Separate Yourself

Use of RGB images is on an upswing, thanks to the burgeoning supply of multi-megapixel digital images from surprisingly affordable cameras, as well as the growing availability of high-quality stock photography in RGB mode. Allowing graphic designers to place their RGB graphics directly into page layout programs (without first converting the assets to CMYK) is an emerging workflow within the creative community.

“It took a little time, but now everyone is comfortable retouching and placing RGB-mode images,” admits Bob Thompson, imaging manager at Sports Illustrated (SI) magazine. “It's a less-destructive mode of retouching that appeals to us, especially since we've gotten very proficient at making exposure adjustments in our 'raw' file [digital negative] viewer before opening the image in Photoshop as a 16-bit file.”

After final approval of the image, the SI imaging team applies unsharp masking and converts the file to 8 bits per channel before sending the image to its Xinet FullPress server.

“The Quark pages supplied to us already have FPOs placed by the art department,” notes Thompson, “so we print RGB out of Quark, then let our Nexus RIP pull in the color-separated images from the FullPress OPI server.” Abandoning a history of manipulating CMYK images was not that difficult for the SI Imaging Department. According to Thompson, “It took a while for some of our more experienced operators to give up editing in CMYK, but now everyone is on board with the RGB workflow. I think people will prefer it in the long run.”

The traditional solution when client files arrive chock full of RGB images has been to ask the color separator to convert these errant images to four-color process CMYK data. Charged with scanning, retouching, balancing and proofing critical color images, this skilled technician is also referred to as “the person who knows everything about color.”

Back in the day when high-quality prepress meant drum scanning a 4×5´´ transparency directly to cyan, yellow, magenta and black negatives, the color separator learned which knobs to tweak to take the green out of the magentas or the black out of the reds.

Compare that parting glimpse of the past 20 years with today's new JDF automation capabilities, and it's clear that color separation in its current form is still too manual. An automated RGB workflow increases processing speed, offers a smaller file size, makes color corrections easier and allows the choice of a press-specific CMYK right at the moment of output. Distilling this PostScript into a PDF/X-1a document for final client sign-off can be a real time-saver.

Color expertise and excellent eye-hand coordination gave the color separator the requisite skills for editing image contrast, color or sharpness. Today's efficient RGB workflows place these retouched RGB master images directly into page-layout applications such as QuarkXPress and Adobe InDesign. Perhaps most importantly, those complex CMYK conversion curves from Photoshop's early years have finally disappeared. Color consultants promote the ideology that even generic ICC profiles create more consistently accurate color separations than those old handcrafted equations.

Adobe and Quark have lost no time incorporating color separation capabilities within the domain of their page layout applications. Both InDesign (and Creative Suite) and QuarkXPress allow users to select the document's RGB and CMYK color space, and both allow document default settings to be customized for an individual graphic.

By harnessing the powerful color management engines of the latest versions—Adobe InDesign CS2 or QuarkXPress 6.5—graphics of nearly any color space can be automatically converted into precisely calculated CMYK PostScript. It's fundamentally tweak-free color separation, offering consistency and automation in place of expert judgment and the pinch of experimentation formerly required.

For projects where price is as great a concern as quality, or for clients who value turnaround time more than all that value-added retouching you've been delivering to them, consider the ease with which RGB-mode images can be automatically converted to CMYK during the PostScript output process. For print shops with a variety of presses, the need to assure that color consistency will be maintained even while moving projects from web presses to sheetfed (or from offset to digital, for that matter) can also serve as a big motivation for the adoption of an RGB workflow.

In such situations, consistently high-quality results can be generated automatically by placing high-resolution RGB graphics into your favorite page-layout program. Distill this output into a PDF proof file that carries an embedded RGB profile as well as rendering print output intent information, and then select the appropriate press profile to generate an on-screen CMYK simulation. At output time, enable consistent results across several different printing presses simply by swapping out the CMYK press profile as appropriate.

If page-layout applications can also function as late-binding color separation engines, can a basic prepress workflow benefit from a more extensive use of RGB graphics? Real-world field testing has revealed consistently high-quality results for all-RGB test documents output from Adobe InDesign CS2 and QuarkXPress 6.5.

The test document also included spot-color and RGB text, as well as two EPS files created by Adobe Illustrator CS2 but saved as a “legacy” EPS with Illustrator 8 compatibility.

To get an apples-to-apples comparison, one of the Illustrator files was built in RGB mode, while the other was built as CMYK. Both included black outlines and Pantone spot-color fills. PostScript files were generated from each program as both color separated and composite CMYK, using the Acrobat Distiller PPD. When converted to PDF through Adobe Acrobat Distiller 7, these virtual proofs allowed evaluation of the results using Enfocus PitStop.

The results: With both applications, conversion of RGB images into CMYK mode, done on the fly during the PostScript output stage, yielded results that matched Photoshop's conversion from RGB to CMYK. Spot colors in imported EPS files were respected regardless of the source document's color space. Worth noting is the fact that only Adobe InDesign offered the ability to color manage the conversion of spot colors into process builds through the use of L*A*B values.

As expected, both programs converted RGB blacks in vector artwork into a mixture of all four process colors. (Black text and rules created within both page-layout applications did correctly separate to just the black channel.) Unfortunately, QuarkXPress 6.5 offered no option to color manage the appearance of spot colors via L*A*B and was not able to separate placed PDFs containing RGB images.

Support for RGB graphics has been increasing over the last decade, and the new versions of QuarkXPress and Adobe InDesign offer an array of color-management features. These complex options let you convert incoming RGB, grayscale, L*A*B and CMYK source documents into composite or color-separated output—without the need for an experienced color separator.

One major shortcoming was detected during field testing: Instances of RGB black (R0 G0 B0) created outside the page-layout application will separate into percentages of all four process colors (rather than black only). To avoid this dreaded “four-color black,” create documents in CMYK color mode when using Adobe Illustrator or other vector-graphic programs.

Of course, the occasional RGB EPS file will undoubtedly sneak through—and that's the time for PDF editing tools, such as Enfocus PitStop Professional. PitStop can globally replace all instances of C75 M68 Y67 K90 with black-only at 100%. It's also useful for bringing rogue PDF files into compliance with PDF/X. Check out Enfocus PitStop Server for a range of workflow automation options.

For more advanced capabilities, including color editing and remapping, consider the wildly popular range of PDF workflow RIPs—examples include Agfa Apogee, Creo (Kodak) Prinergy, Dalim Twist, Esko-Graphics' Scope, Heidelberg Prinect and Screen TrueFlow, to name just a few. All major offerings can produce process and spot color separations from a composite RGB PDF. In-RIP separations and in-RIP trapping are time savers, so check your system to determine the available features. Are you placing a lot of big, high-resolution images? Server-based color separation, as implemented by Xinet's FullPress, can combine the power of open prepress interface (OPI) image replacement in conjunction with on-demand CMYK separations. Helios legendary EtherShare OPI also combines image swapping with concurrent process color conversions.

If your raster image processor doesn't offer enough color management capabilities, consider augmenting your RIP with additional color-management software. Options include EFI's BestColor, or other competitors in its class such as CGS Oris Color Tuner, GMG ColorProof and Onyx Graphics' Onyx Proof in addition to systems offered by the manufacturers of digital proofing hardware devices.

Accurate proofing requires an extra level of profiles and calibration, so consider the services of a reputable color management consultant before you begin—and make sure the consultation includes documentation of all new processes as a Standard Operating Procedure document.

Implementing an RGB-enabled design or prepress workflow doesn't have to be extraordinarily complex to be effective. When used in conjunction with your “standard” production methods for legacy jobs, it allows you to automatically render your documents into the most appropriate color output at the last possible moment. Saving your preferred settings in the form of a Standard Operating Procedures document can help assure consistent results.

Adjusting for changes in print engines without modifying the content of your documents can benefit any company that is operating with more than one printing press or across multiple devices such as digital print engines. Designers will love the freedom to create and store assets using RGB's larger color gamut yet smaller disk space requirements. (It's intuitively obvious why this should be so: The three channels of an uncompressed RGB document will occupy only 75% of the space that is required for a same-size CMYK document.)

Today's business realities call for maximizing your efficiency during every step of production. Leverage the power of color management to produce your CMYK on the fly, and you'll separate yourself from the competition.