When looking at digital prints under a microscope, one can see a multitude of printed colors. However, for inkjet, dye sublimation and electrophotographic printers to recreate the world’s wide variety of colors on paper they must build them up from just a few starting hues. The minimum is three, which is what most dye sublimation printer’s use. This is the most basic possible color set: cyan, magenta, and yellow. The largest number is twelve in the most high end inkjet printers.
Printers also apply the colors in different ways. In dye sublimation, the translucent dyes are layered directly on top of each other during printing, making it impossible to ever see them separately (see below left). Inkjet and electrophotographic prints, however, use halftone imaging. In this process, colored dots are laid side-by-side (and sometimes overlapping) to create the illusion of different hues. For these, it is possible to see the individual colors and mixtures under magnification (see below right).
Unfortunately, the range of reproducible colors from any printer system can never truly match the entire range of colors in the world. What any given dye, ink, or toner set can actually produce is called its color gamut. Printer systems with a wide gamut can produce a large number of colors, while those with a narrow gamut produce fewer. Below are descriptions of the most common color sets, many of which can be seen under magnification.
Basic CMY
The smallest color set used in printing is cyan, magenta, and yellow. This is shortened to the acronym CMY. As stated above, this is the approach used by dye sublimation printers. It is also the approach used in traditional color photography.
Basic CMYK
Typical desktop/office inkjet and electrophotographic printers use CMYK as their color set, where K stands for Black. These systems produce a slightly broader range of colors, but most importantly produce text well, which is usually just black. Since dye sublimation is not intended for text printing, a true black isn’t necessary.
Photo Colors
Because inkjet and electrophotography are halftone systems, they must use dots to reproduce images. To create light image areas, the dots have to be smaller or further apart. In the lightest tones, this increased distance between dots degrades image quality. Manufacturers solved this by including light cyan and light magenta, which allows the dots to be larger or closer together. Note that yellow does not need a light version, as it is already very light. Some printer manufactures have also included greys to improve shading from light to dark.
Black-and-White Ink Sets
Along the same lines as above, some manufactures, most notably Cone Editions, have produced ink sets with a wide range of grey inks to make extremely high quality black-and-white inkjet prints.
Extended Color Sets
Even with light versions of cyan, magenta, and greys, the above ink sets still have limited color gamuts. To address this, some manufactures have added additional colors to their ink or toner sets to further improve image quality. These can include red, orange, green, blue, or violet. These are found only in the highest quality, and most expensive, printers.
Spot Colors
Finally, for commercial printing, some customers need very specific and accurate colors. This has led the digital press manufacturers to formulate unique colors for specific print jobs and applications. An example would be a corporate logo that needed to be an exact match to other company materials (i.e. a specific blue or a unique orange). These colors would only be used on those specific jobs and would not be included as a regular color in every print job.