If it’s all the same to you

Inkjet as a process does not have the same principles that can be applied to it as, say, offset printing. It doesn’t have the ability to stick to the standards that are used in analogue production and, as such, it is dependent on how its varying processes and devices see colour and how to reproduce it. Those steeped in pre-press tended to understand about colour and had a set of rules and charts to help make sure that what came out of the resulting offset press was correct. The trouble (if it can be called that) we find today is that anyone can sit in front of a computer, run up a graphics package and produce the bones of a display. If it looks okay on-screen then that should be sufficient to render the colour accurately when the job comes out of the printer. Rarely does this happen; indeed, if this happy occurrence does take place it’s purely down to luck.

When producing jobs for wide-format inkjet output, colour management relies on a host of different criteria that are needed to control what comes out of the other end. Applying a generic standard for digital production is tricky because there are so many elements involved, with many of these being controlled not by a set of applied algorithms but via several component parts each of which build up to affect the finished job. In offset and screenprinting, ISO 12647 comes in with specific process parameters whose values are applied to encompass the different parts of the production stages. For example, the screen process uses ISO 12647-5 which takes into account the idiosyncrasies encountered, such as colour separation, proofing and printing. These differ to the parameters used in other areas of graphic technology, the most common probably being ISO 12647-2 which has specifics for four-colour offset printing and which now accounts for direct-to-plate as well as via traditional film.
Without such a standard applying to wide-format digital print - yet - those specialising in inkjet and who need to be able to use a stated set of criteria are pretty much still in the dark. It should be easy, surely, to translate the principles of ISO 12647 but, in reality, it isn’t; and this is because there are far more digitally driven variables which need to be factored in than the equivalent to be found in analogue printing.

Controlling the process in wide-format is reliant on how the data is prepared and PDF format offers a classic example of a standard in its own right yet one which is affected by the data it is given and how it reacts when output through an ink-jet system to an end material. We can say that PDF is good because it adheres to its own set of rules with ISO 15930-8 but this encompasses the dissemination of digital data in terms of identification and inclusion; however, it does not provide control over the colour determinants which are held therein.

Colour used in a job has to be determined by a set of factors which uses standards to suit an input or output device. With the help of the International Color Consortium, the resulting definition or ICC profile for correct colour reproduction within a specific colour space should ensure that fidelity is maintained across monitors, scanners, printers and, even, digital cameras. So a system which has no ICC colour management requires profiling so that the device’s colour space can be adjusted to a controlled equivalent in order to produce an accurate result.
Today most software applications include a choice of ICC profiles to make the job easier, in the same way that output devices, or printers, can add them for different materials on the host computer at the time of driver installation. This profile support has to go further, however, because it is not only the input device, the software and the output device which need to consider the correct colour algorithms. The material being used for the application also needs to be factored in according to parameters including coating, absorbency and reflectivity.

The inkjet waters are muddied further because many printers contain more than the basic four colours of CMYK and need to generate these additional channels from RGB or CMYK data with the intention of improving the gamut. Many will argue that the improvements in today’s greyscale variable dot printheads do not need the additional options of light cyan and light magenta or other fancy shades to generate smooth graduated tints and more accurate colour. But, nonetheless, what you perceive to be the colour information generated in your origination is not what is sent to the printing machine. In fact, it is the driver or the Rip that provides the transformation and the information used is determined by the ICC profile. Thus, an ICC profile will not determine the specific numbers of inks used in a printer, nor will it correct unwanted artefacts such as colour casts. In the same way, a profile cannot improve a narrow gamut, such as sRGB and make it wider so that the colours will render properly; if the colours are missing in the first place, it isn’t possible to get them back. Likewise, an ICC profile isn’t a correction device and won’t put right errors in the original data.

In simplistic terms, when a job is generated the application on the computer will convert the file to the chosen colour space, normally a calibrated RGB work space such as Adobe RGB (1998) which has a far wider gamut, or ability to determine colours accurately, than sRGB whose narrow gamut is fine for internet reproduction limited to viewing on-screen. When the job is sent to the Rip, the image is converted from the working space on the desktop to the required colour space via the correct profile.

Experienced studios and printer operators know how to get the best colour from their devices, all based around using the most suitable ICC profiles or from creating their own with the help of a spectrophotometer. This latter is essential when working with unprofiled media. The rendering intent used in the ICC specification handles the problems incurred with clipping, where inaccurate representation can lead to incorrect destination colours. The common associations are absolute colorimetric, relative colorimetric, perceptual and saturation, with the first two only differing in their handling of white point media adjustment and the latter two being preferred often for colour separation and for colour saturation where actual hue isn’t as vital as impact.

A true colour managed workflow goes far beyond a bit of monitor calibration and the application of a few ICC profiles. Growing numbers of print service providers are now being asked to produce the same input data with the expectations that it will match the output from various destination devices. These could be inkjet printers using different ink formulations, proofing which must be good enough to emulate the finished print run or, even, the same printer being used to output the same graphic onto various different types of media.

Rips contain a fair amount of colour management capability but, where greater levels of fine tuning and consistency are required, it’s often time to bring in the experts. Thus, it is hardly surprising that specialist companies have decided to develop colour management software designed to take the pain out of ink-jet printing. This solution is even more obvious when you consider that there are advertising agencies and design studios located miles away from the print house yet expect to be able to produce proofs which can be matched from one remote location to the next to the necessary levels of accuracy. No-one wants a horrible shock when prints from different sources are lined up side-by-side and look completely different in colour terms.

GMG, for example has software which uses hot folders for automatic conversion of colour for all print processes, including different colour spaces, plus the ability to profile and calibrate various output devices coming under the digital remit, including wide-format printers. It’s even able to reduce the incidence of chromatic colours to save on ink usage without compromising colour integrity. Likewise, EFI’s Fiery also helps users to generate consistent colour across different machines, with its open platform technology meaning it can be integrated into all environments, as well as wide-format. And there are growing numbers of companies moving into this sector, including CGS and FourPees.

For colour management to work in any environment, it really needs to start at the end and not at the beginning, for it is the printed product which determines the acceptability of the colour criteria put in place as the job passes from design and creation, through the Rip and on to the output device. This observation is really common sense, particularly taking into account the fact that rarely do two individuals agree on implementation in order to generate a faithful environment on a desktop which can be maintained throughout the entire printing process.

Successful colour management relies on the sum of its parts, but these parts need to be organised in such a way that the operator’s capability and the implementation of the processing do not compromise one another. In truth, and in a perfect world, any user should be able to rely on a standard set of rules so that it makes no difference who is at which end of the production process. In practice, this isn’t the case, and that’s why wide-format digital inkjet needs compliance with its own ISO standards which must be adhered to and honoured.


Bluetree turns to GMG

Bluetree’s range of digital equipment provides great versatility, but, it has also brought new layers of complexity in the area of workflow and file management. The company runs six digital inkjet machines: a roll-fed Epson Stylus Pro 1180 and Scitex XP2700, a flatbed Inca Spyder, a Develop Ineo 5501 and two flatbed HP Scitex FB7500s. Ensuring consistent colour across all six is no easy matter.

“Each manufacturer has its own Rip, and because technology has moved so quickly, each Rip is effectively from a different era,” says managing director Bryan Shirley. “We also had issues with colour consistency from one device to the next, and in matching corporate colours with the level of precision we required. The bigger the client, the more important correct colour becomes, and either directly or through agencies we have been producing for some very well known national and international brands.”

In order to address these issues, Bluetree turned to GMG for its ColorServer and SmartProfiler colour management solutions. “One of our machines had a GMG Rip, which was always reliable, so we already had a positive view of GMG. Once we decided to go for GMG ColorServer and GMG SmartProfiler, we quickly began to reap the benefits and I can honestly say it’s had a big impact on our business,” says Shirley.

One of the tangible benefits of the GMG workflow is in the prepress department. “Consistent input is as important as consistent output. We have all sorts of artwork coming to us, created in a variety of ways in a variety of formats, and in a worst-case scenario the files wouldn’t even be recognised. GMG ColorServer reliably automates tasks such as transparency flattening and CMYK colour conversion so that no matter how the original is presented, a quality job is presented to the Rip, and it doesn’t matter which Rip. This means far fewer hold ups in prepress.”
SmartProfiler is another time-saver, as Bryan explains. “This is vital, considering the variety of output devices we have. We pick the right media, the right device and the right running speed for the job, then just drop the file in the right folder, where it is queued for output. Once all the profiles are set up, it couldn’t be simpler.

“The main thing it’s given us is confidence. With an almost infinite range of variables from artwork, substrate, Rip and output device, I can never offer an absolute 100% guarantee of consistency – but I can now look a client in the eye and tell him his job has gone through a GMG workflow, which means it’s as close as anyone can possibly get,” enthuses Shirley, who’s company now employs 40 staff and is on course for a £4m turnover in the coming year.