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It has been suggested that this article or section be merged into color space. (Discuss) |
This is a list of color spaces and their uses from the color space article. A color space consists of a color model along with a specific mapping of that model onto an absolute color space. There are a large number of color spaces in use in the world today.
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Models
There are 5 major models, that sub-divides into others, they are: CIE, RGB, YUV, HSL/HSV, and CMYK.
CIE
CIE 1931 XYZ
(aka "CIE 1931") The first attempt to produce a color space based on measurements of human color perception and it is the basis for almost all other color spaces.
CIELUV
A modification of "CIE 1931 XYZ" to display color differences more conveniently. The CIELUV space is especially useful for additive mixtures of lights, due to its linear addition properties [1].
CIELAB
The intention of CIELAB (or L*a*b* or Lab) is to produce a color space that is more perceptually linear than other color spaces. Perceptually linear means that a change of the same amount in a color value should produce a change of about the same visual importance. CIELAB has almost entirely replaced an alternative related Lab color space "Hunter Lab". This space is commonly used for surface colours, but not for mixtures of (transmitted) light [1].
CIEUVW
Measurements over a larger field of view than the "CIE 1931 XYZ" color space which produces slightly different results.
RGB
RGB
RGB (Red, Green, Blue) describes what kind of light needs to be emitted to produce a given color. Light is added together to create form from out of the darkness. RGB stores individual values for red, green and blue. RGB is not a color space, it is a color model. There are many different RGB color spaces derived from this color model, some of which appear below.
RGBA is RGB with an additional channel, alpha, to indicate transparency.
sRGB
The sRGB color space, or standard RGB (Red Green Blue), is an RGB color space created cooperatively by Hewlett-Packard and Microsoft Corporation for use on the Internet. It has been endorsed by the W3C, Exif, Intel, Pantone, Corel, and many other industry players. It 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.
sRGB is intended as a common color space for the creation of images for viewing on the Internet and World Wide Web (WWW), the resultant color space chosen using a gamma of 2.2, the average response to linear voltage levels of CRT displays at that time.
Adobe RGB
The Adobe RGB color space is an RGB color space developed by Adobe Systems in 1998. It was designed to encompass most of the colors achievable on CMYK color printers, but by using RGB primary colors on a device such as the computer display. The Adobe RGB color space encompasses roughly 50% of the visible colors specified by the Lab color space, improving upon the gamut of the sRGB color space primarily in cyan-greens.
Adobe Wide Gamut RGB
The Adobe Wide Gamut RGB color space is an RGB color space developed by Adobe Systems as an alternative to the standard sRGB color space. It is able to store a wider range of color values than sRGB. The Wide Gamut color space is an expanded version of the Adobe RGB color space, developed in 1998. As a comparison, the Adobe Wide Gamut RGB color space encompasses 77.6% of the visible colors specified by the Lab color space, whilst the standard Adobe RGB color space covers just 50.6%.
One of the downsides to this color space is that approximately 8% of the colors representable are imaginary colors that do not exist and are not representable in any medium [1]. This means that potential color accuracy is wasted for reserving these unnecessary colors.
Other RGB spaces
Other RGB spaces are possible by selection of other end points of the covered spectrum.
Luminance plus chrominance
YIQ, YUV, YDbDr
YIQ was formerly used in NTSC (North America, Japan and elsewhere) television broadcasts for historical reasons. This system stores a luminance value with two chrominance values, corresponding approximately to the amounts of blue and red in the color. It corresponds closely to the YUV scheme used in PAL (Australia, Europe, except France, which uses SECAM) television except that the YIQ color space is rotated 33° with respect to the YUV color space. The YDbDr scheme used by SECAM television is rotated in another way. (work needed)
YPbPr, YCbCr
YPbPr is a scaled version of YUV. It is most commonly seen in its digital form, YCbCr, used widely in video and image compression schemes such as MPEG and JPEG.
xvYCC
xvYCC is a new international digital video color space standard based on the ITU BT.601 and BT.709 standards but with the color gamut extended beyond the R/G/B primaries specified in those standards.
Hue and saturation
HSV
(hue, saturation, value), also known as HSB (hue, saturation, brightness) is often used by artists because it is often more natural to think about a color in terms of hue and saturation than in terms of additive or subtractive color components. HSV is a transformation of an RGB colorspace, and its components and colorimetry are relative to the RGB colorspace from which it was derived.
HSL
(hue, saturation, lightness/luminance), also known as HLS, HSI (hue, saturation, intensity) or TSD (hue, saturation, darkness) is quite similar to HSV, with "lightness" replacing "brightness". The difference is that the brightness of a pure color is equal to the brightness of white, while the lightness of a pure color is equal to the lightness of a medium gray.
CMYK
CMYK
CMYK is used in the printing process, because it describes what kind of inks need to be applied so the light reflected from the substrate and through the inks produces a given color. One starts with a white substrate (canvas, page, etc), and uses ink to subtract color from white to create an image. CMYK stores ink values for cyan, magenta, yellow and black. There are many CMYK colorspaces for different sets of inks, substrates, and press characteristics (which change the dot gain or transfer function for each ink and thus change the appearance).
Commercial color spaces
Special-purpose color spaces
- The RG Chromaticity space is used in Computer vision applications, and shows the color of light (red, yellow, green etc.), but not its intensity (dark, bright).
- LMS color space (long, medium, short), a perceptual color space based on the response functions of the cones in the retina of the eye. It is mostly used in psychometric research.
Obsolete color spaces
Early color spaces had two components. They largely ignored blue light because the added complexity of a 3-component process provided only a marginal increase in fidelity when compared to the jump from monochrome to 2-component color.
- RG for early Technicolor film
- RGK for early color printing
References
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