Printer calibration is the process of making the printed image match the image shown on a computer display. Only those people printing large photographs or detailed graphics probably need to regularly use manual calibration, as others can make use of a printer's automatic calibration settings. Think of calibrating a printer as achieving what-you-see-is-what-you-get (WYSISYG) printing.
A computer display and a printer don't always produce the same image for a few different reasons. First, print ink dots naturally overlap a little bit on the paper, while the pixels on displays do not overlap. Second, printers commonly create images slightly darker than computer displays. Third, printers mix four pigments to create colors (cyan, magenta, yellow, and black), while displays contain pixels of three colors (red, green, and blue). Finally, different types of paper will affect the final printed image, whereas displays don't have such issues.
With printer calibration, the software that controls the printer, also called the printer driver, can adjust the printer's various settings to help it match the display. For example, some printer drivers will print a test page containing several images, also called a calibration sheet, that can be compared to the display to reveal any adjustments that need to be made. Sometimes, the printer calibration test can be found with a software suite included with the printer, rather than with the printer driver. With some printers, the calibration test is called a diagnostic page or a self-test page. Be certain to have downloaded the latest versions of the printer's software before beginning a calibration.
Some new printers are able to perform minor corrections automatically. For example, some printers perform the calibration techniques when undergoing a print-head cleaning procedure. To allow the printer calibration to occur successfully under automatic mode, it's important to have the proper paper in the printer, as recommended by the manufacturer. An empty ink cartridge will probably cause calibration errors in automatic mode. Finally, if the printer continually produces error messages and poor results during its automatic calibration sequence, try resetting the printer, as directed by the manufacturer.
For those who are interested in calibrating a printer to create large, accurate photos, do not attempt printer calibration until calibrating the computer display, too. Be certain to avoid reflections on the display and to limit room lighting as much as possible when attempting display calibration. Search the Internet for "monitor calibration image," "display calibration image," and "printer calibration image" to find methods and samples for performing the tests manually.