What is the difference between RGB, CMYK and PMS colors?

Posted at July 3, 2009

When developing color for your print project or Web site, it’s important for you to know some of the ins and outs of these 3 color models.

RGB (Red, Green, Blue)
If you are reading this, you are reading an RGB display via your computer. RGB stands for Red, Green and Blue. The three colors that create every other tone of color that is visible on your screen. There is no black or white ‘color’. Neither is there yellow or purple. They are all combinations of red, green and blue. White is the sum of all three colors while black is the absence of all three colors. While each monitor is capable of displaying a wide range of colors, there are still inconsistencies between computers.

CMYK (Cyan, Magenta, Yellow, Black)
In four-color process (CMYK) printing, primary colors (Cyan, Magenta, Yellow, and Black) are mixed together to produce most of the colors that you see in normal magazines and color books. While there are six-color color spaces, these are much less common and are used for specific printing techniques.

CYMK is what the vast majority of commercial printers do, although there is a wide range of options. Images and artwork targeted for reproduction in a CMYK color space must be properly formulated to print correctly. If you’ve had the misfortune of trying to get an accurate print from an RGB image, you’ve just had a glimpse into the technical realm of 4CP (four color process) printing. To further confuse the issue, printers will often refer to their presses as 4, 5, or 6 color presses. While this makes sense to print designers, it is often lost on other customers. These numbers refer to the maximum numbers of colors that can be run in a single pass. For example, a tri-fold brochure could be designed to be printed in CMYK, plus a spot varnish, plus a metallic spot color. This ‘job’ is known as a six-color job since there are six colors of inks that will be run in a single pass.

PMS (Pantone Matching System)
Spot colors, also known as PMS colors, and officially as Pantone Matching System colors. Are specific color formulas that will reproduce accurately in print. Instead of simulating colors by combining primary colors, spot (PMS) colors are pre-mixed with existing and published color formulas. Because of this, you are nearly guaranteed that your PMS 186 from one printer will be matched by a PMS 186 from another printer. Better yet, often these PMS colors are pre-mixed by the ink factory, leaving even less to chance. “Spot” colors refer to the actual printing process by which they are applied.