A dye-sublimation printer (or dye-sub printer) is a computer printer which employs a printing process that uses heat to transfer dye onto materials such as a plastic, card, paper, or fabric. The sublimation name was first applied because the dye was considered to make the transition between the solid and gas states without going through a liquid stage. This understanding of the process was later shown to be incorrect. Since then, the process is sometimes known as dye-diffusion, though this has not eliminated the original name. Many consumer and professional dye-sublimation printers are designed and used for producing photographic prints, ID cards, and so on.
These are not to be confused with dye sublimation heat transfer imprinting printers, which use special inks to create transfers designed to be imprinted on textiles, and in which the dyes do indeed sublimate.
Some dye-sublimation printers use CMYO (Cyan Magenta Yellow Overcoating) colors, which differs from the more recognized CMYK colors in that the black is eliminated in favour of a clear overcoating. This overcoating (which has numerous names depending on the manufacturer) is also stored on the ribbon and is effectively a thin layer which protects the print from discoloration from UV light and the air, while also rendering the print water-resistant.
For ID card printing, text and bar codes are necessary, and they are printed by means of an additional black panel on the (YMCKO) ribbon. This extra panel works by thermal transfer printing instead of dye diffusion: a whole layer, instead of just some of the dye in the layer, transfers from the ribbon to the substrate at the pixels defined by the thermal head. This overall process is then sometimes called D2T2 (Dye Diffusion Thermal Transfer).