Dedicated photo printers differ from all-purpose printers as they are designed to print photos only, as opposed to text or graphics documents in addition to photos. They are generally compact in size and lightweight, and some models even feature batteries that allow you to print without the need for an outlet. Most photo printers, including dye-sublimation (or dye-sub) printers, are built around a thermal dye engine, though there are a few that feature inkjet technology.
For many years, dye-sublimation printers were specialist devices used in demanding graphic arts and photographic applications. The advent of digital photography led to the entry of this technology into the mainstream, forming the basis of many of the standalone, portable photo printers that surfaced in the second half of the 1990s.
The term "dye" in the name refers to the solid dyes that were used in the process instead of inks or toner. "Sublimation" is the scientific term for a process where solids (in this case, dyes) are converted into their gaseous form without going through an intervening liquid phase.
The printing process employed by true dye-sublimation printers differs from that of inkjets. Instead of spraying tiny jets of ink onto a page as inkjet printers do, dye-sublimation printers apply a dye from a plastic film. A three-pass system (featuring solid dyes in tape form on either a ribbon or a roll) layers cyan, magenta, yellow, and black dyes on top of one another. The print head on a dye-sub printer uses tiny heaters to vaporizer the dye, which permeates the glossy surface of the paper. A clear coat is added to protect the print against ultraviolet light. Although this method is capable of producing excellent results, it is far from economical. Even if a particular image does not need any one of the pigments, that ribbon segment is still consumed.
This is the reason it is common for dye-sub printer compatible paper packs to contain a transfer film capable of producing the same number of prints. In addition, dye sublimation inks need a paper that allows the ink to remain on the surface of the paper. Nowadays, a number of inkjet printers on the market are capable of deploying dye-sublimation techniques. The cartridges in such printers spray the ink, covering the page one strip at a time.