55
Glossary
Term Description
Distortion A usually undesirable variation from an intended output caused by the characteristics of a particular
device.
Dithering Method of displaying intermediate colours that don’t exist in a limited palette by using a pattern of
small dots out of that palette.
DLP
DLP
(Digital Light Processing) is a commercial name for a display technology from Texas Instruments®
(TI). The technology inside is often referred to as DMD (Digital Micro-Mirrors). It consists of an array of
mirrors where each mirror represents a pixel element. For example, a high-definition DLP
projector
or rear projector with 1920 x 1080 pixel resolution would have over 2 million tiny mirrors. Each mirror
is attached to an electronically driven hinge that controls the amount of coloured light that is reflected
from the mirror into the projection lens and onto a screen. Projection systems using DLP
technology
use 1 to 3 DMD devices.
DMD Digital Micromirror Device. Name of the actual imaging chip used in a Texas Instruments DLP
projection systems.
DNR Digital Noise Reduction. A system that reduces picture noise by comparing previous frames to the
present and smoothing out what appears to be noise to the algorithm. Helps reduce flickering in still
parts of a video image.
Document
Camera
A document camera can be attached to any projector; however, there are projectors that integrate
these features either as a camera on an arm that is attached to the projector or a document scanner
that is built into the body of the projector.
Dolby Digital A lossy compression system to deliver sound on DVDs, ATSC and DBS broadcasts in up to 5.1
channels. Also called AC-3. See AC-3.
Dolby EX Backwards compatible system to add a sixth channel used for the middle rear playback to Dolby
Digital (AC-3) making it 6.1 or 7.1 sound. 7.1 sound uses an additional center rear speaker playing back
a duplicate track. Needs a Dolby EX decoder. See AC-3.
Dolby Pro Logic An analog 4 channel surround sound system with left, right, center channels and a mono rear
channel, typically duplicated across 2 speakers. Rear channel is limited to 7KHz and system stores
all channels in a matrix recording on 2 discrete analog channels. Has difficulty playing back non-
encoded material at full fidelity.
Dolby Pro Logic
II
Updated version of Pro Logic. Offers better performance with playing back non-encoded sources
over a surround sound system with full spatial cues and fidelity.
Downconvert To convert a higher resolution signal to a lower resolution. For example, 720p to 480p.
DTV Digital Television. A system that uses digital signals instead of analog including the ATSC standards,
DBS and digital cable.
Dual Lamp A Dual Lamp projector has two lamps where one lamp either serves as an automatic backup to
the other lamp or is preprogrammed to switch at specific intervals. The benefit of this type of lamp
system is it significantly reduces the probability of lamp failure during use.
DVI Digital Visual Interface. DVI is a standard that defines the digital interface between digital devices
such as projectors, flatscreens and personal computers. For devices that support DVI, a digital-to-
digital connection can be made that eliminates the conversion to analog and thereby delivers an
unblemished image.
It can also carry an analog signal and comes as DVI-I (integrated - analog and digital), DVI-D (digital
only) and DVI-A (analog only). Dual link DVI connections add additional resolution capabilities.
Specifications on DVI are available at www.ddwg.org.
Dynamic Range The ratio between the highest and lowest levels a device can perform. For a video device it is a
measure of contrast ratio. For an audio device it is usually stated in dB.
Glossary
To Next Page
Loading...
Need help?
General
