Digital Imaging Tutorial

6D. Technical Infrastructure:
DELIVERY

Key Concepts

introduction
networks
  concerns
  speed
  trends
monitors
  evaluation
  image quality
printers
  technologies
  evaluation

PRINTERS
As long as computers are bulky, display devices low resolution and hard on the eyes, battery technology in its infancy, and the communications infrastructure bound by cables, the desire to create printouts from digital images will endure. However, the costs of actually making high-resolution images available online, in formats that can be printed via a number of platforms and a range of printers, should not be underestimated. Before making promises to deliver print-quality images in a networked environment, verify that the technical infrastructure is up to the task, and consider the additional storage costs associated with online access.

PRINTER TECHNOLOGIES
Today, black and white printing is dominated by two technologies: Inkjet printers, which squirt liquid ink through tiny nozzles onto the paper, and laser printers, which use a light source to create charges on a photoconductive drum, allowing it to attract dry ink particles (toner) that fuse onto paper. Inkjet printers have become quite inexpensive, but are slower than lasers and generally not designed for high volume printing. High end production laser printers can produce well over 100 pages per minute at 600 dpi.

Both technologies have been adopted for color. Color inkjet printers come in 3- and 4-color models. Color lasers are much more expensive, both for initial purchase and for the cost of consumables. Color inkjets and lasers are both substantially slower than their black and white counterparts, color inkjets average about 5 pages per minute for text and 1 page per minute for full page graphics. Color lasers are faster, averaging 12 pages per minute for text, and 2 pages per minute for full page graphics.

Several other technologies are available for color printing. These include dye sublimation, solid ink, and thermal wax. Dye sublimation is especially significant in that it can produce true continuous tone color printouts, though it is extremely slow and requires special coated paper.

For larger scale color printing, Electronics for Imaging makes the Fiery line of print servers, which enable digital color photocopiers and digital presses to be networked to serve as high volume, high quality color printers. The resulting combination is called a copier-printer. Resolution is generally 400 dpi maximum, but is supported for whatever paper sizes the copier normally uses.