Have you noticed your printer colors don't always match what you see on the computer screen? Think it's your printer that's bad? Not necessarily. Understanding the basics of color science along with RGB vs. CMYK will help you identify color matching problems.
What is RGB?
RGB stands for Red, Green and Blue which are the primary colors within visible light. All of the colors that humans see are created from combinations of RGB light being transmitted to our eyes.
What is CMYK?
CMYK stands for Cyan, Magenta, Yellow and Black. By applying different combinations of CMYK toner or ink onto paper, we can remove (or subtract) some of the Red, Green and Blue light reflected from the paper's surface.
What about K?
Printers use CMY+K (also known as black). Rather than mix CMY together to produce black, printers utilize black ink or toner to ensure a pure black color. Also, using black toner and ink in place of CMY helps to reduce the amount of ink required, thereby saving money.
Although most printers use CMYK, each printer driver has unique color matching methods that renders color differently. They also have different color setting that the user can adjust. These settings create thousands of variations and outputs, thus explaining why your page will look different when printed on 2 different printers.
A note about paper...many people do not take into consideration that the same job printed on different types of papers (100% cotton, bright white, matte, glossy, etc.) may give you a different color output.
If you need exact matching, use Pantone®. Otherwise, you should just accept that the colors will be a bit different on each printed device. If your end goal is a great printed piece, do not worry about what you see on the screen. Print a sample, adjust colors in your program, and print another sample. Repeat until you achieve the desired output.