Useful Terms and Definitions

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ANSI — American National Standards Committee, sole United States Member body to the iso. Facilitates United States Standardization policy developments, accredits national standards developers, promotes us standards interests globally and provides information and training on standardization

Apparent Dot Area (ADA) — Tone Value, the dot or tone percentage amount of a printed tint as measured on a densitometer utilizing the Murray-Davies equation

BIT — Abbreviation for binary digit. The smallest unit of information in a binary system, a bit is the fundamental unit of information used in computers. A bit element is a 1 signaling on or a 0 signaling off

BITMAP — A computerized image made up of dots or pixels. While satisfactory for pixel-based screen displays bitmap images can give a jagged appearance on paper or film. For high quality print output, bitmap resolution is an important factor

CEPS — Color Electronic Prepress System — A high quality, proprietary computer-based system that may include equipment for page make-up, scanning color separations, displaying color and making color corrections. This is to be contrasted with pc-based color scanning and manipulation systems often referred to as desktop publishing systems (DTP)

CGATS — Committee for Graphic Arts Technologies Standards. The mission of cgats is to have the entire scope of printing and publishing technologies represented in one national standardization and coordination effort

CHROMA — The attribute of visual perception in accordance with which an area appears saturated with a particular color or hue

CIE — International Commission on Illumination, an international organization whose visual color models have become the basis for all colorimetric measurements
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CIELAB — Color space defined by CIE in which values L*, a*, b* are plotted at right angles to one another to form a three dimensional coordinate system. Equal distance in the space approximately represents equal color differences. Value L* represents Lightness, value a* represents the Red/Green axis and value b* represents the yellow/blue axis. A popular color space for use in measuring reflective and transmissive objects

COLOR MANAGEMENT — A framework to provide device calibration, device characterization and device profile building methods

CONTRAST — The level of variation between light and dark areas in an image

CONTROL LIMITS — The amount of acceptable variation in press capabilities over the course of a press run

CMY — Color space defined by the subtractive primaries cyan, magenta and yellow. In printing, black (defined by "K") is added to make up for deficiencies in real-world CMY inks.

CTP — Computer-To-Plate

D65 — The CIE standard illumination that represents a color temperature of 6504°K. This is the color temperature that is most widely used in graphic arts industry viewing booths

DDAP — Digital Distribution of Advertising Publications

DDCP — Direct Digital Color Proofing

DELTA e (error) — In color tolerancing, the symbol e is used to express Delta error, the total color difference computed using a color difference equation. The equation is calculated as the square root of the combined squares of the chromaticity differences (L*, a*, b*)

DENSITOMETER — A sensitive, photoelectric instrument that measure the density of images or colors

DEVICE INDEPENDENT — Describes a color space that can be defined using the full gamut of human vision, as defined by a standard observer, independent of the color rendering capabilities of any specific device

DTP — Desktop Publishing

EDI — Electronic Data Interchange

ELECTRONIC MECHANICALS — Digital page layout files created on a desktop publishing system. Electronic mechanicals commonly contain text and graphics in EPS, TIFF or similar file formats

EPS — Encapsulated Postscript

FILE FORMAT — A set of instructions that describe how to store, access or transmit digital information. Being able to match the format of data created in one program to what can be received by another is the basis for compatibility

GAMUT — The range of colors that can be defined by a color model or generated by a specific device

GCA — Graphic Communication Association

GATF — Graphic Arts Technical Foundation

GCR — Gray Component Replacement, refers to a color separation technique that uses the black printer for the gray component, or achromatic portion of any color instead of the third primary color

GRACOL — General Requirements for Applications in Commercial Offset Lithography

HARD DOT — A halftone dot that has a hard, crisp edge without the fringe seen with the soft dot. The halftone dot also has a fairly uniform density over its entire surface

ICC — International Color Consortium

IMAGESETTER — A general term used for devices that generate graphic arts film or plates from electronic data sources

ISO — International Organization of Standardization — a worldwide federation of standards bodies from over 100 countries. Its mission is to promote the development of standardization and related activities in the world with a view to facilitating the international exchange of goods and services, and to developing cooperation in the spheres of intellectual, scientific, technological and economic activity. The technical committee responsible for the graphic arts is TC130

IT.8 — Series of test targets developed for the color characterization of electronic material used in printing reproduction. Established by ANSI.

LASER — Acronym for Light Amplification by Stimulated Emission of Radiation. The amplification of only one frequency of light within the spectrum to create a directional, intense beam. Lasers are used in imagesetters to create images on lithographic film.

LOSSLESS COMPRESSION — Data compression methods that rearrange data or re-code data in a more compact fashion and lose no information when decompressed

LOSSY COMPRESSION — Data compression methods (such as JPEG) that selectively discard repetitive information to decrease file sizes. Depending on the amount of compression requested, the lost information may or may not be noticeable. At high compression rates such as 25:1, degradation can easily be seen.

NANOMETER — Unit of length equal to a 10E-9 meter, or one millionth of a millimeter. Wavelengths are measured in nanometers

OFF PRESS PROOF — A four-color proof generated before the production press run and before, or instead of a press proof. An off-press proof can be produced through photomechanical, electrostatic or electronic means

OVERPRINT — Overprints are areas of color where two or more inks have been printed, one atop the other.

PDF — Portable Document Format

PICT — a standard Macintosh format for encoding illustrations. Not appropriate for high-end output

PIXEL — Abbreviation for picture element. The smallest unit that can be sensed, manipulated, or output by a digital system or displayed on a computer screen. More pixels per inch mean higher resolution

PROCESS CONTROL — Using densitometric and colorimetric measurement data from press sheet color bars to monitor press performance throughout the press run. Data is analyzed in relation to established control limits

RIP — Raster Image Processor. The process of interpreting a page description language, such as PostScript, to a raster format at the resolution and in the format required for a specific output device or imagesetter. The RIP may also incorporate machine-specific instruction, and the RIP may reside either in the imagesetter or in a separate computer system

RESOLUTION — The degree of image sharpness that can be reproduced by a piece of equipment. Resolution is measured in dots per inch (DPI) or pixels per square millimeter. On high end scanners resolution is counted both vertically and horizontally. The higher the resolution, the better the image detail appears and the larger the file becomes requiring more computer memory and longer processing times

RGB — Color space defined by the additive color primaries red, green, and blue.

SATURATION — The attribute of color perception that expresses the amount of departure from the neutral gray of the same lightness. Also referred to as chroma

SOFT DOT — A halftone dot that does not have uniform density over its entire surface and may also have a soft fringe. This is an important area for calibration and quality control checks since the small variances in dot size can create dramatic changes in color reproduction

SPECTROPHOTOMETER — An instrument that measures the characteristics of light reflected from or transmitted through an object, which is interpreted as spectral data.

SWOP — Specifications for Web Offset Publications

TIFF/IT-P1 — Tag Image File Format for Image Technology

TOLERANCE — The amount of acceptable difference between a known correct standard (usually the customer’s specifications) and a set of measured samples

TOTAL DOT GAIN — Tonal Value increase — difference between ADA or tone value on the print and the corresponding tone value on the separation film or in the electronic file. The term Total Dot Gain applies only to halftone produced by the dot patterns. (ISO 12647)

UCR — Under color removal refers to the reduction of chromatic colors (yellow, cyan, magenta) in the dark or near neutral shadow areas in order to reduce the total area coverage and ink film thickness to improve trapping and allow better shadow detail and more consistent printing reproduction

UGRA — Association for the Promotion of Research in the Graphic Arts Industry.