CIE 1931 xy chromaticity diagram showing the gamut of the sRGB color space and location of the primaries. The D65 white point is shown in the center. Note that areas outside the triangle cannot be accurately colored, because they are out of the gamut of computer displays.

Plot of the sRGB intensities versus sRGB numerical values (red), and this function's slope in log-log space (blue) which is the effective gamma at each point. Below a compressed value of 0.04045 or a linear intensity of 0.00313, the curve is linear so the gamma is 1. Behind the red curve is a dashed black curve showing an exact gamma = 2.2 power law.

sRGB color space is a standard RGB (Red Green Blue) color space created cooperatively by HP and Microsoft for use on monitors, printers, and the Internet. It was originally proposed in 1995 by Ralf Kuron of FOGRA^{[citation needed]} as a pragmatic approach in connection to ICC. It has been endorsed by the W3C, Exif, Intel, Pantone, Corel, and many other industry players, is also well accepted by open-source software such as the GIMP, and is used in proprietary and open graphics file formats such as SVG. Image File history File links Download high resolution version (1140x1260, 363 KB) CIE 1931 xy chromaticity diagram showing the sRGB gamut and the D65 white point Please see http://commons. ... Image File history File links Download high resolution version (1140x1260, 363 KB) CIE 1931 xy chromaticity diagram showing the sRGB gamut and the D65 white point Please see http://commons. ... The International Commission on Illumination (usually known as the CIE for its French-language name Commission Internationale de lEclairage) is the international authority on light, illumination, colour, and colour spaces. ... In color reproduction, including computer graphics and photography, the gamut, or color gamut (pronounced ), is a certain complete subset of colors. ... A white point is one of a number of reference illuminants used in colorimetry which serve to define the color white. Depending on the application, different definitions of white are needed to give acceptable results. ... In color reproduction, including computer graphics and photography, the gamut, or color gamut (pronounced ), is a certain complete subset of colors. ... Image File history File links SRGB_gamma. ... Image File history File links SRGB_gamma. ... An RGB color space is any additive color space based on the RGB color model. ... The Hewlett-Packard Company (NYSE: HPQ), commonly known as HP, is a very large, global company headquartered in Palo Alto, California, United States. ... Microsoft Corporation (NASDAQ: MSFT), (founded 1975), headquartered in Redmond, Washington, USA, is the worlds largest software company (with over 50,000 employees in various countries, as of May 2004). ... The International Color Consortium was formed in 1993 by eight industry vendors in order to create a universal color management system that would function transparently across all operating systems and software packages. ... The World Wide Web Consortium (W3C) is a consortium that produces standards—recommendations, as they call them—for the World Wide Web. ... Exchangeable image file format (Exif) is a specification for the image file format used by digital cameras. ... Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ... For the record label, see Pantone Music. ... Corel Corporation is a computer software company headquartered in Ottawa, Ontario, Canada. ... Open source software is computer software whose source code is available under a license (or arrangement such as the public domain) that permits users to study, change, and improve the software, and to redistribute it in modified or unmodified form. ... The GNU Image Manipulation Program, or GIMP, is a raster graphics editor application with some support for vector graphics. ... It has been suggested that this article or section be merged into Comparison of graphics file formats. ... Scalable Vector Graphics (SVG) is a XML markup language for describing two-dimensional vector graphics, both static and animated, and either declarative or scripted. ...

The sRGB color space is well-specified, and is designed to match typical home and office viewing conditions, rather than the darker environment typically used for commercial color matching. It uses the ITU-R BT.709-2 reference primaries, (the same as are used in an SMPTE broadcast monitor^{[citation needed]}) and a transfer function (gamma curve) typical of CRTs. This specification allows sRGB to be directly displayed by non-ICC-aware applications on typical monitors, a factor which greatly aided its acceptance. Nearly all software was and is designed with the assumption that an 8-bit/channel image file placed unchanged onto an 8-bit/channel display will appear much as the sRGB specification dictates. LCD displays, digital cameras, printers, and scanners all follow the sRGB standard. Devices which do not naturally follow sRGB (as older CRT monitors did) include compensating circuitry or software so that in the end they also obey this standard (this is somewhat less true for high-end professional equipment, which still generally defaults to sRGB). For this reason, one can assume (in the absence of embedded profiles or any other information) that any 8-bit/channel image file, and any 8-bit/channel image API or device interface, is in the sRGB color space. Example of CRT gamma correction Plot of the sRGB standard gamma-expansion nonlinearity (red), and its local gamma value, slope in log–log space (blue). ... LCD redirects here. ... 10 MP Nikon D200 and a Nikon film scanner The Canon EOS 350D The Canon PowerShot A95 Digital photography, as opposed to film photography, uses electronic devices to record and capture the image as binary data. ...

The sRGB gamma can not be expressed as a single numerical value. The overall gamma is approximately 2.2, consisting of a linear (gamma 1.0) section near black, and a non-linear section elsewhere involving a 2.4 exponent and a gamma (slope of log output versus log input) changing from 1.0 through about 2.3. Example of CRT gamma correction Plot of the sRGB standard gamma-expansion nonlinearity (red), and its local gamma value, slope in log–log space (blue). ...

Overview

sRGB defines the chromaticities of the red, green, and blue primaries, the colors where one of the three channels is at the maximum value and the other two are at zero. In CIE xy chromaticity coordinates red is at [0.6400, 0.3300], green is at [0.3000, 0.6000], and blue is at [0.1500, 0.0600], and the white point is the D65 white point at [0.3127,0.3290]. As with any RGB color space, for non-negative values of R, G, and B it is not possible to represent colors outside the color triangle defined by the primaries, the chromaticity gamut, which is well inside the range of colors visible to a human. A primary color is a color that cannot be created by mixing other colors in the gamut of a given color space. ... In the study of the perception of color, one of the first mathematically defined color spaces was the CIE XYZ color space (also known as CIE 1931 color space), created by the International Commission on Illumination (CIE) in 1931. ... A white point is one of a number of reference illuminants used in colorimetry which serve to define the color white. Depending on the application, different definitions of white are needed to give acceptable results. ... An RGB color space is any additive color space based on the RGB color model. ... In color reproduction, including computer graphics and photography, the gamut, or color gamut (pronounced ), is a certain complete subset of colors. ...

On an sRGB display, each solid bar should look as bright as the surrounding striped dither.

sRGB also defines a nonlinear transformation between the intensity of these primaries and the actual number stored. The curve is similar to the gamma response of a CRT display. It is more important to replicate this curve than the primaries to get correct display of an sRGB image. This nonlinear conversion means that sRGB is a reasonably efficient use of the values in an integer-based image file to display human-discernable light levels. Image File history File links Srgbnonlinearity. ...

sRGB is sometimes avoided by high-end publishing professionals because its color gamut is not big enough, especially in the blue-green colors, to include all the colors that can be reproduced in CMYK printing. See RGB color space for the view that Adobe RGB is a preferred colorspace for publishing. Cyan, magenta, yellow, and key (black) CMYK (or sometimes YMCK) is a subtractive color model used in color printing. ... An RGB color space is any additive color space based on the RGB color model. ... The Adobe RGB color space is an RGB color space developed by Adobe Systems in 1998. ...

Specification of the transformation

The forward transformation (CIE xyY or CIE XYZ to sRGB)

The first step in the calculation of sRGB tristimulus values from the CIE XYZ tristimulus values is a linear transformation, which may be carried out by a matrix multiplication.^[1] Note that these linear values are not  the final result. In the study of the perception of color, one of the first mathematically defined color spaces was the CIE XYZ color space (also known as CIE 1931 color space), created by the International Commission on Illumination (CIE) in 1931. ...

Note also, that if the CIE xyY color space values are given (where x, y are the chromaticity coordinates and Y is the luminance), they must first be transformed to CIE XYZ tristimulus values by: Luminance (also called luminosity) is a photometric measure of the density of luminous intensity in a given direction. ...

The intermediate parameters R_linear, G_linear and B_linear for in-gamut colors are in the range [0,1]. The linear values are usually clipped to that range, with display white represented as (1,1,1); the corresponding original XYZ values are such that white is D65 with unit luminance (X,Y,Z = 0.9505, 1.0000, 1.0890).

sRGB was designed to reflect a typical real-world monitor with a gamma of 2.2, and the following formula transforms the linear values into sRGB. Let C_linear be R_linear, G_linear, or B_linear, and C_srgb be R_srgb,G_srgb or B_srgb:

• where

These gamma corrected values are in the range 0 to 1. If values in the range 0 to 255 are required, e.g. for video display or 8-bit graphics, the usual technique is to multiply by 255 and round to an integer.

The reverse transformation

Again the sRGB component values R_srgb, G_srgb, B_srgb are in the range 0 to 1. (A range of 0 to 255 can simply be divided by 255).

where

Theory of the transformation

The transformation was designed to approximate a gamma of about 2.2, but with a linear portion near zero to avoid having an infinite slope at K=0, which can cause numerical problems. The condition that g(K) match at some K₀ is Example of CRT gamma correction Plot of the sRGB standard gamma-expansion nonlinearity (red), and its local gamma value, slope in log–log space (blue). ...

where the standard value of φ = 12.92 which was used above, yields K₀=0.04045.. and this is the transformation used. If we impose the condition that the slope match as well then we must have

We now have two equations. If we take the two unknowns to be K₀ and φ then we can solve to give K₀=0.03928.. and φ=12.9232... These values are sometimes used for the sRGB specification, although they are not standard.

Usage

As the recommended color space for the Internet, sRGB should be used for editing and saving all images intended for publication to the WWW; however, due to sRGB's somewhat limited gamut, images intended for professional printing via a fully color-managed workflow, e.g., prepress output, should choose another color space such as Adobe RGB (1998), which allows for a wider gamut. Digital image editing is the process of altering digital images, whether they be digital photographs or other types of digitally represented images. ... In color reproduction, including computer graphics and photography, the gamut, or color gamut (pronounced ), is a certain complete subset of colors. ... Prepress. ... The Adobe RGB color space is an RGB color space developed by Adobe Systems in 1998. ...

Images intended for the Internet and created in one of the other color spaces may be converted to sRGB when editing, using a suitable editing program, e.g., Paint Shop Pro or Adobe Photoshop; ideally, the original non-sRGB file should be saved and the conversion to sRGB done on a copy, as some loss of image information occurs when converting to the narrower color space. Paint Shop Pro (PSP) is a bitmap graphics editor and vector graphics editor for computers running the Microsoft Windows operating system that was originally published by Minneapolis-based Jasc Software. ... “Photoshop” redirects here. ...

Due to the standardization of sRGB on the Internet, on computers, and on printers, many low- to medium-end consumer digital cameras and scanners use sRGB as the default (or only available) working color space. Used in conjunction with an inkjet printer, an sRGB image produces what is often regarded as satisfactory for home use. However, consumer-level camera LCDs are typically uncalibrated, meaning that even though the image is being labelled as sRGB, one can't conclude that the image is color-accurate on the LCD. Digital cameras are a remarkable advance in technology. ... In computing, a scanner is a device that analyzes an image, printed text, or handwriting, or an object (such as an ornament) and converts it to a digital image. ... Default in computer science refers to a default setting or value automatically assigned to a programme or device. ... Inkjet printers are a type of computer printer that operates by propelling tiny droplets of liquid ink onto paper. ...

The two dominant programming interfaces for 3D graphics, OpenGL and Direct3D, have both incorporated sRGB. OpenGL 2.1 incorporates sRGB textures first introduced by the EXT_texture_sRGB extension. OpenGL's EXT_texture_sRGB extension supports rendering into framebuffers assuming either a linear or sRGB color space. DirectX 9 supports sRGB textures and rendering into sRGB surfaces using Direct3D. OpenGL (Open Graphics Library) is a standard specification defining a cross-language cross-platform API for writing applications that produce 3D computer graphics (and 2D computer graphics as well). ... This article or section does not cite its references or sources. ... Microsoft DirectX (Direct eXtension) is a collection of application programming interfaces for handling tasks related to multimedia, especially game programming and video, on Microsoft platforms. ...

References

• IEC 61966-2-1:1999 is the official specification of sRGB. It provides viewing environment, encoding, and colorimetric details.
• Amendment A1:2003 to IEC 61966-2-1:1999 describes an analogous sYCC encoding for YCbCr color spaces, an extended-gamut RGB encoding, and a CIELAB transformation.
• The fourth working draft of IEC 61966-2-1 is available online, but is not the complete standard.

1. ^ sRGB description with XYZ conversion formula

A colorimeter is device used to measure the absorbance of a specific solution. ... A colour image and the Y, Cb and Cr elements of it. ... In color reproduction, including computer graphics and photography, the gamut, or color gamut (pronounced ), is a certain complete subset of colors. ... CIE L*a*b* (CIELAB) is the most complete color model used conventionally to describe all the colors visible to the human eye. ...

External links

• International Color Consortium
• Archive copy of http://www.srgb.com, now unavailable, containing much information on the design, principles and use of sRGB
• A Standard Default Color Space for the Internet - sRGB
• OpenGL extension for sRGB textures
• Comparison of sRGB and AdobeRGB