Appendix E: Glossary 427
Port: Electrical transfer point for the transmission of
audio, video, control or other data between two
devices. Serial port, Parallel port
Primary colors: The colors that are the basis of the
RGB color model: red, green, and blue. It is possible to
create most other colors on a computer screen by
varying the blend of these primaries.
QSIF: Quarter Standard Image Format. An MPEG-1
format specifying a resolution of 176 x 144 under PAL
and 176 x 120 under NTSC. MPEG, SIF
Quantization: One part of the JPEG image data
compression strategy. Relevant details are represented
precisely, while details that are less relevant for the
human eye are represented with less precision.
Raster: The area of a video display that is covered by
sweeping the electron beam of the display in a series of
horizontal lines from upper left to lower right (from the
viewer’s perspective).
Redundancy: This trait of images is exploited by
compression algorithms. Superfluous information can
be eliminated during compression and restored without
loss during decompression.
Resolution: The number of pixels that can be displayed
on the monitor horizontally and vertically. The higher
the resolution, the more details can be displayed.
Pixel
RGB: Red, Green and Blue: the primary colors in
additive color mixing. RGB designates the method
used in computer technology of encoding image infor-
mation in pixels, each containing some combination of
the three primaries.
