By Amber E. Watson
Digital print enables the production of quick, cost-effective, short run color output. To achieve new goals and quality expectations, digital printers require skill and advanced color management tools.
"Color management is still a bit of science and art," shares Roland Campa, product manager, EFI. "The idea is to have a color managed ‘handshake’ between all the different devices in the chain to provide an accurate representation of the required output from beginning to end." Frequent calibration of devices is required to provide accuracy across the board.
The ability to provide consistent and precise color is increasingly important in digital production. The competition wins if a provider cannot regulate color quality and meet evolving standards. Luckily, color management tools exist to help control the process.
Current Color Standards
Like much of the industry, Rick Hatmaker, worldwide technical, CHROMiX, Inc., is waiting on standards specific to digital. In the meantime, his company uses popular specifications like Specifications for Web Offset Publications (SWOP), General Requirements for Application in Commercial Offset Lithography (GRACoL), and G7 calibration, to help digital equipment work alongside other printing technologies.
"Although the standard was designed for offset, G7 is currently popular even for digital production in the U.S.," explains Campa. EFI Fiery XF 4.5.3 takes this trend into account, providing new verification tools for G7 Contract Proofm, G7 Greyscale Compliant, and G7 Compliant Proofing System. EFI’s linearization, profiling, and profile optimization wizards assist with passing verification for these categories.
Fujifilm North America Corporation also fully supports and participates in the ongoing efforts of organizations like IDEAlliance in developing certification processes, such as the Digital Press Certification, for the benefit of the industry.
Most digital printers target the GRACoL and ISO coated—Fogra 39 standards. This is relevant to bright white printing substrates. "From our experience, companies with digital presses are working toward SWOP standards," says Marc Welch, director of strategic accounts, GMG. "A number of label and packaging companies are starting to work toward color-consistent processes by adopting G7 standard specifications."
Agfa Graphics adopted GRACol and other standard for digital printing. "GRACoL isn’t a standard of color but a calibration to create consistent gray balance. That has translated to the wide format arena," explains Larry D’Amico, VP of digital imaging, Agfa Graphics.
For wide format applications, many utilize offset color models because the sign market has no real standards. Some digital print providers use SWOP as a standard for printing signs. D’Amico cautions that these digital devices feature larger color gamuts than a press, so by adhering to an offset guideline one is limited to a print standard, if it is a CMYK color space.
"Part of the problem is that many commercial campaigns have an offset component to them. In color management you have to take the lowest common denominator and that is the commercial print component. You don’t want to create a standard on a digital device that can’t be recreated in a commercial print space if you are trying to match a Pantone color," explains D’Amico.
George Adam, president, Techkon USA, says current color digital print standards are similar to existing ISO print standards, especially when the press seeks to produce offset quality prints. "These standards led to the development of new high-speed inkjet printheads; highly reliable media transport systems; high-end computer systems capable of processing the large volume of data captured from a digital press running at a speed of 1,000 feet per minute (fpm), and intelligent spectrophotometer technology that keeps up with the press to ensure every print is accurate and matches the color quality required by the customer," he adds.
Developing Standards and Tools
X-Rite Inc. developed its X-Rite Graphic Arts Standard (XRGA) for companies and professionals involved in digital production printing to adhere to ISO standards, ensuring that data sent or received from all links in the supply chain are reliable and repeatable. "In today’s global marketplace, it is imperative that companies are able to communicate precisely where a color resides in the space using digital data, regardless of the make or model instrument used," says James Luttrell, field marketing manager, X-Rite.
XRGA incorporates ISO-13655 with other best practices in color science methods to reduce measurement variation among instruments due to different calibration standards. This ensures handheld and benchtop colorimeters and spectrophotometers, formulation and quality assurance software packages, and equipment such as pressroom color scanners are measured and communicate using the same standards.
XRGA is an outgrowth of X-Rite’s integration of its own technology with that of GretagMacbeth, Pantone, and other entities that X-Rite has acquired. This standard aligns all X-Rite instrumentation to a single standard, regardless of the point or date of manufacture of a product. For instance, XRGA eliminates measurement variations for vendors that may be using both X-Rite and former GretagMacbeth instruments on the same project.
X-Rite’s Color Exchange Format (CxF) is a universal digital format that allows companies to communicate advanced color attributes that are not part of the standard ICC workflow. The format is an XML container that includes rich data to make color and appearance better defined so that color can be communicated accurately through CxF aware applications and solutions. CxF is available to developers to enhance solutions and provide high levels of color information to users.
New digital presses that incorporate inline color spectrophotometers capture 31-band spectral measurements while the press is running up to 1,000 fpm, explains Techkon’s Adam.
Other benefits include the ability to interface to a PC or tablet for remote viewing and reporting of color performance on press, giving the customer the ability to track the color quality of the job while it prints. Additionally, inline spectrophotometers enable automatic calibration of the press on a user-controlled schedule, which provides accurate color measurements for closed loop color control over long periods of time in an industrial, non climate-controlled environment.
"Applications made possible with an inline spectrophotometer embedded inside the digital press include quickly bringing ink color up to proper density quickly without operator intervention; checking the uniformity of the density across the entire width of the sheet; monitoring color density during a press run without stopping the press, and building an ICC profile on the fly when a paper roll is changed, the ink is replenishing, or after the press is serviced," adds Adam.
Color gamut differs between ink sets and with specific color spaces that work in conjunction with substrates and coating, presenting an ongoing challenge for print providers to produce a product that is as faithful to the original as possible.
As standards improve, so must a print shop’s capabilities. Access to and understanding of the latest color management tools helps print providers produce the highest quality product possible.
Part two of this series details several color management tools available by some of the top manufacturers