A

Absolute Colorimetric
The rendering intent that leaves colors that fall inside the destination gamut unchanged. Out of gamut colors are clipped. No scaling of colors to destination white point is performed. This intent aims to maintain color accuracy at the expense of preserving relationships between colors, and is useful for seeing how output will look on a non-neutral substrate.

additive color model
The color model in which colors are produced by combining various percentages of red, green, and blue light. In the additive color model, white is produced by mixing 100% of each primary, whereas black is produced the absence (i.e., 0%) of each primary. The additive color model is used by computer monitors to produce their display.

additive primaries
Red, green, and blue (RGB). Lights of these colors, when mixed together in varying intensities, produce any other color in the additive color model.

Adobe Color Engine (ACE)
The color management model created by Adobe Systems, Incorporated that is the default conversion engine used for ICC color-managed color conversions within Adobe applications. Replaces the system level CMS and CMMs for these transformations.

Adobe Gamma
The utility created by Adobe Systems, Incorporated for calibrating and characterizing your monitor, resulting in the creation of an ICC device profile for use in Adobe Photoshop, Adobe InDesign, Adobe Illustrator, and all other ICC-aware applications. For more information on Adobe Gamma, see the technical guide, "Using Adobe Gamma."

Adobe PostScript
An object-oriented page description language developed by Adobe Systems, Incorporated. PostScript is widely used for pixel-based output devices (e.g., imagesetters).

Adobe RGB (1998)
The RGB working space created by Adobe Systems, Incorporated that provides a fairly large gamut of colors and is well-suited for documents that will be converted to CMYK.

Apple ColorSync
The color management system provided by Apple Computer, Inc. for Mac OS computers.

Apple RGB
The RGB working space created by Apple Computer, Inc. that reflects the characteristics of the Apple Standard 13-inch monitor, and is used by a variety of desktop publishing applications.

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C

calibration
The process of setting a device to known color conditions. Calibration must be performed externally for devices whose color characteristics change frequently. For example, calibration must be performed on monitors because phosphors lose brightness over time, and on printers because proofers and other digital printing devices can change output when colorant or paper stock is changed. Calibration is not required for most input devices (e.g., scanners and cameras) since these devices are generally self-calibrating.

characterization
The process of creating an ICC profile that describes the unique color characteristics of a particular device such as a monitor, scanner, color printer, and printing press. Press Profiles may be based on standards such as SWOP. Resultant ICC profiles define the gamut of a device in the context of a device-independent color space so that colors may be mapped to or from the device gamut.

chroma
The quality of a color that is the combination of hue and brightness. In the Munsell system of color notation, chroma indicates the purity of a color as measured along an axis; the farther from the axis, the purer the color. See also saturation.



CIE
The Commission Internationale de l'Eclairage, a standards-setting organization formed to study and promote standards related to color. CIE has produced several influential color models: CIELAB and CIEXYZ.

CIELAB
See L*a*b model.

CIEXYZ
See XYZ model.

clipping
Color shift caused by the inability of one color space to reproduce all the colors of another color space. For example, using a colorimetric rendering intent, any values in the source color space that are outside the gamut of the destination color space are forced into its gamut, or clipped. Colors that are within the gamut of both color spaces are left alone. The result is that two colors that used to be different may now share the same values, which results in visual color shifts. See also non-reproducible colors.

CMYK
Abbreviation for cyan, magenta, yellow, and black; the inks used in process printing. They represent the subtractive color model, where a combination of 100% of each component yields black and 0% of each yields white. Cyan, magenta, and yellow are the subtractive complements of red, green, and blue respectively.

color engine
See Color Management Module (CMM).

color management module (CMM)
Also called a Color Engine, the specific software component (e.g., Apple CMM, Heidelberg CMM, Agfa CMM) in a CMS (e.g., ColorSync) that does the color conversion calculations from one device's color space to that of another using the ICC device profiles. Photoshop 5.x, Illustrator 8.x, and InDesign have their own built-in CMM that serves as the application's default CMM.

color management system (CMS)
A system-level framework that may be used by applications for translating colors from the gamut of one device to the gamut of another device. Apple ColorSync for Mac OS and Microsoft ICM 2.0 for Windows are each an example of a CMS.

color model
The dimensional coordinate system used to numerically describe colors. Some models include RGB, HSB, CMYK, and L*a*b*. For more information, see the technical guide, "Color Models."

color profile
See ICC device profile.

color rendering dictionary (CRD)
A PostScript dictionary, which is the PostScript equivalent of a CMS separations profile, that describes how color is rendered to a specific device. PostScript color management allows the color space of an output device to be stored at the device as a color rendering dictionary, making device-independent output possible.

color space
A particular variant of a color model with a specific gamut or range of colors, which is one of its chief characteristics. For example, within the RGB color model are a number of color spaces like Apple RGB, Adobe RGB (1998), sRGB, etc. While each of these define color by the same three axes (R, G, and B), they differ in gamut as well as other specific characteristics.

colorimeter
A device that measures the luminosity of a few (typically three to eight) specific colors. A colorimeter can be used with software that creates ICC device profiles for monitors. A monitor with an attached hardware calibrator uses a colorimeter.

ColorMatch RGB
The RGB working space that is the native color space of Radius Pressview monitors. This space provides a smaller gamut alternative to Adobe RGB (1998) for print production work.

ColorSync
See Apple ColorSync.

ColorSync CMYK Default
The Default for Documents setting of ColorSync 3.0.1 that specifies the default CMYK working space for applications that query the ColorSync control panel. This working space may be inherited by newer Adobe applications (e.g., Adobe Photoshop 6.0 and Adobe Illustrator 9.0) when you specify "ColorSync Workflow" in the application's Color Settings dialog box.

ColorSync RGB Default
The Default for Documents setting of ColorSync 3.0.1 that specifies the default RGB working space for applications that query the ColorSync control panel. This working space may be inherited by newer Adobe applications (e.g., Adobe Photoshop 6.0 and Adobe Illustrator 9.0) when you specify "ColorSync Workflow" in the application's Color Settings dialog box.

composite printer
The printer used to make a composite color image of a file. This printer can be used for proofing or for final output.

contract proof
The proof (e.g., Dupont WaterProof or Imation MatchPrint) of a color printing job that is the basis of a contract between a printer and a client. The appearance of the contract proof should represent the appearance of final printed piece. See also hard proof.

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D

densitometer
A device that measures the density of exposed film (in transmissive mode) or printed inks (in reflective mode). Densitometers are used to calibrate output devices.

density
The degree of darkness (opacity) of a photographic image. Higher density values represent greater opacity.

device-independent color space
A color model not related to any device, but is instead based on human visual perception as defined by the CIE experiments begun in 1931. Device-independent color spaces contain all colors that may be perceived by a human observer. They are used as the intermediary space known as the profile connection space (PCS) in ICC color conversions, and may also be used to store or transmit color values.

dithering
The technique by which the gap between two pixels is filled with another pixel. The color of the added pixel is an average of two on either side of it to visually smooth the result. Dithering is generally used when not enough colors are available.

dot gain
Measured by the increase in size of a midtone dot, the spreading of dots during platemaking or on a printing press as wet ink is pushed into the paper and possibly absorbed by it.

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E

EPS
Appbreviation for Encapsulated PostScript, the file format based on Adobe PostScript. Primarily used to define vector graphics (i.e., geometrical shapes), it can also be used to contain and provide instructions for rendering image (i.e., pixel-based) data.

Euroscale Coated
The CMYK working space that uses specifications designed to produce quality separations using Euroscale inks under the following printing conditions: 350% total area of ink coverage, positive plate, bright white coated stock.

Euroscale Uncoated
The CMYK working space that uses specifications designed to produce quality separations using Euroscale inks under the following printing conditions: 260% total area of ink coverage, positive plate, uncoated white offset stock.

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F

four-color process
The printing process that reproduces colors by combining, cyan (C), magenta (M), yellow (Y), and black (K) inks. This process is alternately called four-color printing, CMYK printing, or process printing.

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G

gamma
The values produced by a monitor from black to white are nonlinear. If you graph the values, they form a curve, not a straight line. Gamma defines the slope of that curve at halfway between black and white. Gamma adjustment compensates for the nonlinear tonal reproduction of output devices such as monitor tubes. Gray Gamma 1.8 matches the default grayscale display of Mac OS computers. Gray Gamma 2.2 matches the default grayscale display of Windows computers. See also, Adobe Gamma.

gamut
The total range of colors produced by a device. A color is said to be "out of gamut" when its position in one device's color space cannot be directly translated into another device's color space. For example, the total range of colors that can be reproduced with ink on coated paper is greater than that for uncoated newsprint, so the total gamut for uncoated newsprint is said to be smaller than the gamut for coated stock. A typical CMYK gamut is generally smaller than a typical RGB gamut.



GCR
Abbreviation for gray component replacement; the separation technique where black ink is used to replace either a portion of the unwanted component in a saturated color, or a combination of cyan, magenta, and yellow equivalent to the unwanted component. Typically specified to improve color control on older presses. Contrast UCR.

GIF
Acronym for Graphics Interchange Format; a commonly used graphic file format (e.g., for Web pages) developed by Compuserve, Inc. that can be either 1-bit or 8-bit, rendering from 2 to 256 colors or shades of gray.

gray balance
The reduction of magenta and yellow in relationship to cyan required to render a neutral on a CMYK device. Gray balance is required because of ink hue errors. An example of dot percentages that will yield a neutral on a U.S. printing press are 5% cyan, 3% magenta, and 3% yellow for the highlight neutral.

grayscale
(1) The series of tones stepped from white to black and containing no color. (2) The Photoshop image mode used to represent a range of neutral tones, such as those from black-and-white photographic originals.

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H

hard proof
The printed proof of a document created to preview how colors will look when reproduced on a specific output device, usually a commercial printing press. A hard proof may be produced using a laminate contract proofing system (e.g., Imation MatchPrint) or a tightly calibrated digital printer designed for proof creation. Contrast soft proof.

HSB
A three-coordinate, device-independent color model. The HSB coordinates define colors in terms of Hue, Saturation, and Brightness.



Hue
The color reflected from, or transmitted through, an object. It is expressed as an angular position on a standard color wheel. In common use, hue refers to the name of the color such as red, orange, or green.

hue error
Apparent impurities in process (CMYK) inks resulting in the unwanted absorptions of colors that should be transmitted by a given ink, such as green through cyan.

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I

in-RIP
Refers to any process performed within a raster image processor (RIP). Color screening, color management, and trapping are examples of processes that can be performed in-RIP if the RIP supports that process.

International Color Consortium (ICC)
The group established by eight industry vendors (including Adobe Systems) for the purpose of creating, promoting, and encouraging the standardization and evolution of an open, vendor-neutral, cross-platform color management system architecture. For more information, visit the ICC Web site at www.color.org.

ICC device profile
A file that describes how a particular device reproduces color. The profile defines device gamut in the context of a device-independent color space. Profiles can be either generic or custom. Generic profiles are created by the device manufacturer who examines the color characteristics of a group of the same devices under controlled conditions, and then uses this information to create a profile. Custom device profiles are created for an individual device, using a color-measuring instrument (e.g., a spectrophotometer or colorimeter) and device-profiling software.

International Standards Organization (ISO)
The group that creates and maintains international standards for technology, including computer technology.

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J

Japan Standard
The RGB working space that uses specifications designed to produce quality separations using Japan Standard inks under the following printing conditions: 300% total area ink coverage, positive plate, coated publication-grade stock.

JPEG
Acronym for Joint Photographic Experts Group. Commonly used to indicate a pixel-based graphic file format, JPEG is actually a compression method used mostly for continuous tone images.

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K

Kelvin

The unit of measure used for color temperature. Kelvin is an extension of the centigrade scale down to Absolute Zero (0 K). Light toward the red end of the spectrum is cooler on the Kelvin scale. The light produced by standard household light bulbs is approximately 2,800 K. Standard color-viewing stations used in the graphic arts industry in the U.S illuminate samples with 5,000 K light. In Europe and other geographies, 6,500 K light is the standard.



Kodak CMS

An application-level CMS developed by Kodak for Mac OS and Windows. The most current version uses ICC device profiles.

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