One of the biggest challenges in designing and printing Hexachrome jobs is proofing how the final piece will look. The Pantone Hexachrome print process provides an enhanced color gamut with the addition of orange and green inks to CMYK. Typical proofing scenarios are more accustomed to CMYK plus spot colors, not a color model based on six colorants. Still, there are several proofing options available depending on what you are hoping the proof to depict. Proofing can run the gamut from soft proofs—computer display—to various types of hard proofs. Correctly assessing your proofing needs will guide your selection of an appropriate Hexachrome proofing system.
Soft Proofs
The common computer display has very similar color regardless of brand. The subtle differences between computer displays is attributed to the type of phosphor guns used, such as those from Mitsubishi, NEC, or Sony Trinitron. The LCD market is enjoying steady growth which has fueled the development of high fidelity color displays for the graphic arts market.
Late last year, Eizo Nanao Technologies Inc. introduced the CG220 LCD display, boasting a color gamut close to the ubiquitous Adobe RGB color space found in Adobe products. Adobe RGB is the preferred RGB color space to use for Hexachrome jobs since it encapsulates a larger range of colors reproducible in Hexachrome printing. The pairing of the Eizo Nanao CG220 and Adobe RGB allows more colors to be seen uncompromised by the display’s color gamut.
Viewing an Adobe RGB file on a Sony Artisan display is going to have more colors compromised compared to the larger color gamut Eizo Nanao CG220 LCD. Even still, Adobe Photoshop does a pretty amazing job of dealing with this discrepancy.
So why not use a smaller color space like sRGB or ColorMatch RGB to define your files since they are based upon a typical computer display? These color spaces are much smaller and do not take advantage of the larger color palette of Adobe RGB that contains more printable Hexachrome colors. Having a computer display closest to Adobe RGB is ideal.
Separating Vector and Raster Objects
Adobe Photoshop CS2 and earlier do not provide correct previews of Hexachrome separations on screen, nor the functionality to convert jobs to Hexachrome. Third party Photoshop and Illustrator plug-ins are necessary to convert files to Hexachrome in Adobe products. Both GretagMacbeth, makers of ProfileMaker color profiling software, and Pantone offer solutions for Adobe products. Both offer similar functionality but with subtle differences.
Printed Proofs
There are numerous advantages and challenges of printing Hexachrome. Content creators, graphic designers, and photographers are afforded with an optimized color palette resulting in a more dynamic printed piece. For a content creator, it’s almost impossible to correctly predict actual Hexachrome print conditions since there aren’t any guidelines or standards to conform to. Each print provider has a different look because their printing system is configured differently, and thus unique.
The best approach for creating jobs destined for Hexachrome is to work within the RGB color model for bitmap files and specify color in vector jobs using the PMS spot color library or RGB values. The print provider will invariably do a better job converting your job to Hexachrome than you could do on your own, since they know their print conditions intimately. Separating files and sending them to a print provider will almost always require color correction and thus incur additional cost to print the job.
The most practical method of proofing Hexachrome separations for content creators is to evaluate the color on a properly calibrated computer display or in-house inkjet printer. Proof the RGB bitmap and vector files on a well calibrated inkjet printer that is not configured to simulate any print standard, just the best color rendering of the file. Though this method will not proof how the job is separated to Hexachrome, you will have a good sense of what is possible on the press. A print provider Hexachrome proof is still required for confirmation of press Hexachrome color.
Fine Art and Reprographics
For print providers, there are two general markets for printing and proofing Hexachrome jobs. The first market is where the final job is printed in Hexachrome on large format inkjets or solvent ink printers. This market is ideally suited for checking color and tonal balance on a computer display with a large color palette.
Mimaki, Mutoh, Roland, and Vutek offer products that can be configured with a Hexachrome ink set. These printers are commonly paired with either ColorBurst RIP or Onyx PosterShop. These RIPs allow Hexachrome calibration and specification of Hexachrome output ICC profiles for conversion of RGB, CMYK, and spot colors. They are capable of proofing press Hexachrome separations, but are not usually configured to do so on large format printers.
Flexographic and Lithographic
Print providers whose final product is on a flexographic or sheetfed press have different requirements of their hard copy proofs. This market needs to proof actual press separations typically as 1-bit TIFF or EPS files. While Hexachrome dot proofing systems have been available since the late nineties, many of these analog dot proofing systems are no longer being used because of the transition to computer to plate (CTP). Those that have transitioned to CTP use digital proofing systems and inkjet printers. High-end digital proofers like the Fuji FinalProof, Kodak Approval XP, and Latran Prediction 1420 (formerly PolaProof Digital Halftone Proofing System), are a few common Pantone-licensed Hexachrome proofers configured with special high fidelity donors to meet the expanded gamut. These systems work well but are costly to create proofs.
A veteran of Hexachrome inkjet printing and a Pantone-recommended Hexachrome inkjet printer, the Roland Hifi Jet Pro series has for years been the only available option to proof press Hexachrome separations on inkjets without a conversion to CMYK typical of most inkjet solutions.
RIP Requirements
A suitable RIP is needed to correctly communicate and calibrate in Hexachrome, not just CMYK and spot colorants. For years, that solution has been the AbsoluteProof product from Gimlé Limited. The AbsoluteProof can separate to Hexachrome for full gamut printing or proof press Hexachrome separations on a Hexachrome configured Roland Hifi Jet Pro printer.
Introduced at GraphExpo last year, Gimlé Limited’s AbsoluteProof Extrachrome solution uses the Epson UltraChrome inkset found in Epson 4000, 7600, 9600 printers for the base CMYK inks, but it replaces the light cyan and magenta with orange and green inks. According to Gimlé, the light cyan and magenta are not necessary since Epson has improved their inkjet technology to produce a smaller dot that obviates the need for the light inks.
Most RIPs that support Hexachrome capabilities do so by converting RGB or CMYK files to Hexachrome or just plotting postscript separations. Only a handful of products support proofing of six-color separated files to a six-color inkjet printer like the Roland Hifi Jet Pro II printer. This workflow is necessary for lithographic and flexographic printers. These users need to proof actual press separations on a proofer capable of rendering the file’s full color balance uncompromised by the inkjet inkset.
Proofing RIPs that only support CMYK inkjets must convert the press CMYKOG to CMYK. If the RIPs don’t support Hexachrome input ICC profiles, then the only method of proofing is to send an RGB proof file from either Pantone HexImage or GretagMacbeth MultiColor plug-ins.
The more mature RIPs support a six-color separation, typically a DCS 2.0 EPS or 1-bit TIFFs. This is the recommended approach to proofing press Hexachrome separations since file integrity is maintained, no interim conversions back to RGB are required, and the Roland Hifi Jet Pro II color gamut is larger than press Hexachrome color. Both EFI’s ColorProof XF and Gimlé’s AbsoluteProof offer this functionality with the Roland Hifi Jet Pro II inkjet. Onyx Poster Shop supports press Hexachrome separations and provides a means to specify a Hexachrome input and output profile for the color matching, but does not offer a dot proof option.
Your technology investment depends on what you want your proofs to convey. Epson Ultrachrome proofs can show the majority of press Hexachrome, but with some compromises. Roland Hifi Jet Pro II is still the leading solution. The Eizo CG220 LCD closely resembles the venerable Adobe RGB color space and provides enough color gamut to proof Hexachrome color on screen unlike traditional CRT computer displays.
Carefully evaluate the proofing needs of your customers to help assess which proofing option is best for them. Adding Hexachrome proofing can improve customer satisfaction and less surprises in a final Hexachrome printed piece.
