Darts:

See also – Comets.

D50:

The CIE standard illuminant that represents a color temperature of 5000°K. This is the color temperature that is most widely used in graphic arts industry viewing booths.

D65:

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

Dancer:

A moving roller sensor used for feedback control of web tension.

Data Compression:

Technique of reducing the amount of storage required to hold a digital file to reduce the disk space the file requires and allow it to be processed or transmitted more quickly.

Daylight illuminants (CIE):

Series of illuminant spectral power distribution curves based on measurements of natural daylight and recommended by the CIE in 1965. Values are defined for the wavelength region 300 to 830nm. They are described in terms of the correlated color temperature. The most important is D65 because of the closeness of its correlated color temperature to that of illuminant C, 6774K. D75 bluer than D65 and D55 yellower than D65 are also used.

DCS :

Desktop color separation. A format which creates five PostScript files, one file for each color and one low resolution master file.

DDCP (Direct Digital Color Proofing):

A prepress proofing method which creates color proofs without the need for film or plates by using only digital data.

DDES:

Digital Data Exchange Specifications.

Deboss:

To press an image into paper so it lies below the surface. Also called tool.

Deckle Edge:

Edge of paper left ragged as it comes from the papermaking machine instead of being cleanly cut. Also called feather edge.

Deflocculation:

To disperse pigment clusters into smaller units in an ink. Opposite of Flocculate.

De-Ionization:

The removal of ions from a solution by ion exchange.

Delta E:

Distance in the CIE L*a*b* color space between two colors. The delta E variable can be used to test color tolerances within a color-managed environment.

Densitometer:

An instrument used for reading the amount of light reflected by a surface or transmitted by an object. Densitometers are often used to measure the density of process-color inks on press. These density readings can then be used to calculate other values like dot gain and color difference. By measuring emulsion densities, Densitometers are also commonly used to analyze color characteristics of film.

Densitometer, Reflection:

An instrument used to measure color density on a printed sheet or reflective art.

Densitometer, Transmission:

An instrument for measuring transmission densities of color transparencies, film negatives and positives; for establishing density ranges; and for measuring reflective density of opaque copy.

Density:

(1) A measurement of the opacity of a transparent subject, or the weight of color of an opaque subject. (2) Weight per unit volume, usually expressed in grams per cubic centimeter or pounds per cubic foot. Density values are obtained by measuring the dot size. The larger the dot, the darker or denser the image.

Density Range:

Difference between the darkest and lightest areas of copy. Also called contrast ratio, copy range and tonal range.

Depolarization:

A decrease in the polarization of an electrode at a specified current density.

Desktop Publishing:

Technique of using a personal computer to design images and pages, and assemble type and graphics, then using a laser printer or imagesetter to output the assembled pages onto paper, film or printing plate. Abbreviated DTP.

Desorb:

To release absorbed molecules. Opposite of Adsorb.

Device dependent:

Describes a color space that can be defined only by using information on the color-rendering capabilities of a specific device. For example, the RGB color space must be generated by a monitor, a device that has specific capabilities and limitations for achieving its gamut of colors. In addition, all monitors have different capabilities and limitations, as do different scanners, printers, and printing presses.

Device independent:

A program or file format that can be used with two or more different computing devices and produce identical results. For example, a page saved in PostScript format should be printable on an HP LaserPrinter IV or on a Linotronic output. device.

Device Independent Colors:

Hues identified by wavelength or by their place in systems such as developed by CIE. A color that can be described and specified without regard to whether it is reproduced using ink, projected light, photographic chemistry or any other method.

Device Profile:

Device-specific color information that is a characterization of a device's color rendering and reproduction capabilities. Monitor profiles, scanner profiles, and printer profiles are utilized in a color management system such as Apple ColorSync to help the devices communicate color information with each other. Profiles are created by calibration and/or characterization method.

Diatomaceous Earth:

A substance consisting of the skeletons of billions of microscopic plankton, containing a high amount of silicon. A common paper filler, also used in ceramics, glazes and dynamite.

Diazo:

A light-sensitive coating used on printing plates.

Die:

Device for cutting, scoring, stamping, embossing and debossing.

Diecut:

The use of sharp steel rules to cut special shapes, boxes and containers, from printed sheets. Diecutting can be done on either flatbed or rotary presses. Rotary diecutting is usually inline with the printing.

Digital Camera:

A camera that transform visuals information (lightness and darkness) into pixels, then translate the pixel's level of light into a number (or, in the case of color, into three numbers: for the level of red, green and blue in the pixel). These digital images can then be manipulated pixel by pixel. They can also be compressed, stored and transmitted in more or less the same manner as other digital data.

Digital Dot:

Dot created by a computer and printed out by a laser printer or imagesetter. Digital dots are uniform in size, as compared to halftone dots that vary in size.

Digital Printing:

A system of printing that involves a direct link between printing presses and computers, bypassing the traditional route of making printing plates.

Digital Proof:

A proofing system that does not include the use of film. Data is sent to a printer and imaged directly onto a paper-based material. There are several limitations of a digital proof: 1) they do not use the film that will be used to produce plates, and thus are open to interpretation of the output device, 2) few of these devices print in the same dot pattern as is utilized in the printing process, and 3) the ink utilized in these printers is not representative of the inks used in the printing process, and can show a vast color range and density not attainable on a printing press.

Digitize:

To convert an image or signal into binary code. visual images are digitized by scanning them and assigning a binary code to the resulting vector or raster graphics data. Sounds are digitized by recording frequent "samples" of the analog wave, and translating that data into binary code.

D illuminants:

CIE standard illuminants that have a relative spectral power distribution representing the phases of daylight with      different correlated color temperature.

Diluent:

A liquid having no solvent power by itself. Used to thin an ink, not having a solvent action.

Direct Positive:

A positive obtained without the aid of an intermediate negative, e.g., Kodachromes(tm), Ektachromes(tm), etc.

Direct Transfer:

A method of transferring an image directly from film to metal, exposing a resist-coated cylinder directly through the film. This method was introduced in the 1950s as a replacement for carbon tissue.

Dispersing Agents:

Materials added in small amounts to facilitate dispersion of a pigment into a liquid medium; also, "Wetting Agents."

Dispersion:

A uniform distribution of solid particles in a vehicle.

Dissolving Pulp:

A grade of sulfite pulp used for cellulose films, cellophane and rayon

Dithering:

Simulating gray tones by altering the size, arrangement or shape of background dots.

DMAX:

The highest level of density on a film negative.

DMIN:

The lowest level of density on a film negative.

Doctor Blade:

Thin, flexible steel blade that passes over a gravure plate or cylinder, wiping off excess ink before an impression is made on paper. Can also refer to the entire assembly consisting of blade, doctor blade holder, and all necessary adjusting and loading devices.

Doctor Blade Holder:

Upper and lower clamp supports for doctor and back-up blades.

Doctor Blade Loading:

Applying blade pressure against the engraved cylinder.

Doctor Blade Streak:

Defect caused by the doctor blade not wiping clean, leaving stripes or lines of color on the web.

Dominant Wavelength:

(1.) The wavelength of light selected for measuring the brightness of papers. (2.) The single wavelength that represents the perceived color of any object, even though the effect may be a mix of red, green and blue light.

Dot:

An element of halftones. Using a loupe, you will see that printed pictures are made many dots.

Dot Gain:

An increase in the size of halftone dots that may occur as a result of errors or imperfections in any of the steps between screening an image and printing it onto paper. Common causes of mechanical dot gain are incorrect plate exposure, excessive tack or incorrect viscosity of printing ink, excessive ink film thickness, internal reflection of the ink, or too much pressure between the blanket roller and the impression cylinder.

Dots-per-inch:

Measure of resolution of input devices such as scanners, display devices such as monitors, and output devices such as laser printers, imagesetters and monitors. Abbreviated DPI. Also called dot pitch.

Double Bump:

To print a single image twice so it has two layers of ink.

Doughnut:

The appearance of a screen dot that has printed the circumference of the cell while not printing a complete dot.

Downtime:

Time the machine or equipment is not running.

DPI (Dots Per Inch):

A method of measuring the number of dots a printer can print per inch both horizontally and vertically to determine output device resolution and quality. A 600 dpi printer can print 360,000 (600 x 600) dots on one square inch of paper.

Drag-In:

The water or solution that adheres to objects as they are introduced into a plating bath.

Dragout:

(1.) Excessive ink around shadow areas of the image; usually associated with excessively deep etches, on a non-absorbent (coated) paper. (2.) The solution that adheres to objects as they are introduced into a plating bath. (3.) Build-up of pigments on edge of doctor blade that release and occasionally print on the web.

Drawdown:

Ink testing procedure, conducted by spreading ink on a substrate sample with a rod or K-coater, by hand or by mechanical means.

Drier:

A substance added to ink to hasten drying. They consist mainly of metallic salts, which exert a catalytic effect on the oxidation and polymerization of the vehicles employed.

Dropouts:

Very light areas in a halftone in which the halftone screen is eliminated to create pure whites.

Drop Shadow:

Created to give the appearance of a natural shadow and to better illustrate the effects of lighting. These shadows can be produced from the original image or they can be created by airbrush or vignette.

Dry Back:

The change in color or finish of an ink film as it dries.

Dry Color:

Pigment in dry or powder form.

Dry Cut:

A paper defect consisting of a long cut in the paper. This is a calendar cut occurring without wrinkling.

Dry Offset:

An indirect letterpress process in which the ink is transferred from a relief plate to a blanket and then to the stock. Similar to wet offset, but requires a coarser screen, normally 100 to 120 lines per inch. Produces printing quality higher than flexography but lower than wet offset.

Drying In:

Ink drying in cells.

Drying Oils:

Oils that process the property of hardening to a tough film by oxidation and polymerization.

Dull-Coated:

A moderately, glossy-coated publication stock, more reflective than matte, but less so than glossy.

Dummy

A rough layout of a printed piece showing position and finished size.

Dummy (or Dummy Cathode):

A cathode in a plating solution used for removal or decomposition of impurities.

Duotone:

A two-color halftone reproduction from a one-color photograph.

Duplicate Positive:

A high-quality positive made for the purposes of reproducing copy without using the original artwork. Duplicates all tone values of the original.

Duplicating Film:

Special films made for color and black and white uses.

Duplicate Transparency:

The reproduction of an original transparency made on transparency film.

Durometer:

A measure of rubber hardness usually made with Shore-A durometer gauge.

Dwell Time:

The time interval during which elements remain in contract or in a static position; pause.

Dye:

A colored substance, usually differing from a pigment in its solubility in various solvents.

Dye Transfer:

An opaque color print made from three dyed gelatin films, contact-printed over one another in register.

Dynamic Range:

An instrument's range of measurable values, from the lowest amount it can detect to the highest amount it can handle.

Dynamically Balanced:

Balanced on special equipment to run in perfect balance at high speed.