01.04.09
RIP Software Review
The proof of the pudding is definitely in the print when it comes to RIP applications. Place a print produced by any standard printer driver (and custom profile if you wish) against a successfully optimised and profiled RIP (raster image processor) print and stand back and look at the glorious differences a decent RIP can make. You’ll get better colour accuracy, better tonal gradation, a potentially wider colour gamut, denser blacks and reduced issues of metameric shift under differing lighting conditions. And that’s not to mention the other advantages that a good RIP, successfully installed, can bring to photographers: reduced ink usage, faster printing times and workflow and paper savings.
A further benefit to using RIP software is the ability of some applications to produce certified proofs of your images for a particular output press. Being able to deliver files in CMYK, along with a certified proof, lets your printer know that the wonderful colours you’ve managed to produce can be matched via an offset press. This way the printer has to take its share of responsibility for any defects in the final product. Viewed in a positive light, it means that you can produce the best possible CMYK conversion of your image and sleep soundly knowing it should reproduce that well in magazine, brochure, catalogue or any other printed medium.
RIP software delivers quality and ink-saving benefits through the ability to calibrate an inkjet printer prior to the profiling process. The calibration is performed in two ways, the first of which comprises ink limiting. This involves adjusting the actual amount of ink laid down in high inking areas, such as shadows and dark colours, and should ideally be adjusted for each individual ink tank. Each ink will have an optimum maximum delivered amount for a particular paper at which no more gains are made in terms of saturation – going beyond these maximums not only wastes ink, but can actually reduce density and cause problems with bleeding, blurriness and even
colour shift.
The second part of the process is linearisation. This ensures that the printer lays down the right ratios of ink at each required level, from the lightest to the darkest colour, and that each step from light to dark is evenly spaced. When you ask your computer to send a colour that is 50 per cent cyan to the printer, for example,
50 per cent cyan is actually printed.
Standard drivers, like Epson’s or HP’s own, have a type of ink-limiting and linearisation pre-configured for their own papers. You are effectively selecting a linearisation and ink-limiting setting for that particular paper whenever you select a paper type from the driver dialogue. Most drivers do a reasonable job but the RIP method still offers advantages; not all printers are created equally, devices drift over time, and you can get small discrepancies in ink and paper stocks. But it’s with third-party media that you’ll really notice the differences: even with a custom profile, you’re constrained to selecting a manufacturer paper type that isn’t geared to that specific paper. Different papers absorb ink in different ways. By calibrating the printer for that paper stock prior to profiling, you can achieve far better results with third-party papers.
Profiling a non-linearised printer will take the device and media anomalies into account to some degree. A custom profile of an Epson printer and driver with a particular combination of ink and paper will compensate as best it can for the non-linearity of a printer/paper combination, but this is a compromise akin to profiling a monitor that hasn’t been calibrated. The profile is really pushed to its limits in terms of the conversion work that is required, and you can’t expect your printer to reproduce images to their full potential. Possible defects include poor shadow detail, posterisation and contaminated greys.
While many RIPs boast a reduction in metameric shift (the phenomenon of inkjet prints appearing to shift in colour locally or globally under different lighting conditions) by reproducing specific colours without the inks that are prone to colour shift, there are companies which are experts in producing a specialised form of calibration, profile-building, and profile editing to virtually eliminate the problem (www.pixl.dk is one such company). Being able to deliver fine-art prints to clients, safe in the knowledge that colours will remain consistent under a variety of light sources, provides an obviously measurable advantage.
Deciding on the RIP application that best suits you is another aspect of professional consultation – there are over 100 RIPs out there, including the likes of Proofmaster, GMG ColorProof, ORIS Colortuner, ProofGate and Best Colorproof.
Many RIPs will produce a very coarse dot-screening that’s fine for pre-press but not at all suited to the production of fine-art or portfolio prints. And, some of the RIPs labelled as suitable for photographic usage may not have all the functions necessary for optimum profile-building, such as control over light and dark ink blending for the smoothest of gradations with printers that utilise light versions of inks such as cyan
and magenta.
It’s worth noting that most RIP applications are certainly not plug-and-play. Colour-management professionals can spend months experimenting to get the best out of a single RIP application. Once successfully installed, calibrated and profiled by an experienced specialist, though, a RIP will be relatively easy to get to grips with, and will provide you with immediate gains in print-quality. On the other hand, a poorly set-up RIP might actually degrade rather than enhance the quality you’re already achieving with your standard driver. This means that you’ll need to budget for the installation as well as the software itself via a company such as www.colourmanagement.net (expect to pay between £2000 and £3000, or more for certified proofing). The alternative is to use a pre-configured RIP, such as Colorburst X-Photo (from about £350/$700 at www.colorburstrip.com). This can be used straight out of the box with profiles for popular papers downloadable online, although for best possible quality you’ll also need to invest in a spectrophotometer such as the x-rite i1Photo (about £850) to keep your printer linearised.
The dedicated RIP, then, is the best choice for those working in environments where that extra few per cent makes all the difference to exhibition prints, portfolio prints or photographs for sale. If you’re producing a handful of prints a week, or you’re not running one of the large-format printers, you’ll be better off with a pre-configured RIP, such as Colorburst X-Photo (or X-Proof if you want print certification).
Anecdotal reports from working photographers do suggest that RIPs are capable of improving print speeds by up to three times and cutting ink usage in half. A dedicated RIP also offers a nesting capability that automates layout for the best fit of multiple images, saving both time and paper. It doesn’t take too much of a mathematical brain to work out the potential cost and time savings of either type of RIP?application.
RIP HISTORY
The raster image processor (or RIP) was originally invented purely for the process of turning text and vector graphics into printer- and press-friendly, dot-based information (now achieved using a standard called Postscript). As image files such as TIFFs are already raster images, the raster image processing part of the RIP is of no interest to photographers. However, over the last few years, a number of colour-management and pre-press professionals have discovered that many of the workflow and calibration functions of RIPs have evolved, and are now incredibly useful in the photographic fold, offering a far superior alternative to the standard printer driver.
Today RIP software is no longer the preserve of the pre-press industry.
THE CMYK ADVANTAGE
For those who like to get down and dirty with CMYK, a genuine RIP offers the chance to drive a printer as a CMYK device. Standard printer drivers like Epson’s own are actually RGB-based – that is, they require RGB information which they then convert internally into CMYK data for the inkjet. Any custom profile you make of a standard driver/printer/ink/paper combination will be RGB-based. Send CMYK information to a standard driver and it will first convert it to RGB before converting back to CMYK, which is a good way to degrade your final print.
The CMYK capabilities of a RIP allow you to build CMYK profiles of your RIP/printer/paper/ink combination and so get directly involved in the process of how RGB data (or with proofing, press CMYK data) is converted and, specifically, how the K (black) channel is produced from the three-colour RGB file. It also allows the image maker to separate (convert) the RGB image to CMYK before printing, to better optimise image appearance pre-printing using Photoshop’s soft-proofing facility. Anyone who has complained of weak blacks with Epson Ultrachrome inks and matte papers really needs to see these functions in action.
Matt Henry
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