RGB or CMYK?

The debate continues between content creators and print providers. While creative people are excited by the flexibility and cost benefits of an open color managed workflow, they're often faced with uncooperative or downright resistant output providers.

It's true that the trend today is toward industry standard ICC profiles and an RGB-centric workflow. In this model, source artwork stays in a large, standard RGB working space for as long as possible. All color corrections are performed in this space, converting color only when targeting for various final outputs that may include websites, high-quality inkjet printing, and printing on press. However, many– perhaps most–print shops have no clue about how to handle profiles in files and workflows, are not prepared to receive RGB files, or firmly believe that a CMYK workflow is the only game in town.

In this article, I show how to provide reluctant printers with the CMYK files they demand ... while still allowing you to retain control over color. Here is a seven-step plan for surviving the times when you're required to work with printers who demand CMYK art.

1. Ask some questions.
Begin by asking your print provider questions designed to clue you in about their involvement with color management:

• Which file standards do they accept? RGB tagged or untagged? CMYK tagged or untagged?
• If they accept RGB tagged files, is there a recommended working space that matches their print conditions (example: ColorMatch RGB, Adobe RGB, etc.)?
• If they accept only CMYK art, do they provide separation information? Do they provide a press profile or proofer profile? If not, what printing standard do they recommend for the color mode conversion (example: US Sheetfed Coated v2, US Web Coated SWOP v2, etc.)?

Color-savvy prepress and print shops will make a press profile available to customers. In the absence of a press profile, they might offer a profile of their proofing system, which their press will ultimately match. These custom output profiles allow you to create accurate conversions, bringing you closer to your color matching goals. Also, a custom press/proofer profile makes it possible to accurately preview the printing onscreen (i.e., soft proofing), saving time and money on guesswork color correction/ proofing cycles.

2. Set up color settings in Photoshop and synchronize other applications.
To get the best results, create your color settings in all Adobe applications so that color management is fully enabled. You can set up one of the applications first, then synchronize color settings in all the rest of your applications.

I prefer to do this in Photoshop. Type Command+Shift+K (Mac) or Control+Shift+K (PC) to access Color Settings. From the Settings menu, choose North America Prepress 2 as a starting point (figure 1). This sets up a safe color-managed workflow, preserving all embedded profiles and warning you of missing profiles when you open files.

You can customize this setting by choosing the printer-recommended RGB working space. If your printer doesn't recommend a color space, try setting Colormatch RGB. This choice gives good results because it features colors with a close match to the typically compressed tone and color range of an offset press. Another reasonable choice in this case is Adobe RGB.

If the printer has provided you with a custom press profile, load it as a CMYK working space. Click the Save button to save the color setting with a unique name and with a .csf file extension. This will save the setting in the correct location on your operating system (see figure 2).

You can also add a brief comment about this setting, which will appear in the Description section of the Color Settings dialog.

I recommend that you immediately synchronize these settings in other Adobe applications. Do one of the following:

• In Adobe Creative Suite 2 you can use Bridge to do this. In Bridge, type Command+Shift+K to access the Creative Suite Color Settings. Click the Show Expanded List of Color Settings Files button and choose your custom Color Settings file. Click the Apply button to synchronize these settings across all applications in CS2 (as in figure 3).
• In previous versions of Adobe Software you can load this setting in the Color Settings dialog in any of the applications.

3. Calibrate and profile your monitor.
This step is essential for evaluating images onscreen in a color-managed setup. Invest in a professional grade monitor-profiling package with a colorimeter to calibrate and profile your monitor in one pass. Calibrating ensures an optimal tonal range and eliminates any color cast on screen, and is in fact the basis for viewing accurate color. Profiling your monitor allows you to accurately preview color conversions, and to perform soft proofing (previewing your printing on your monitor–see Step 5). This is a very good time to evaluate your aging CRT monitor to see if it can be traded up for a high-end CRT or a more stable LCD monitor.

4. Leave no file untagged!
Ensure that all files in your workflow are tagged with an identifying profile for the color management system (CMS). This is the only way for the CMS to correctly display and render colors in all of your applications. To assign a profile to a scanned RGB file that's missing a profile, or a client's file with no embedded profile that sneaked into the project, choose Assign Profile from the Edit Menu (Photoshop CS2– see figure 4), or from Mode in the Image Menu (previous versions). You can either assign a custom scanner profile that you created with profiling software or assign a standard RGB working space so the colors in the document will display correctly. If you can't tell where the file originated, try assigning ColorMatch RGB or sRGB, verifying that the colors are rendered adequately.

Optional: Normalize all art. This is an additional step undertaken by some to consolidate all artwork into one "container" or common working space such as ColorMatch RGB for RGB images. This process lends your images uniform details like the appearance of white, a target gamma (overall contrast), and a similar quality to the bright primary colors. (Don't convert your images if your CMYK scans were set up for a specific press.)

To normalize, choose Convert to Profile from the Edit Menu in Photoshop CS2 or from Mode in the Image Menu in previous versions. For RGB images, choose either ColorMatch RGB or the RGB working space recommended by your printer (see Step 1). Select Perceptual Intent and check Use Black Point Compensation, then click OK (see figure 5). Tip: Create an action or a droplet in Photoshop to automate these repetitive operations.

5. Soft proof your printing on your monitor.
Provided you have a good monitor profile and a decent profile representing your print conditions, you can preview printing onscreen. You may not be aware that a printer's profile captures a lot of information about printing conditions–in addition to the tone and color response of the print device, it also records how the inks interact with specified stock. This feature alone can save you lots of time.

Choose Custom Proof Setup from the View Menu in Photoshop. Choose your printer's custom press profile or proofer profile. If none is available, choose a standard printing profile that best reflects the print job (US Sheetfed Coated v2, etc.). Check Black Point Compensation and experiment with choices in the Rendering Intent menu to finesse the color conversion–common choices being Perceptual and Relative Colorimetric.

The most exciting part of this dialog is at the bottom left. Checking Simulate Black Ink lets you preview how the blacks in the image will be printed. This will immediately reveal if delicate shadow detail will survive the print job. Similarly, checking Simulate Paper Color will reveal the effect of printing on the chosen paper stock (figure 6). This is especially helpful when you're printing on uncoated stock or newsprint, because you can preview many flaws related to the limited dynamic range of this medium.

6. Color correct while soft proofing.
Once you click OK after Step 5, you're effectively soft proofing the profile, as indicated by the profile name in the title bar. This view can be toggled on/off by typing Command/Control+Y. Now feel free to color correct using all of your favorite editing tools to make the image shine– all while previewing its printed state (figure 7).

When you color correct in the RGB mode, you're ahead of the game. The RGB color spaces are generally larger than any output color space and handle colors and transitions smoother than CMYK output spaces. The printing medium dictates an inherently smaller color gamut and a "flatter" dynamic range. And since there is limited data to begin with, extensive color correction in CMYK has the potential to make some images posterize and fall apart faster than if they were corrected in a larger color space like RGB.

Working in RGB, you can be reasonably sure that corrections will be faithfully reproduced, taking into account basic differences in the two mediums. Tip: Create named adjustment layers for fixing output-related flaws, such as "Boosted 3/4 tones–Newsprint." This way, you maintain a master file with multiple layers to be applied at will during conversions, targeted for multiple output devices.

7. Convert a copy to final CMYK.
If you were happy with the soft proofing, you're all set to convert to CMYK mode. Instead of performing a default conversion by choosing CMYK from the Mode menu, use the Convert to Profile command. Here, you can dial in the exact same settings you used in the Custom Proof Setup dialog. You'll end up with a flattened, output-ready CMYK file that can be saved with or without a profile (per your printer's requirements), and can be safely handed off for press output.

Web resources: Color Management Tips and Tricks Tips on redirecting CMYK art for web publishing, fine tuning workflow, and meeting client demand for color-managed file support.

More resources:

• www.color.org
• www.FOGRA.org
• www.ECI.org
• www.digitaldog.net

Color management services:

• Rods and Cones
• The Color Management Group
• Chromix

Color management printing companies:

• Priority Litho
• O'Neil Printing
• Sandy Alexander

Recommended resources:

• Real World Color Management, by Bruce Fraser et al, $49.99, Peachpit Press
• nderstanding Color Management, by Abhay Sharma, $66.95, Thomson Delmar Learning
• ICC Color Management in Photoshop, by Rita Amladi, $99.95 (CD package; some free tutorials available online), Virtual Training Company

About the author Rita Amladi is the owner of Orion Arts & Communications, a digital imaging training and consulting company. She is a Certified Technical Trainer and an Adobe Certified Trainer for Photoshop. She teaches classes on Photoshop and topics such as color scanning and digital capture, color correction, digital special effects, and production techniques for print and web art. Her latest training CD is ICC Color Management in Photoshop 7 from Virtual Training Company.

This article was originally published in the February/March 2006 issue of Dynamic Graphics magazine.

Thanks to our friends at Jupiter Images for sharing this great info.