Glossary 531GlossaryWeb Design in a Nutshell, eMatter Editionkey frames
In video, master frames placed throughout a video against which the
following frames are compared (for use with temporal, or interframe,
compression).
Linux
A version of Unix designed to run on PCs.
lossy compression
A method for reducing file size in which some data (usually indiscernable to
human perception) is deleted in order to achieve a higher compression rate.
lossless compression
A method for reducing the size of a file without loss of data; in lossless
compression, redundant information is removed.
LZW compression
Short for Lempel-Zev-Welch, the names of the inventors. A lossless compres-
sion scheme that takes advantage of repetition in data streams (such as a row
of pixels of identical color). It is the compression scheme used by graphic
files in the GIF format.
MIDI
Musical Instrument Digital Interface. This audio format uses mathematical
commands to describe the pitch and endurance of notes that are “played” by
available digital instrument sounds.
MIME types
Multimedia Internet Mail Extensions. A protocol that defines a number of
content types and subtypes, and allow programs like web browsers, news-
readers, and email clients to recognize different kinds of files and deal with
them appropriately. A MIME type specifies what media a file is, such as an
image, audio, or video, and a subtype identifies the precise file format.
MPEG
A family of multimedia standards created by the Motion Picture Experts
Group, commonly used to refer to audio and video files saved using one of
the MPEG compression schemes.
palette
A table in an 8-bit indexed color file (such as GIF) that provides color infor-
mation for the pixels in the image. See alsoCLUT.
PDF
Portable Document Format; a file format developed by Adobe Systems used
for capturing formatted page layouts for distribution. PDF documents, when
viewed with the required Adobe Acrobat Reader, will appear exactly as they
were intended.
PNG
Portable Network Format; a versatile graphics file format that features support
for both 8-bit (PNG8) indexed images and 24-bit images (PNG24). PNGs also
feature variable transparency levels, automatic color correction controls, and a
lossless, yet highly efficient, compression scheme.