CMYK • PMS • RGB • LAB: What does it all mean?

Understanding printing ink and color space can be confusing for even the most experienced graphic designers. Once each color space is understood, it becomes easy to focus. First, a few definitions:

  • CMYK represents the four process ink or toner colors: Cyan, Magenta, Yellow, blacK. This color space is often referred to as “process color” or “full color.” Printing equipment overprints various amounts of semi-transparent C-M-Y-K inks on paper. (cyan + yellow = greens, magenta + cyan = purples, cyan + magenta + yellow = browns, etc.). This printing technique is called “processing the color” and is the origin of the term: process color.
  • PMS is an abbreviation for the Pantone Matching System. It is a color identification system used to select and mix a single ink color. (similar to the way paint is purchased for a home redecorating project)
  • RGB stands for Red-Green-Blue light. It refers to additive light wave colors which, when combined, create pure “white” light. RGB color is used in monitor, TV, video and Website color spaces—not for printed materials.
  • LAB color is a 3-axis system of communicating color between different color delivery devices. Use LAB color profiles to match paint, plastic or fabric dye colors to an existing printed brochure. Graphic designers who create printing materials can ignore LAB color spaces altogether.

Selecting the Correct Color Space
Decide which color system you will be using before you start your layout. It has already been established that RGB and LAB are not used for graphics being printed on paper. That leaves two choices: CMYK or PMS color. Set up your document for one or the other in the color palette of InDesign. Then stay within that selected color space. The only time PMS and CMYK colors are used together is when a 5-color or 6-color job is being printed. (E.g.: CMYK + metallic silver ink = a 5-color job, CMYK + PMS 1495 orange + spot gloss varnish = a 6-color job).

Anytime photography or full-color illustrations are printed, CMYK color will be used. Due to higher efficiencies and a proliferation of digital imaging equipment, the cost for full-color printing has diminished over the past 20 years. Eighty-five percent of the commercial market is now printing with CMYK color. If you know your printed piece will be printed digitally, you must use CMYK color. Offset, screen, flexography and gravure presses allow designers to print using PMS or CMYK color.

If a piece is designed to print using only one ink color a PMS ink will be mixed and printed. Each individual PMS color has a number assigned to it with a mixing formula. Graphic designers use a Pantone “formula guide” book to select the exact color.

  • PMS inks are frequently referred to as “spot” colors (interchangeable terms)
  • Metallic inks are PMS colors with metal flake added to create a metallic sheen
  • Varnishes are inks with no pigment and are used for special effects

When a PMS mixed ink color is added to a CMYK printing order, it is referred to as a “fifth color.”

Most general commercial printers own offset and digital printing equipment. The offset method uses a “plate” to transfer inked images to the paper. Offset is more economical for large sheets and high quantities on textured papers. PMS, CMYK, metallic and varnishes can all be printed using offset presses.

Digital printing “direct-images” color to the paper using toner, dyes, or liquid inks. Digital printing is more economical for low quantities of small sheet-size items on non-exotic papers. CMYK is the only color space that can be printed using digital equipment.

One final word about RGB color
RGB color is not a color space used by printing companies—it’s used for back-lit monitors, video and Websites. Therefore, digital camera shots (which automatically produce RGB color files) should be converted to CMYK color before layout work begins.

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