| D.J.H. |
German
National Standard. |
| D.P.I. |
Dots
per inch. A measure of the detail of a print. "Apparent d.p.i."
refers to the fact that the eye perceives an image as having greater
detail than in does in physical reality. |
| D65 |
The
CIE Standard Illuminant that represents a colour temperature of
6504_K. This is the colour temperature that is most widely used
in graphic arts industry viewing booths. See Kelvin (K). |
| Daylight
Illuminants |
CIE
Series of 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. |
| Decal |
Small
graphics, long or short-term, printed on adhesive-coated vinyls
or transfer materials. |
| Decalomania
(Decals) |
See
"Transfers". (In the USA the term "Decals" also
embraces printed self-adhesive plastics). |
| Degreasing |
Removing
dirt and oils from the stretched screen before applying the stencil
to insure adhesion to the screen surface. |
| Densitometer |
An
instrument that measures transmitted or reflected light. It will
indicate, in density units or percentage dot, the percentage of
a given area that is covered by halftone dots. This instrument is
used to ensure consistency and process control.
|
| Density |
The
degree of opacity of an image. A measure of reflectance or transmittance
equal to log10 (1/reflectance) of log10 or (1/transmittance). The
ability of a material to absorb light; the darker it is, the higher
the density. Density measurements of solid ink patches are used to
control ink on paper. |
| Depth
Of Field |
The
distance in front of, and behind, the subject that will be acceptably
sharp. This distance will increase as the lens aperture is reduced. |
| Diazo |
A
photosensitive chemical added to emulsion used in making screens
(stencil). |
| Dichroic
Filter |
A
glass plate coated with a number of thin layers of material that
will reflect all but one very specific colour. Also called dichroic
mirror. |
| Die-Cut |
Cutting
of material to a specific shape using dies. |
| Diffuser |
The
translucent-white sheet that evens out the light coming from the
lamps in an optical system. |
| Digital |
Image
and line data that has been translated into numerical values for
manipulation and reproduction. |
| Digital
Camera |
Portable
optical recorder that captures images on an internal memory chip,
removable PC cards, or other digital media. Images can be transferred
electronically to a computer for manipulation, e-mailing or website
creation. |
| Digital
Colour Printing |
One
of several non-impact technologies where the image is formed by
a computer controlled printer. (Generally accepted to include: electrostatic,
ink jet, laser photo, and thermal transfer.) |
| Digital
Halftone |
The
process of obtaining various tones by breaking up the image into
a graduated series of dots. The dots repeat in a regular pattern,
creating the illusion of continuous tone. The digital printing process
is controlled by the size and shape of dots. |
| Digital
Imaging |
The
process of image capture, manipulation and final image form, accomplished
by electronic systems. |
| Digital
Internegatives |
Internegs
that are produced by digitally scanning the original transparency
to create a digital file, then imaging the digital data using a
film recorder to record the image onto a negative film stock. |
| Digital
Printer |
Any
printing device that is capable of translating digital data into
hardcopy output. |
| Digital
Signal Processors (DSP) |
Microprocessor
chips specially designed to convert, modify and manipulate streams
of digitised signals in real time. These chips allow for faster
telephony, faxing, and audio and video capture and editing. |
| Digital
Signature |
A
means of authenticating electronic documents. A digital signature
is actually a special kind of encrypted message needed for electronic
commerce. |
| Digitise |
The
process of converting analogue data to digital information. |
| Diluent |
A
volatile liquid which, while not necessarily a solvent for the non-volatile
constituents of an ink, may yet be used in conjunction with the
true solvent without causing precipitation. |
| Dimensional
Stability |
The
ability to resist dimensional change; i.e. the amount of shrinkage
or expansion. |
| Direct
Emulsion |
A
liquid photo-polymer emulsion used as a screen printing stencil
which is coated onto a stretched screen, dried, exposed through
a film positive to actinic and developed. |
| Direct
Illumination |
Signs
lit from the outside with floods, spots, etc. |
| Direct
Projection |
A
method of exposing a screen printing stencil that uses a small format
(typically A4) photopositive to produce a large image (typically
8 feet by 4 feet) |
| Direct-to-Screen
Printing |
Imaging
techniques that allow for the elimination of film separations from
the printing process. These systems utilise a computer controlled
system employing digital printing heads to "write" digital
data to a coated screen that is then mounted on the press. |
| Dispersion |
The
breaking up of a particle aggregate into separate particles without
changing the particle size. |
| D-MAX |
Highest
level of density. |
| D-MIN |
Lowest
level of density. |
| Doctor
Blade |
Rigid
or flexible steel blade used to remove excess from printing Plate.
Also called blade, wiper, squeegee. |
| Dot |
Dots
make up an image in colour separations or halftones. Halftone dots
will have a fixed density but have variable size (amplitude modulation). |
| Dot
Area |
Percentage
of paper covered by ink dots of a given colour. See Apparent Dot
Area. |
| Dot
Gain |
The
phenomenon that occurs when ink expands its coverage during printing
onto a substrate; often caused by abnormal or excessive absorption
by the substrate or low viscosity inks. |
| Dot
Pitch |
The
distance between the dots on a computer monitor, typically 0.24
to 0.38 mm. The closer the dots the sharper the image on the monitor. |
| Dots
Per Inch (DPI) |
A linear measurement of resolution used for scanning and printing.
Generally, more dots per inch mean a higher resolution, a greater
amount of visible detail in the image, and a larger file size. |
| DPI
(or PPI) Dots Per Inch/Pixels Per Inch |
The
resolution of an image or how many pixels are defined in the boundary
of an inch. The more correct term is pixels per inch, however dots
per inch is often used instead. This more correct in the case of
electronic files. |
| Drop-Shade
Or Drop-Shadow |
The
shadowing effect on letters, to simulate light being cast at an
angle. |
| Drum
Scanner |
A
type of optical scanner where the reflective or transmissive art
is mounted to a rotating drum. As the drum spins, light from the
image enters a lens allowing the image to be recorded in a series
of fine lines. |
| Dryer |
A
machine for drying wet prints. |
| DTP |
Acronym
for desktop publishing, including typesetting, image handling and
page composition. |
| Dual
Pack |
See
"Two Pack". |
| Duotone |
A
monochromatic printed image created by two overlapping halftone
screens of different colours; generally created from a black and
white photographic original in order to add additional tonal range,
or to create a tinted or coloured appearance. |
| Duplex |
To
print on both sides of a single page. |
| Durability |
A
relative term used to describe the functional life span of a material
or ink typically compared to a control. |
| DVD
(Digital Versatile Disc) |
A
technology similar to Compact Disc, but far superior in its storage
capacity. A DVD can contain about 4.7 GB of data in its single-sided,
single-density version, and 18 GB or more in a double-sided, double-density
version. |
| Dye
Sublimation |
An
imaging process that vaporises colorant with heat and pressure,
and deposits it on to a substrate in order to simulate a continuous
tone image. |
| Dyes
and Dyestuffs |
Organic
colouring substances. Pigment dyestuffs are virtually insoluble
in water and in the usual ink and varnish vehicles. Some dyes are
soluble in water and organic solvent and are classed according to
their solubilities. A soluble colorant; as opposed to pigment, which
is insoluble. |
| Dynamic
Range |
The
measurable difference between the brightest highlight and the darkest
value. |
