In short, printers and monitors produce colors in different ways.
Monitors use the RGB
(red, green, blue) color model, which usually supports a wider spectrum of colors. Printers use the CMYK
(cyan, magenta, yellow, black) color model, which can reproduce most—but not all—of the colors in the RGB color model
. Depending on the equipment used, CMYK generally matches 85–90% of the colors in the RGB model.
When a color is selected from the RGB model that is out of the range of the CMYK model
, the application chooses what it thinks is the closest color that will match. Programs like Adobe Photoshop will allow you to choose which color will be replaced. Others may not.