A comparison of different color spaces.

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 (e. 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 In Mathematics, a tuple is a Sequence (also known as an "ordered list" of values called the components of the tuple g. RGB and CMYK are color models). CMYK (short for '''c'''yan, '''m'''agenta, '''y'''ellow, and k ey ( Black) and often referred to as process color However, a color model with no associated mapping function to an absolute color space is a more or less arbitrary color system with no connection to any globally-understood system of colour interpretation. 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

Adding a certain mapping function between the color model and a certain reference color space results in a definite "footprint" within the reference color space. This "footprint" is known as a gamut, and, in combination with the color model, defines a new color space. In color reproduction including Computer graphics and Photography, the gamut, or color gamut (pronounced /ˈgæmət/ is a certain complete For example, Adobe RGB and sRGB are two different absolute color spaces, both based on the RGB model. The Adobe RGB color space is an RGB color space developed by Adobe Systems in 1998. sRGB is a standard RGB (Red Green Blue color space created cooperatively by HP and Microsoft for use on monitors printers and the Internet 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

In the most generic sense of the definition above, color spaces can be defined without the use of a color model. These spaces, such as Pantone, are in effect a given set of names or numbers which are defined by the existence of a corresponding set of physical color swatches. Pantone Inc is a corporation headquartered in Carlstadt, New Jersey, USA This article focuses on the mathematical model concept.

## Understanding the concept

A comparison of RGB and CMYK color models.

A wide range of colors can be created by the primary colors magenta, cyan, and yellow, if working with paints. Primary colors are sets of Colors that can be combined to make a useful range ( Gamut) of colors Those colors then define a color space. We can specify the amount of magenta color as the X axis, the amount of cyan as the Y axis, and the amount of yellow as the Z axis, giving us a three-dimensional space, wherein every possible color has a unique position. In Mathematics and its applications a coordinate system is a system for assigning an n - Tuple of Numbers or scalars to each point

However, this is not the only color space. For instance, when colors are displayed on a computer monitor, they are usually defined in the RGB (red, green and blue) color space. This is another way of making the same colors, and red, green and blue can be considered as the X, Y and Z axes. Another way of making the same colors is to use their hue (X axis), their saturation (Y axis), and their brightness (Z axis). 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 Brightness is an attribute of Visual perception in which a source appears to emit or reflect a given amount of Light. This is called the HSV color space. HSL and HSV are two related representations of points in an RGB color space, which attempt to describe perceptual color relationships more accurately than Many color spaces can be represented as three-dimensional (X,Y,Z) values in this manner, but some have more, or fewer dimensions, and some cannot be represented in this way at all.

## Notes

When formally defining a color space, the usual reference standard is the CIELAB or CIEXYZ color spaces, which were specifically designed to encompass all colors the average human can see. 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

Since "color space" is a more specific term for a certain combination of a color model plus a color mapping function, the term "color space" tends to be used to also identify color models, since identifying a color space automatically identifies the associated color model. Informally, the two terms are often used interchangeably, though this is strictly incorrect. For example, although several specific color spaces are based on the RGB model, there is no such thing as the RGB color space.

Since any color space defines colors as a function of the absolute reference frame, color spaces, along with device profiling, allow reproducible representations of color, in both analogue and digital representations. 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 digital system uses discrete (discontinuous values usually but not always Symbolized Numerically (hence called "digital" to represent information for

## Conversion

Main article: Color translation

Color space conversion is the translation of the representation of a color from one basis to another. In digital imaging systems color management is the controlled conversion between the Color representations of various devices such as Image scanners Digital This typically occurs in the context of converting an image that is represented in one color space to another color space, the goal being to make the translated image look as similar as possible to the original.

## Density

The RGB color model is implemented in different ways, depending on the capabilities of the system used. By far the most common general-used incarnation as of 2006 is the 24-bit implementation, with 8 bits, or 256 discrete levels of color per channel. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. 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 Color digital images are made of Pixels and pixels are made of combinations of Primary colors A channel in this context is the grayscale image of the same Any color space based on such a 24-bit RGB model is thus limited to a gamut of 256×256×256 ≈ 16. In color reproduction including Computer graphics and Photography, the gamut, or color gamut (pronounced /ˈgæmət/ is a certain complete 7 million colors. Some implementations use 16 bits per component for 48 bits total, resulting in the same range with a larger number of distinct colors. This is especially important when working with wide-gamut color spaces (where most of the more common colors are located relatively close together), or when a large number of digital filtering algorithms are used consecutively. The same principle applies for any color space based on the same color model, but implemented in different bit depths.

## Partial list of color spaces

CIE 1931 XYZ color space was one of the first attempts to produce a color space based on measurements of human color perception (earlier efforts were by James Clerk Maxwell, König & Dieterici, and Abney at Imperial College)[1] and it is the basis for almost all other color spaces. This is a list of color spaces and their uses from the Color space article 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 James Clerk Maxwell (13 June 1831 &ndash 5 November 1879 was a Scottish mathematician and theoretical physicist. Imperial College London (officially The Imperial College of Science Technology and Medicine as given in its Royal Charter It is one of only three universities to have reached Derivatives of the CIE XYZ space include CIELUV, CIEUVW, and CIELAB. In Colorimetry, the CIE 1976 ( L*, u*, v*) color space, also known as the CIELUV color space, is a Color space adopted by The CIE 1964 color space, CIEUVW ("U^*V^*W^*" is based on the CIE 1960 UCS: U^*=13W^*(u-u_0 \quad V^*=13W^*(v-v_0 \quad W^*=25Y^{1/3}-17 A Lab color space is a color-opponent space with dimension L for lightness and a and b

### Generic color models

Main article: Color models
Subtractive color mixing

RGB uses additive color mixing, because it describes what kind of light needs to be emitted to produce a given color. 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 An RGB color space is any additive Color space based on the RGB color model. An additive color model involves Light emitted directly from a source or illuminant of some sort Light is added together to create form from out of the darkness. RGB stores individual values for red, green and blue. RGBA is RGB with an additional channel, alpha, to indicate 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

Common color spaces based on the RGB model include sRGB, Adobe RGB and Adobe Wide Gamut RGB. 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. The Adobe Wide Gamut RGB color space is an RGB color space developed by Adobe Systems as an alternative to the SRGB color space and subsequently abandoned

CMYK uses subtractive color mixing 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. CMYK (short for '''c'''yan, '''m'''agenta, '''y'''ellow, and k ey ( Black) and often referred to as process color A subtractive color model explains the mixing of Paints Dyes Inks and natural colorants to create a range of Colors where each such color An ink is a Liquid containing various Pigments and/or Dyes used for coloring a surface to produce an Image, text, or 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. CMYK (short for '''c'''yan, '''m'''agenta, '''y'''ellow, and k ey ( Black) and often referred to as process color 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).

YIQ was formerly used in NTSC (North America, Japan and elsewhere) television broadcasts for historical reasons. 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 This system stores a luminance value with two chrominance values, corresponding approximately to the amounts of blue and red in the color. It is similar to the YUV scheme used in most video capture systems[2] and 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. PAL, short for Phase Alternating Line, is a colour -encoding system used in Broadcast television systems in large parts of the world SECAM, also written SÉCAM ( Séquentiel couleur à mémoire, French for "Sequential Color with Memory" is an analog color television system The YDbDr scheme used by SECAM television is rotated in another way. 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 scaled version of YUV. YPBPR is a Color space used in Video electronics in particular in reference to Component video cables It is most commonly seen in its digital form, YCbCr, used widely in video and image compression schemes such as MPEG and JPEG. 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 Video compression refers to reducing the quantity of Data used to represent video images and is a straightforward combination of Image compression and Motion Image compression is the application of Data compression on Digital images In effect the objective is to reduce redundancy of the image data in order to be able to 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

xvYCC is a new international digital video color space standard published by the IEC (IEC 61966-2-4). xvYCC or Extended- Gamut YCC is a Color space that can be used in the Video electronics of television sets to support 1 The International Electrotechnical Commission ( IEC) is a not-for-profit, non-governmental international Standards organization that prepares and publishes It is based on the ITU BT. 601 and BT.709 standards but extends the gamut beyond the R/G/B primaries specified in those standards. ITU-R Recommendation BT709, more commonly know by the abbreviations Rec

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. HSL and HSV are two related representations of points in an RGB color space, which attempt to describe perceptual color relationships more accurately than 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 or HSI (hue, saturation, intensity) is quite similar to HSV, with "lightness" replacing "brightness". HSL and HSV are two related representations of points in an RGB color space, which attempt to describe perceptual color relationships more accurately than HSL and HSV are two related representations of points in an RGB color space, which attempt to describe perceptual color relationships more accurately than 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.

### Special-purpose color spaces

• The RG Chromaticity space is used in Computer vision applications, and shows the color of light (red, yellow, green etc. In Colorimetry, the Munsell color system is a Color space that specifies Colors based on three color dimensions Hue, value ( lightness Flag of Swedensvg|thumb|250px|The colors of the Swedish flag are officially established to be NCS 0580-Y10R for the shade of yellow and NCS 4055-R95B for the shade of blue]]The Natural The rg chromaticity space is a two-dimensional Color space in which there is no color intensity information Computer vision is the science and technology of machines that see ), but not its intensity (dark, bright).

### 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.

## Notes

1. ^ William David Wright, "50 years of the 1931 CIE Standard Observer. The RG or red-green color space is a Color space that uses only two colors Red and Green. Technicolor is the trademark for a series of color film processes pioneered by Technicolor Motion Picture Corporation Die Farbe, 29:4/6 (1981).
2. ^ Dean Anderson. Color Spaces in Frame Grabbers: RGB vs. YUV. Retrieved on 2008-04-08. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 217 - Roman Emperor Caracalla is Assassinated (and succeeded by his Praetorian

## References

• R. W. G. Hunt, The Reproduction of Colour in Photography, Printing & Television, 5th Ed. Fountain Press, England, 1995. ISBN 0-86343-381-2
• Mark D. Fairchild, Color Appearance Models, Addison-Wesley, Reading, MA (1998). ISBN 0-201-63464-3
• Charles A. Poynton, Introduction to Video Colour Spaces
• J. Morovic, Color Gamut Mapping, Wiley, 2008. ISBN 978-0-470-03032-5