D
definition
A subjective expression of detail clarity
degradé
A coloured halftone tint that gradually changes in strength and hue from one from one edge to the other. It may vary in hue in both directions depending on which process colour tint value changes. A vignette is only one colour that varies only in strength (brightness or lightness); one colour appears to fade away. Degradés are sometimes called graded tints; and are incorrectly called graduation.
delta E
Often written DE, a given amount of colour change. Delta refers to the Greek letter D that is used to indicate changing characteristics. In colorimetry, it is common to use a scale to indicate the change in a colour hue and strength. A reading can be taken by pushing a button on a colorimeter that automatically displays a computational value which represents the amount of colour change. Industry research has show that many customers will accept a variation in their printed products of six DE’s.
densitometer
An electronic, process control instrument that is used to measure the density (darkness) of visual images and colourants. Colour ink or dye densities are measured through their complimentary filter to indicate their relative strength. A densitometer should not used to indicate a point in a three-dimensional color space model. Density measurements are used to calibrate colour systems and to control colour processes.
density range
Tonal range, the maximum range of tones in an original or reproductions, calculate the mathematical difference between the maximum and the minimum density (the darkest and the lightest tones). For example, a transparency might have a 3.0 shadow density and a 0.25 highlight density. The lowest tone value, 0.25 is subtracted from the highest tone value, 3.0; the result is a 2.75 density range. A printed density range is 2.0 maximum or less.
density
The visual darkness of a material caused by its capability to absorb or reflect the light illuminating the material. Density is measured with a densitometer. Coloured materials are measured through their complimentary filters. Density differences are sometimes called grey levels. As density increases the amount or reflected or transmitted light is reduced. The amount of light absorbed is inversely proportional to the amount of light from or transmitted through the sample.
descender
The part of a lower case letters “g, j, p, q” and “y” that extends below the body of the letter or baseline.
descreening
The process of removing a halftone screen pattern from an image, either optically or with the use of the filters. A new screen can then be added.
desktop
- Refers to the size of a computer or a peripheral. A desktop device is small enough to use on a desk or a table as part as desktop publishing system.
- On the Macintosh graphic display, the area of the finder seen when the computer is first turned on, before any application is launched.
desktop publishing system
A standard platform computer, off-the-shelf software and an output device that are used to compose pages. The system components use a device-independent page description language - usually PostScript. A desktop publishing system is one type of electronic publishing system.
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