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.