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 colormanaged
workflow, they’re often faced with uncooperative
or downright resistant output providers.
It’s true that the trend today is toward industrystandard
ICC profiles and an RGB-centric workfl
ow. 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 professionalgrade
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.
Figure 5
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.
Figure 6
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).
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.
SIDEBAR: All-Out CMYK Workflow? Not All-Out Bad.
The trend may be headed elsewhere,
but in some situations a complete CMYK
workflow is appropriate. If you receive
CMYK scans that are fi ne tuned for specific press output, it makes little sense to
convert your art to RGB for editing.
In this case, color correct using small
moves in CMYK, taking care to see that
your editing does not violate any specified
ink limits by making excessive contrast
and saturation adjustments. Before you
edit the scans, request ink limit guidelines
from your printer (for example, “highlights
to be set no lower than 3% Cyan,
2% Magenta, 2% Yellow, and 1% Black”;
get similar guidelines for shadows and
the total ink limit). If you’re working in
Photoshop, you can place Color Samplers
at appropriate highlight and shadow
points in the image and monitor them
constantly using the Info palette set to
display Total Ink Limit. Be sure to request
an interim proof after performing any significant color corrections.
Note: If you need to repurpose the artwork
for another CMYK printer/separation,
or if you will post it to a website,
request an RGB scan. In this case, you will
most likely be responsible for the quality
of the final conversion to CMYK.
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:
Color management services:
Color management printing companies:
Recommended resources:
Coming up: Next issue, I’ll show how to set up an “ideal” (and
flexible) RGB-based color-managed workflow suitable for both
print and web design projects.
