According to a Pira report, RFID and printed electronics will have a big impact on the printing and publishing industries 
A little longer than 80 days perhaps, but UV-cure inkjet is circumnavigating the globe at its own accelerating pace. Printing and Publishing
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| Managing brand colours with colorimetric and spectral colour management systems |
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| Written by Hubert Scheir, Esko-Graphics | |
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All packaging supply chain partners from brand owners to press operators have been conditioned to think of colour management tools as profilers of print devices to generate acceptable contract proofs
Although that certainly is an important facet of colour management, there are many other factors that affect ultimate job quality on press. Packaging buyers need to be comfortable that the proof they approve actually matches the printed result - and therefore the actual product on the shelf. However, in packaging there are a lot of colour management issues that need to be resolved to ensure this level of predictability. In simple terms, a colour management system is expected to colour correct and match the press. Of course, a colour management system should be able to measure colour - both CMYK and spot colours. However, it's the level of spot colour handling that is the benchmark, particularly for packaging. Quite a few colour management systems claim to simulate spot colours. Yet, they rarely measure spot colours and never refer to colour databases. And, these systems are usually stand-alone solutions often linked to certain devices - they aren't fully integrated in a RIP and a workflow. Colorimetric and spectral colour management systems Colour management can be broken down to two approaches: colorimetric and spectral. Colorimetric colour management systems are based on the CIE L*a*b* colour space - an excellent method to specify colours on a very wide gamut and an exceptional means to verify colour accuracy. This measuring system relies on printed characterisation charts containing patches of different CMYK percentages and combinations. Colorimetric colour management systems describe the resulting effect of colours, but not the underlying mechanism of how they interact. This means the further the distances between the measured patches, the less accurate the profile. Spectral colour management systems determine the characteristic of inks. They rely on measuring the spectrum of inks individually and in overprint with other inks. Just as important, they measure the opacity of inks affecting the combination of inks on press. Using a database-driven mathematical model, the spectral colour management system provides the only practical solution for special colours. It is perfect for profiling special ink gradations and solids. By extrapolating the behaviour of colours to any set of inks, it describes the underlying mechanism that drives the final result. Some colour management systems combine both colorimetric and spectral colour management systems to provide the best of both worlds: the accuracy of CMYK along with a database of special colour profiles. Thus, the overprint between spot colours and CMYK are accurately predicted. Not just ICC The ICC colour profile specification is a popular buzzword and promises to provide a standard format. However, with different vendors, there are different colour matches and private tags. ICC offers very limited results for non-CMYK workflows and has no support for opacity levels or overprinting spot colours. Some systems support ICC profiles, but go beyond the capabilities of the ICC specifications. Look for a centralised, independent colour management system that will not rely on any proofer vendor. All colour tools should be used in any combination of process inks and special inks, and refer to a database for quality control. Multi-colour process printing Printing economics and print buyer requirements are convincing printers to consider multi-colour process printing (MCPP) rather than using spot colours. Typically, MCPP sets use a combination of CMYK and two or three additional colours such as orange, green and blue. MCPP is used to produce the same gamut as spot colours, so spot colours are no longer needed. MCPP delivers a number of advantages for the brand owner and converter alike. Because the same inks are on press most of the time, there is no need to clean stations for each new job. And, because different package designs can be printed at the same time, less product inventory is required - there is more freedom to return to press to print a specific package. With less spot colours, there is reduced ink inventory, while providing the designer adequate colour latitude to create appealing packaging. In short, there's a good balance between the wide colour gamut and printing economics. With MCPP colour sets, brand colours previously printed with spot colours now are created with multiple inks. Failing to print these colours accurately can affect brand identity and preclude consumers from buying the product. While printing with MCPP can save money, extra prepress costs are incurred to make jobs printable in MCPP. Trapping is more cumbersome, because pull-backs are much more intricate. What if black is not used: can this affect the readability of a barcode? How can one predict colours for new designs and images when special inks are combined - particularly in a separation? Can the new gamut of colours cover an image appropriately? How do two PANTONE® inks overprint? Proofing is more difficult with MCPP. Making use of the full available colour gamut on proofing devices is only one of the elements that will determine the success of proofing for MCPP. Systems that rely on colour charts developed specifically for MCPP purposes offer a single source for converting jobs to MCPP as well as for proofing. These profiles result in colour-accurate proofs, taking advantage of the full gamut of the proofing device. A multi-channel environment is crucial to successful MCPP. A good system provides efficiency and automation without compromise to flexibility and editability. It offers comprehensive solutions for MCPP implementation during every stage of the workflow. Other important features to consider for quality colour management Flexo highlight break Predicting flexo processes on proofing devices depends on the level of control under 10 per cent. Highlights and shadows must be visible to reveal severe colour shifts. Most systems rarely measure patches under 10 per cent, and virtually none measure 1 per cent and 2 per cent. Try to find a system that can refer to crucial input on highlight press behaviour by using the same dot gain curves. Relying on dot gain control and colour control results in very accurate colour and press-predicting proofs - screened and unscreened. Opaque and metallic inks Opaque inks and metallic colours have different opacity levels than CMYK inks. A colour management system should refer to spectral measurements that will assure a correct 'read' on overprints by measuring the level of opacity of inks. Ink order on press Ink order on press affects colour, so the colour engine must respect the ink order of a press run when proofing. A good colour management system can replicate the anticipated ink order and accurately demonstrate the change in colour if ink units are swapped on press. Dot gain Dot proof accuracy is critical, because both dot size and colour constantly interact. Many systems overlook the fact that not only the press has dot gain, but the digital proofer as well. Make sure your flexo-specific printing behaviour is adequately mirrored on both screened and unscreened inkjet proofs. This facilitates extremely precise reproduction in the highlights and shadows. Create once, output many The only reliable and consistent method to view colour is if a file is RIPped once for both the proof and printer. It is best if you can use the same engine that drives your platesetter for your proofs. Full colour gamut With an advanced colour management system, colour spaces are used optimally and intelligently to minimise out-of-gamut situations. Accurate traps Make sure that traps are visible, and the colour in the trapping area is accurate. For further information, please visit: www.esko-graphics.com |
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