Digital proofing is going mainstream, but it's not as cheap or easy to implement as you think.

In the good old days, proofing was an arduous task. Take the design files, make film separations, mix up Cromalinw powders for the spot colors, contact them to donor sheets and make up a proof. It cost a lot in terms of time and money, but you got a very accurate representation of what the final packaging was going to look like—right down to the traps and halftone dots.

High-end digital proofing has been around for a while now, but the primary focus has been on process-color work, and spot-color support is still limited with the halftone-based systems. These have been supplemented with sophisticated inkjet-proofing systems that output very accurate color—without dots. Purists scoffed, but the proofs were too good to ignore—though the $50,000 price tag was tough to swallow.

Then the floodgates opened, as consumers purchased inkjet printers for use with their home computers. While niche applications such as packaging are a mere blip on the profit screen at Epson and Hewlett-Packard, their efforts to cash in on the digital photography bonanza has made it possible to generate highly accurate proofs.

So now that you can purchase a 6- or 7-color piezo-inkjet device for a few thousand dollars, how close can you match your customers' custom colors? The answer: closer than you might think. But it won't be as cheap as you might think, either. It takes a lot more than an Epson 4000 to generate accurate color proofs; the real issue is setting up a workflow that can consistently do it and that requires investment. Get ready to drop about $15,000-$20,000 to set up a system capable of matching your customers' colors and expectations every time.

On the hardware front, inkjet is preferable to laser printing because it's less susceptible to changes in environmental conditions. Furthermore, while technological advantages are fleeting, Epson clearly has the edge as a result of its Ultrachrome inks, which offer excellent stability (fade resistance) along with an extremely broad gamut.

The key to leveraging the hardware is the RIP. Currently, there are several vendors with digital inkjet-proofing solutions suitable for packaging applications, including Agfa, CGS ORIS, Creo, DuPont, and GMG FlexoProof. Of these, only Agfa, Creo and DuPont offer turnkey solutions.

Another essential component is the media, which is why all the credible proofing systems comprise or specify paper/stocks in addition to software to drive the printers. You need to evaluate media for gamut and total ink limit.

You'll also need a spectrophotometer (not a densitometer) to measure L*a*b values. One of the sticking points here is that all partners should be using the same measuring devices to eliminate differences in the way the color is measured and interpreted. If you're using a GretagMacbeth model, and your client is using one made by X-Rite, you can just about guarantee you'll have problems getting colors to match.

One reason why ICC color management often mangles colors is that people erroneously assumed that all ICC profiles define and interpret color the same way. Sadly, this is not the case. As a result, this is one area where you should go with a RIP that has its own proprietary color-profile linking technology, or at least one that supports ICC device-link profiles to integrate with other RIPs.

Once the pieces are in place, the next step is to calibrate everyone's system to the reference point—which should be the client's known color standard or the printing press. This is best accomplished by hiring an expert consultant to generate profiles that calibrate each system to match the reference and ensure that the same methodology is used at each site. Once in place, each party can linearize their system. With some systems, such as DuPont's new b2, this happens automatically and in real-time using the Internet; other systems require the operator to read the strips and compare it with the reference point.

Since spot colors make up a majority of many packaging jobs, how they're rendered is an important issue to consider. CGS ORIS ColorProof, for example, requires a separate channel for each spot color and uses the spectral values to drive the inkjet heads. Similarly, it's important that the system renders tints, not just solids, on custom colors, as well as how they behave when mixed with other colors.

Trapping, always near and dear to packaging professionals, is another area that must be worked out. Do you need to see traps? At which stage of production? Either way, this issue will be determined by the design/application files, not the RIP, and you should look for systems that accept 1-bit TIFFs.

Finally, there's RIPing: do you need to make your plates from the same data as your proof or is it okay to re-RIP for each? Though a semantic issue for some, if you're producing medical labels, this is an issue with legal and financial implications. Creo's proofing solutions enable you to make proofs from the same bitmap data as will be used to make the plates. In addition to accepting 1-bit TIFFs, GMG's new FlexoProof offers separate dot-gain curves for the platemaking step and the printing step, so you can see how much the large flexo-halftone dots gain at each stage and on different substrates.

The bottom line: While it's not as cheap or easy to implement as some would like to think, inkjet-based digital color proofing can satisfy the needs of package printers and their clients in the vast majority of cases. The tools are out there and, with some care, can accurately and consistently show what the press is going to print.