Digital colour proofing

Digital colour is at the heart of every graphic communications business.

Technological advances in inkjet printing have now enabled inkjet printers to produce high-resolution, stable colour proofs. New research reveals that inkjet has become the top technology in the digital proofing arena as well. Continuous-tone inkjet printers, like the old Iris proofers, basically defined inkjet proofing in the past, but these machines have now been surpassed by piezoelectric inkjet technology.

Epson, with its new ultrachrome inkset, seems to be the leader in providing stable, reliable proofing printers, in sizes ranging from 17” to 44” output. But another key element to consider besides the printer is a reliable RIP. In this month’s column we have chosen to feature the new EFI Colourproof XF RIP.

As a professional working in this world of digital colour, you have to accept colour data in a host of formats, process it and deliver it to a variety of output devices – offset, flexo, gravure, silk screen and digital presses and wide-format inkjet printers – located in the next room, or the next continent.

The backbone of EFI’s workflow is fast, flexible, easy-to-use, consistent digital colour proofing. EFI Colourproof XF’s combination of power, flexibility and expandability will allow you to meet your proofing needs not only today, but tomorrow.

What makes EFI Colourproof XF unique?

First, EFI Colourproof XF is scalable by size of network. Whether you install the complete product on one computer or need to provide 23 workstations with proofing services from one server, the software covers virtually every network configuration possible.

Second, EFI Colourproof XF is scalable by functionality. Starting with a basic package, you can add Product Options and Output Options.

Third, EFI Colourproof XF is easy. XF’s state-of-the-art user interface enables even inexperienced users to achieve top-notch proofing results. No relevant setting is more than two mouse clicks away from the main window. Training effort is low; installation and integration of EFI Colourproof XF is easy.

Fourth, EFI Colourproof XF sticks to open standards. It is cross-platform and complies with ICC, JDF and PDF/X. That makes it easy to share jobs, profiles and settings within and beyond your operation.

Choosing a printing device

What makes a particular printer qualify as a high-end colour proofer is whether it has the colour accuracy; resolution and predictability needed to consistently and reliably represent what will appear on press. If a colour printer shows unstable behavior in the inkset, it cannot be used for press-matching proofs.

Standard inkjet printers are proving popular for proofing applications when correctly colour managed and I believe that the micro piezo electric print-head technology has the edge over thermal print heads. The key to inkjet proofing is the short to mid-term stability of the inks as well as the obvious colour control required for the system. The micro piezo technology is more consistent and is not as affected by the same environmental conditions as thermal technology is. Also, the thermal process requires that the print-heads be replaced more frequently – which means that the system has to be calibrated on a much more regular basis or varying degrees of colour change can result.

Epson’s proofing qualities have been greatly improved over the last 2 years by the development of the Ultrachrome inkset. These inks are halfway between a dye and pigmented water-based ink and are very stable; with tests showing a Delta E shift of less than 1.1 over a 12-week period. A feature of Ultrachrome ink droplet is that it’s contained in a resin particle that limits its spread when it’s put on the substrate, thus enhancing Epson’s maximum resolution of 2,880 x 1,440 dpi.

While I believe that Piezo inkjet printers are better suited to colour proofing and higher end colour applications, the Epson range of inkjets do have the limitation of being no wider than a maximum of 44 inches wide.

The success of inkjet CTP proofing depends very much on who installs and calibrates the printer and RIP. Profiling the RIP to the customer’s chosen proofing standard or press, means narrowing down the colour gamut to make it easier for the press operator to match the resulting inkjet proof.

Colour management standards

It’s important to get a RIP and proofer that is SWOP certified. SWOP is one of the most widely used ink standards and there are several proofers that are SWOP certified (Best, Epson, Canon, Creo, Dupont, GMG, HP, KPG and Oris). This is an indication of the device’s output quality.

Treck-Hall supplies a variety of Rips and colour management solutions and can incorporate the individual characteristics of the press and meet industry standard profiles.

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