Appendix E: Glossary 337
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.
ROM: Read Only Memory: Memory storage that,
having been programmed once, retains its data without
requiring electrical power. EPROM
Run Length Encoding (RLE): A technique used in
many image compression methods, including JPEG.
Repeating values are not stored separately but with a
counter to indicate how many times the value occurs in
succession – the length of the “run”.
Scaling: Adaptation of an image to a desired size.
SCSI: Small Computers System Interface. SCSI was
long preferred as the hard drive interface for some
high-performance PCs because of its high data rate. Up
to eight SCSI devices can be connected to a computer
at the same time.
SECAM: “Séquentiel Couleur à Mémoire”, a color TV
transmission system used in France and Eastern Europe.
Like PAL, SECAM video has 625 lines per frame and
50 image fields per second. NTSC, PAL
Serial port: Data transmitted via a serial port is
processed one bit at a time; that is, “serially” – one
after another. The transmission rate is much slower
than that of a parallel port, where parallel data lines
allow multiple bits to be sent simultaneously. Serial
ports are named “COMn”, where n is a number (e.g.
“COM2”). Parallel port
SIF: Standard Image Format. An MPEG-1 format
specifying a resolution of 352 x 288 under PAL and
352 x 240 under NTSC. MPEG, QSIF
