for a reference white Chrominance ( chroma for short is the signal used in many Video systems to carry the color information of the picture separately from the accompanying luma YIQ is the Color space used by the NTSC color TV system employed mainly in North and Central America, and Japan. NTSC ( National Television System Committee) is the Analog television system used in the United States, Canada, Japan, Mexico PAL, short for Phase Alternating Line, is a colour -encoding system used in Broadcast television systems in large parts of the world YDbDr is the Colour space used in the SÉCAM colour Television broadcasting standard which is used in France and some countries of the former SECAM, also written SÉCAM ( Séquentiel couleur à mémoire, French for "Sequential Color with Memory" is an analog color television system YPBPR is a Color space used in Video electronics in particular in reference to Component video cables Composite video is the format of an Analog television (picture only signal before it is combined with a sound signal and modulated onto an RF 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 schemes such as JPEG and MPEG store RGB color internally in YC_BC_R format, a digital luminance-chrominance format based on YP_BP_R. The Moving Picture Experts Group, commonly referred to as simply MPEG, is a Working group of ISO / IEC charged with the development of video and YCbCr or Y'CbCr is a family of Color spaces used as a part of the Color image pipeline in Video and Digital photography systems The use of YC_BC_R also allows to perform lossy subsampling with the chroma channels (typically to 4:2:2 or 4:1:1 ratios), which it aids to reduce the resultant file size. A lossy compression method is one where compressing data and then decompressing it retrieves data that may well be different from the original but is close enough to be useful Chroma subsampling is the practice of encoding images by implementing less resolution for chroma Information than for luma information

See also

• Color banding
• SCART connector
• Color theory
• List of palettes

References

External links

• Demonstrative color conversion applet