Sat, Aug

Mix and match

Mix and match

Do you have accurate colour matching across your wide-format printers? David Radtke, head of product management at colour specialist GMG, explains why it's easier than ever to get it right and make a difference to your business.

While accurate and consistent colour management has long been a fundamental consideration for other areas of print, the wide-format sector has lagged behind somewhat, but it seems it's waking up to the benefits it brings. A growing client awareness of colour management, and therefore an increased expectation of accurate colour reproduction regardless of output device, is no doubt one of the main reasons. Plus, the integration of colour management into the production workflow not only saves time, and potentially money, but can help you differentiate your business offering from competitors.

Perhaps the wide-format colour print industry has been slower to adopt colour management because of the perceived complexity and difficulty in reproducing and matching colour information when printed on a variety of commonly-used substrates.  Unlike with offset or gravure printing, or with smaller-format digital or inkjet devices, wide-format output is often onto more unusual print substrates so the challenge in ensuring consistent colour and density across such a wide span of media, ink formulations and industry standards has been reason enough for many to exclude integrated colour management from their workflow.  But, there is now a variety of software applications that, when used as part of a colour-managed workflow, can consistently and accurately reproduce colour, reference various output devices to a known starting-point, as well as reduce ink consumption on many machines.

Trial and error
We all know that to output consistent colour, many companies rely on image editing experts to 'tweak' a file's colours in an image-editing application, almost on a job-by-job basis, in order to output results that are 'good enough' to meet the client's expectation.  Such trial-and-error processes require considerable operator skill and consume company time and resources - often not reflected in the job price.

As the operator 'fixes' some colours in the image, something else in the image gets 'broken'. The whole approach is based on subjective visual assessment and the final result is often a compromise to deliver the 'least bad' result.  A similar situation exists when printing with different inks (solvent, aqueous, etc.), on different machines, with different Rips. Clearly, a more scientific-based approach that is measurable, repeatable and efficient in its use of time and materials is desirable.

A centralised colour management solution delivers better and more consistent results than individual printer-based systems, guaranteeing the same colour results on different output devices and printing conditions. For instance, GMG ColorServer, converts the incoming data based on colourimetric algorithms into the colour spaces of the different output devices. Next to the colour transformation a separation and re-separation is applied to guarantee optimum printability using the different ink systems. However, after the system is up and running, all you need to keep the system calibrated is a spectrophotometer and a measuring/calibration process that virtually anyone in the company can follow and accomplish.

The logistics of setting up the solution is relatively simple and begins with turning off the colour management on all device-specific Rips. Since the Rips will receive colour-managed files, they do not need to perform this function.

The next step is creating a reference or 'fingerprint' of the printer or press. A reference chart is printed and 'read' with a spectrophotometer. This allows GMG ColorServer to understand both what colours the printer can reproduce, as well as how it produces them. GMG ColorServer then takes the printer colour output, compares it to a preferred standard (such as GRACoL or ISO 12647-7, for example) and creates a so-called Device-Link to correlate the printer's colour capabilities to the colour standard. Printers with a larger colour gamut obviously support a better match to the colour standard or original colour being matched.

Wasting ink?
As a wide-format printer you may use a range of inks, both pigment and solvent-based.  The heightened concern over the environmental impact of solvent-based products means water-based inks have seen an increase in popularity - presenting an additional headache for many of you in terms of colour management. Applications like GMG InkOptimizer allow you to reduce the amount of chromatic ink used on a job, replacing it with black, yet retain all the image quality. The result is less ink application, lower ink consumption and a reduced burden on the environment.

GMG InkOptimizer users typically realise an ink-saving potential of between 10% and 15% - making a big difference when using the more expensive inks. The lower level of ink application also has other advantages. Greater shadow image definition is preserved and subsequent print operations, such as varnishing, can be performed sooner since the ink evaporates faster. The lower level of ink application also results in reduced energy requirements for IR and UV drying, as well as improved through-drying.

Proof positive
Another, often overlooked, area of wide-format colour management concerns proofing. Creating a proof using a wide-format printer is disruptive to the production process as we know, not to mention inefficient and costly. Using a different, smaller printer to show what a job will look like is highly desirable. But if you can't achieve accurate, consistent colour between different printers, you can't rely on the proof being an accurate simulation of the final product - the very reason that the proof has been created in the first place!  

If all of the printers used for proofs are linked and managed to the same standard using a common colour denominator (such as GMG ColorServer) a proof can be printed on any device (such as a smaller Epson or HP printer) to a known accuracy. Alternatively, the proofing device can be driven and colour-managed directly by a product such as GMG ColorProof. The software can automatically select the appropriate colour profile and calibration for a certain printer, including the appropriate paper. If the parameters do not match the actual settings, the job is automatically stopped for checking. As a result, possible sources of error such as incorrect printing settings, calibration files or colour profiles, are dramatically reduced.

The successful implementation of colour management for wide-format print is no longer as complex or as difficult as it once was, thanks to the availability of solutions from colour specialists. What's required is a corporate-wide initiative to move towards industry best practices that are only possible using scientific, measurement-based colour management. This moves the operator from a subjective, judgment-based approach to one where different operators can output the same file, on different machines, yet achieve identical results. What was once a time-consuming, difficult to teach and often inconsistent black art, has become an efficient, measurable and repeatable process. Both you and your customers will notice a difference.

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