IntroductionDigital pre-press workflows opened up an extensive new field in colour proofing – then promptly filled it with landmines. The main problem has been that, while it’s easy to produce basic proofs of page layouts for checking text-content and image positions – typically as black-&-white laser printouts – navigating colour-proofing has always demanded high expertise and even higher expense. But now, with easy-to-use desktop inkjet solutions becoming more affordable, contract-class PostScript pre-press proofing is within reach of every publisher and design team. Pre-press colour proofs must serve two purposes. First, they should present an accurate idea of how a page or spread will appear in terms of quality and general appearance. These are often required for signing-off by clients, creators, publishers and editors. Secondly, a colour proof must represent the final press output, not an idealized version; and this is where the trouble starts. Having a photo-quality inkjet to hand isn’t enough – unless you’re a photographer. For professional printing, your proofs must mimic the colour limitations of the process inks on the press, produce a reasonable impersonation of spot inks, and provide both creator and press-minder with a precise guide to real-world expectations. In the early days of the desktop publishing revolution, all this was left to repro houses and imagesetting bureaus, where experts would produce analogue cromalins and matchprints from film. With today’s design workflow fast removing the film stage – leading to computer-to-plate (CTP) and digital press output – analogue proofs are increasingly irrelevant. More to the point, if designers are preparing pages completely in-house in digital format for direct export to Acrobat PDF, proofing locally onto high-quality printers makes more sense. With the page remaining in digital format right up to the final stage, you can tease dot-gain, black component and other press-specific settings to enhance the predictability of your proofs. And with inkjet-based proofers now available from £1,000 upwards, bureaus and busy design studios can afford to produce more proofs faster for less money. RIP it up
Given that all pre-press revolves around PostScript, so should colour proofing. Relying on proprietary graphics interpreters to produce printouts adds another uncertain link the in the chain: if your pages are going to present a problem to the final PostScript output device (platemaker or digital press), you’ll want to know about it before it’s too late. So when you buy any colour printer sold as a proofer, it will be accompanied by some form of PostScript RIP. The RIP (Raster Image Processor) converts the raw print-data to complete PostScript page-information at the output device’s dot resolution and screen settings, then drives the printer to output the job. Some digital proofers include the PostScript RIP within the firmware of the unit itself, rather like office laser printers. Others put the RIP in an external unit where it can also act as an automated print server, freeing up both your Mac and the printer from unnecessary processing. In both cases, the PostScript RIP is just software – but being built into hardware kit, it’s known as a ‘hardware RIP’. Another method is to provide the RIP software as a Mac application that runs in the background on your machine, or, more likely, on a server, and uses the Mac’s processor to prepare the print jobs. This approach removes the need for additional processing hardware and ensures the RIP is easily upgradable and straightforward to maintain. On the other hand, it will tie-up the Mac it’s running on. Our round-up of four inkjet proofers covers each of these approaches to PostScript RIPs, so you can compare them like for like. We have also tested a couple of third-party software PostScript RIPs that have been designed to work with more-modest inkjet printers. Proof’s in the pudding
Pre-press professionals distinguish between accurate colour and ‘good enough’ colour when proofing. But in practice, ‘good enough’ isn’t. For this reason, no inkjet proofer is worth a bean unless its PostScript RIP can work with ICC device profiles and, of course, you have set up colour management on your Mac properly. At the same time, the print industry has gradually warmed to digital proofing. The result is that desktop inkjet output using PostScript RIPs can now be used as contract proofs – literally, accurate pre-press proofs which can be signed off in confidence by a client – rather than be written off as simply ‘good enough’. ICC profiles don’t appear from thin air: they are the result of careful calibration of your colour devices. Most scanners, cameras and printers come with generic ICC profiles from their manufacturers, but for sophisticated colour management you need to calibrate your actual kit. Setting up your monitor in ColorSync is just the tip of the iceberg. The cheapest way to do this is to buy colour profiling software and calibration targets, then rent a spectrophotometer, a colour-and-light sensitive device also confusingly known as a photospectrometer. With a bigger budget, you can hire a team of colour experts to come in and recalibrate your kit for you on a regular basis. Just remember that one of the key ICC profiles that you need is is the one for the final printing press. Most printing companies can provide you with these profiles, or are willing to run custom calibration tests. The latter, though, will be pricey.