Open
Prepress Interface (OPI) -
Developed by Aldus Corporation to manage image files used in page layout and
illustration applications.
Utilizes high and low resolution versions
of images. Low resolution for placement in pages and high for final output.
OPI commands inserted into PostScript
to keep track of different versions of images.
Often makes use of higher bandwidth
interfaces between server, scanner and output devices.
Remote
File Transfer - Often necessary to transfer
images and pages to customers or suppliers.
Modems (Analog connections) now offer
data rates up to 56 Kbps. Compression can sometimes more than double this
for some kinds of data.
Digital connections such as ISDN can
make use of multiplexed 64 Kbps to achieve thruput up to 155 mbps.
In order to be transferred efficiently,
files need to be compressed. Compression can be done during the transfer
by data compression modems or before transfer.
Files need to be compressed prior
to transfer because not all data links provide compression.
Compression algorithms are either
lossy or lossless.