RGB color space

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Intuition

An RGB color space can be easily understood by thinking of it as "all possible colors" that can be made from three colourants for red, green and blue. Imagine, for example, shining three lights together onto a white wall: one red light, one green light, and one blue light, each with dimmer switches. If only the red light is on, the wall will look red. If only the green light is on, the wall will look green. If the red and green lights are on together, the wall will look yellow. Dim the red light some and the wall will become more of a yellow-green. Dim the green light instead, and the wall will become more orange. Bringing up the blue light a bit will cause the orange to become less saturated and more whitish. In all, each setting of the three dimmer switches will produce a different result, either in color or in brightness or both. The set of all possible results is the gamut defined by those particular color light bulbs. Swap out the red light bulb for one of a different brand that is slightly more orange, and there will be slightly different gamut, since the set of all colors that can be produced with the three lights will be changed.

An LCD display can be thought of as a grid of thousands of little red, green, and blue light bulbs, each with their own dimmer switch. The gamut of the display will depend on the three colors used for the red, green and blue lights. A wide-gamut display will have very saturated, "pure" light colors, and thus be able to display very saturated, deep colors. compaq armada m700 battery

Applications dell x300 battery

RGB is a convenient color model for computer graphics because the human visual system works in a way that is similar though not quite identical to an RGB color space. The most commonly used RGB color spaces are sRGB and Adobe RGB (which has a significantly larger gamut). Adobe has recently developed another color space called Adobe Wide Gamut RGB, which is even larger, in detriment to gamut density. rechargeable lithium aa batteries

As of 2007, sRGB is by far the most commonly used RGB color space, particularly in consumer grade digital cameras, HD video cameras, and computer monitors. HDTVs use a similar space, sharing the sRGB primaries, commonly called Rec. 709. sRGB is considered adequate for most consumer applications. Having all devices use the same color space is convenient in that an image does not need to be converted from one color space to another before being displayed. However, sRGB's limited gamut leaves out many highly saturated colors that can be produced by printers or in film, and thus is not ideal for some high quality applications. The wider gamut Adobe RGB is being built into more medium-grade digital cameras, and is favored by many professional graphic artists for its larger gamut.

Specifications

RGB spaces are generally specified by defining three primary colors and a white point. In the table below the three primary colors and white points for various RGB spaces are given. The primary colors are specified in terms of their CIE 1931 color space chromaticity coordinates (x,y).

Some RGB color space parameters (from Susstrunk, Buckley and Swen 2005)

Color Space

Gamut

White Point

Primaries

xR

yR

xG

yG

xB

yB

ISO RGB

Limited

floating

floating

Extended ISO RGB

Unlimited (signed)

floating

floating

sRGB,

HDTV (ITU-R BT.709-5)

CRT

D65

0.64

0.33

0.30

0.60

0.15

0.06

scRGB

Unlimited (signed)

D65

0.64

0.33

0.30

0.60

0.15

0.06

ROMM RGB

Wide

D50

0.7347

0.2653

0.1596

0.8404

0.0366

0.0001

Adobe RGB 98

CRT

D65

0.64

0.34

0.21

0.71

0.15

0.06

Apple RGB

CRT

D65

0.625

0.34

0.28

0.595

0.155

0.07

NTSC (FCC 1953, ITU-R BT.470-2 System M)

CRT

C

0.67

0.33

0.21

0.71

0.14

0.08

NTSC (1979)

(SMPTE 170M/240M, SMPTE RP 145 "SMPTE C")

CRT

D65

0.63

0.34

0.31

0.595

0.155

0.07

PAL/SECAM

(EBU 3213, ITU-R BT.470-2 System B, G)

CRT

D65

0.64

0.33

0.29

0.60

0.15

0.06

Adobe Wide Gamut RGB

Wide

D50

0.735

0.265

0.115

0.826

0.157

0.018

CIE (1931)

Wide

E

0.7347

0.2653

0.2738

0.7174

0.1666

0.0089

The CIE 1931 color space standard defines both the CIE RGB space, which is an RGB color space with monochromatic primaries, and the CIE XYZ color space, which works like an RGB color space except that it has non-physical primaries that can not be said to be red, green, and blue.

See also

Web colors

External links

Pascale, Danny. "A Review of RGB color spaces...from xyY to R'G'B'" (PDF). http://www.babelcolor.com/download/A%20review%20of%20RGB%20color%20spaces.pdf. Retrieved 2008-01-21. 

Susstrunk, Buckley and Swen. "Standard RGB Color Spaces" (PDF). http://infoscience.epfl.ch/getfile.py?mode=best&recid=34089. Retrieved November 18, 2005. 

ShootSmarter.com. "sRGB vs Adobe RGB: The Truth". http://www.shootsmarter.com/infocenter/wc025.html. Retrieved November 18, 2005.  - a summary of the practical aspects of using the two spaces (requires membership - membership free if email provided.)

Lindbloom, Bruce. "RGB Working Space Information". http://www.brucelindbloom.com/index.html?WorkingSpaceInfo.html. Retrieved November 18, 2005. 

Colantoni, Philippe. "RGB cube transformation in different color spaces". http://www.couleur.org/index.php?page=rgbcube. 

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Color space

List of color spaces  Color models

CIE

XYZ  L*a*b*  L*u*v*  Yuv  U*V*W*

RGB

color spaces  sRGB  Adobe  Wide Gamut  ProPhoto  scRGB

YUV

YUV (PAL)  YDbDr (SECAM)  YIQ (NTSC)  YCbCr  YPbPr  xvYCC

Other

LMS  HSL, HSV  CMYK  CcMmYK  Hexachrome  RYB  Munsell  NCS  Pantone  RAL

OSA-UCS  Coloroid  RG  Ostwald  DIN  PCCS  ABC  DCA  JIS Z8102  ISCC-NBS Imaginary color

See color vision for the vision capacities of organisms or machines.

Categories: Color space