Adobe RGB color space
Encyclopedia
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...
developed by Adobe Systems
Adobe Systems
Adobe Systems Incorporated is an American computer software company founded in 1982 and headquartered in San Jose, California, United States...
in 1998. It was designed to encompass most of the colors achievable on CMYK color printers
Printing
Printing is a process for reproducing text and image, typically with ink on paper using a printing press. It is often carried out as a large-scale industrial process, and is an essential part of publishing and transaction printing....
, but by using RGB
RGB color model
The RGB color model is an additive color model in which red, green, and blue light is added together in various ways to reproduce a broad array of colors...
primary colors on a device such as the computer display
Computer display
A monitor or display is an electronic visual display for computers. The monitor comprises the display device, circuitry, and an enclosure...
. The Adobe RGB 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...
encompasses roughly 50% of the visible colors specified by 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....
, improving upon the 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 the sRGB color space
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...
primarily in cyan-greens.
Specification
In Adobe RGB, colors are specified as
triplets, where each of the R, G, and B components can have values between 0 and 1. When displayed on a monitor, the exact chromaticitiesChromaticity
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 white point
, the black point 
, and the primaries [
etc.] are specified. Moreover, the luminanceLuminance
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...
of the monitor should be 160 cd
Candela
The candela is the SI base unit of luminous intensity; that is, power emitted by a light source in a particular direction, weighted by the luminosity function . A common candle emits light with a luminous intensity of roughly one candela...
/m2 at the white point, and 0.5557 cd/m2 at the black point, which implies a contrast ratio of 287.9. The environment of the monitor is illuminated at 32 lx
Lux
The lux is the SI unit of illuminance and luminous emittance, measuring luminous flux per unit area. It is used in photometry as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface...
.
As with sRGB, the RGB component values in Adobe RGB are not proportional to the luminances. Rather, a gamma
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...
of 2.2 is assumed, without the linear segment near zero that is present in sRGB. The precise gamma value is
, or 2.19921875.The white point corresponds to D65. The chromaticities of the primary colors and the white point are as follows:
| color | x | y |
|---|---|---|
| Red | 0.6400 | 0.3300 |
| Green | 0.2100 | 0.7100 |
| Blue | 0.1500 | 0.0600 |
| White | 0.3127 | 0.3290 |