Colors of Our World

A primer on the foundations of color communication.

By Terri McConnell

In the ideal world…the brand manager for a new line of lunch-box juices envisions his Citrus Cooler eight-pack carton: a brilliant, sun-ripened orange on a soft, butter-yellow field with the Florida Fun logo emblazoned in warm, metallic gold.

The designer, working from the manager's creative brief, mocks up the package using his favorite DTP programs, and e-mails the concept to the manager as a PDF file. The manager views the PDF on his PC monitor, and sends a note back: "Perfect! Let's see a prototype on Tuesday."

The designer forwards the PDF to a trade shop that renders the graphics on coated board stock. On Tuesday, the manager examines the prototype at arm's length, sets it on a shelf once or twice, and says, "Print it."

Less than a week later, the manager signs off a prepress proof. Just days after that, hundreds of thousands of Florida Fun cartons, with gold logos and brilliant sun-ripened oranges nestled on soft, butter-yellow fields, are shipping to grocery stores.

What's so far-fetched about that? All that's required is clear, concise, consistent communication of color. And that's the foundation for a host of industry initiatives and equipment enhancements focused on the issue of color management.

Speaking a common language

Just a pipe dream less than a decade ago, color management can today be accomplished in many different ways, depending on which one of an infinite number of printing workflows is being used. Says Dr. Richard Adams, a digital imaging and color reproduction specialist at the Graphic Arts Technical Foundation (GATF), "When the concept of color management was first commercialized, the technology was over-promised and over-sold. But today it exists; it's a practical reality. The problem now is getting people to understand it."

According to Adams, a pivotal point in color management's viability and wide-spread adoption was the release of Adobe Photoshop 5.0, which fully supports ICC profiling. The ICC, or International Color Consortium, was established in 1993 by eight graphic arts industry vendors led by Apple Computer. The ICC's purpose was to create and promote a standard for an open, cross-platform, vendor-neutral color management system architecture and components.

Today, there are dozens of members in the Consortium, and the ICC profile has become the unchallenged standard for digitally describing the precise attributes of color. (Visit www.color.org for more information about the ICC and the ICC profile.)

Beyond the ICC profile, there are a number of other industry standards important to color communication and primarily employed by software and hardware manufacturers. These are documents published by the American National Standards Institute, Committee for Graphic Arts Technical Standards (ANSI CGATS), such as CGATS.4-1993, which details the terminology, equations, image elements, and procedures for measuring reflection densito-metry.

In addition to standards, the industry has adopted several universal printing specifications which are helping to perpetuate color consistency. These specifications were written by committees of printers and suppliers based on experimental press runs to determine specifications that can be generally met by the average printer

• SWOP, The Specifications for Web Offset Publications

• GRACoL, The General Requirements for Applications in Commercial Offset Lithography

• SNAP, The Specifications for Non-Heatset Advertising Printing, and

• PROP, Prepress Requirements for Offset Packaging.

SWOP, by far the most widely accepted and mature specification, is currently in its eighth edition. It includes specifications for separation films; inks, substrates, and dot gain for proofs; and inks, substrates, density, and dot gain for production printing. The SWOP spec has recently been expanded to include discussions of best practices for print production.

PROP, the only packaging-specific specification, was originally intended to represent ideal conditions for printing on carton substrates including solid bleached sulfate, recycled board, and polycoated boards. Unfortunately, the PROP committee has disbanded and development on this spec is discontinued. Flexography's F.I.R.S.T. represents the most active specification initiative targeted directly at packaging applications and substrates (see packagePRINTING, January 2000).

Lest you be confused by all this talk of specifications and standards (I was), Dr. Adams offers the following analogy: "A standard is like the atomic clock in Boulder. All the airlines can synchronize their schedules precisely by it, but it doesn't tell us what to do if we're late. A specification, on the other hand, tells us that we are required to check in at the gate an hour before departure. And best practices recommendations might suggest that we take a specific alternate route to the airport to avoid rush hour traffic."

Characterization and calibration

Without the above standards, specifications, and even best practices, our ability to communicate color consistently throughout the entire printing process would be hit or miss at best.

The ICC standard guides us as we move from one color "space" to another; for example as we move a photograph from its scanned, larger-gamut RGB color space to the more limiting CMYK printing color space.

Proofing device vendors like DuPont have invested heavily in building ICC-compliance into their output devices. Beyond that, says Mark Mazur, a digital prepress consultant with Cyrel® Packaging Graphic Products, "The number one criteria for any proofing system is consistency. Not only from any specific device, but from device to device."

Mazur explains the proofing process was originally developed to show a customer what his product would look like once it was printed. However, somewhere along the line, the proof itself became the target.

"With today's sophisticated proofers and color management tools, we have come full circle," says Mazur. "We can, to varying degrees depending on the performance of the device, actually simulate the printing result on the proof."

Calibration tools allow printers to make sure the device produces the same result time after time. According to Mazur, DuPont has incorporated the DTP41 strip-reading spectrophotometer from X-Rite into its proofing solutions. The DTP41 reads a test target of 288 color points, and, based on those results, the proofer can be adjusted "back to norm."

Another, third aspect of effective color proofing is the availability of a suite of tools to adjust color for specific preferences. While the internal mathematical color descriptions are objective, overlay color management programs allow you to make subjective color decisions. For example, to show the customer a proof with a greener green, or a photo printed with a warm red separation instead of a magenta separation.

Effective color management can represent a huge step change in the way quality expectations are established and realized within the printing industry. Clearly, systems that adhere to the standards and specifications mentioned here will have greater flexibility and value.