How to Convert Pantone to CMYKby Elizabeth Mott
Color reference systems provide reliable, repeatable standards that define the appearance of sets of colors and the ink mixtures that print them. Among these standards, the Pantone Matching System establishes reproduction formulas for inks that produce solid colors and process-color mixtures of CMYK inks. When you convert Pantone spot colors to process-color equivalents, your translation should produce formulas that provide a cohesive appearance between the two printing methods.
Spot Vs. Process Inks
When you design a brochure, magazine or business card in process color, the printing press produces all the tones and shades in your project through mixtures of cyan, magenta, yellow and black inks. A Pantone spot color loads into the press as a premixed ink that reproduces only that specific shade or tints at percentages of its full-strength color. On a profiled, calibrated monitor within a color-managed workflow, what you see onscreen can come close to replicating the appearance of spot colors, but only printed output can reproduce them perfectly. If you design a project using 12 Pantone spot colors, printing it requires 12 separate inks -- which most printing presses and budgets can't accommodate -- or a conversion from spot to process color.
Pantone provides several sets of mixing formulas for each of the thousands of shades it creates. The first specifies the recipe for mixing Pantone's building-block inks to produce a spot color. Printing companies can buy premixed spot colors or formulate their own ink mixtures following the official formula for each shade. Pantone's second mixing formula defines a combination of process-color primary inks that comes close to reproducing a corresponding spot color. In addition to these printing specs, Pantone also specifies how each ink should appear onscreen in the design, illustration and page-layout applications that support its colors through licensed digital libraries.
You can make conversions between spot and process color in two ways. The simplest invokes Pantone's spot-to-process conversion formulas through a few clicks in the color setup dialog boxes within a piece of graphic arts software that incorporates these colors in its digital palettes and selectors. If you own copies of Pantone's spot and process color selector guides -- printed swatch books that show you how each color should look on papers with varying types of surfaces -- you can browse through both books side by side, select the best match based on your review and substitute the process color in your digital documents. The result still relies on an official Pantone formula that a commercial printer can reproduce reliably from reference standards.
Not all spot colors reproduce well within process color's gamut or range of shades. Bright cobalt blues and saturated shades of orange constitute two notable exceptions that lose much of their vividness in the translation from spot to process. If you must print your design in process color as well as in spot-color inks, plan your design around colors that offer suitable process substitutions and preview all the colors you use in swatch books that show you what to expect on paper.
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