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color space

The acquisition, processing and output of color representations is based on color models. The color models form an optimization of what can theoretically be represented in terms of colors. This color range is called color space or gamut and depends on the color temperatures or coordinate values of the individual primary colors.

A color space is defined as the set of colors that can be recognized or represented by peripheral devices - both input and output devices.

Since the light-converting sensors and color filters in the input devices of scanners, digital cameras, and video cameras have their own characteristics and hystereses, and also do not represent exactly the values that theory dictates, color detection can only ever be an approximation to the color models. The same applies to the output devices, such as monitors, projectors, displays and color printers. Here, the wavelengths of the primary colors red, green, blue( RGB) of the phosphors, projector lamps and color filters, as well as the characteristics and intensity of the printer inks, play a decisive role.

RGB and CMY color space in the color wheel

RGB and CMY color space in the color wheel

However, the detection and representation cannot cover a larger color spectrum than the color models theoretically specify. The representable color range of the devices is their color space and this is always within the color space of the corresponding color model. The color space of the peripheral devices includes all colors that can be reproduced. It is therefore device-dependent and is displayed in the color wheel in certain printer programs.

Extension of the color spaces

Color spaces of SMPTE, EBU (PAL), NTSC and UHDTV

Color spaces of SMPTE, EBU (PAL), NTSC and UHDTV

With other color spaces such as the xvYCC color space, RGBW (White), RGBY (Yellow), RGBCY(Cyan, Yellow) and backlights with Wide Color Gamut(WCG), the RGB color space of displays can be extended to include almost all colors found in nature. One of the most extensive color spaces is that defined in BT.2020 for Ultra HDTV, which covers about 76% of all colors that can be represented in the CIE color space. In total, there are between 30 and 40 different color models or color spaces.

Color spaces are different for the same color models and depend on the wavelengths of the primary colors used, which can vary. To achieve consistent color reproduction with a wide color gamut from image capture to image output, standardized color spaces are used. These inevitably require high-quality hardware technology and are used exclusively in professional image processing. The situation is different in consumer electronics, where color palettes with reduced color spaces are used. One such color space is that of standard RGB( sRGB). With standard RGB, there is a defined color space, but not all computer and consumer electronics manufacturers use it.

The color space is described by the ICC color profile from the International Color Consortium, a standardized data set. The user recognizes this by the extension *.icc.

Englisch: color space
Updated at: 20.04.2013
#Words: 477
Links: color, space (SP), output devices, light, digital
Translations: DE

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