Digital Prints

Welcome to ICC Color Management
In 1993, the International Color Consortium (ICC) was formed by eight industry vendors
including Adobe Systems, Eastman Kodak, Apple Computer, and Microsoft. Their
goal was to create and encourage the use of an open, cross-platform color-management
system to make consistent color reproduction a reality. The ICC Color Management
System comprises three components:
1. A device-independent color space, also known as the Reference Color Space. CIE’s XYZ and
LAB are the two related color spaces chosen by the ICC; XYZ for monitors, LAB for print
devices. To get consistent color across different devices, a transform (a fancy word for a
mathematical process) is needed to convert the colors from one device to the other. It’s all
about from and to. Source and destination. Monitor to printer, for example. But what actually
happens is that the transformation takes place through an intermediary color space or
PCS (Profile Connection Space).
2. Device profiles that characterize each device. An ICC device profile—note that the Mac world
calls them ICC profiles, and the PC world, ICM, but they’re really the same thing—is a digital
data file that describes a device’s capabilities and limitations. It’s like an equivalence dictionary,
and it works like this: If you characterize (or profile) any input, display, or output
device by relating its specific color space values to a known reference space, then any image
file moving from one profiled device to another can be rendered so that the image looks the
same (has the same values). This can apply to scanners scanning images, monitors displaying
images, and printers printing images, and there are ICC profiles for each situation. The
profile is actually a fingerprint of the device or process, and it helps each new device in the
chain understand what that image is supposed to look like—objectively.
3. A Color Management Module (CMM) that interprets the device profiles and maps one color
gamut to another. CMMs are also called color engines, and they use device profiles and rendering
intents (see “What Is Your Intent?”) to “map” any out-of-gamut colors into a reproducible
range of colors by the next device. (As you move down the production line from
capture to display to print, the color gamut gets smaller and smaller. Think of the funnel.)
Apple uses ColorSync as its color architecture, while Microsoft uses the comparable Image
Color Matching (ICM 2). Both ColorSync and ICM 2 rely on CMMs and ICC-standard
device profiles (with .icc file extensions) that contain information about how to convert colors
from one color space and color gamut into another. Photoshop can use ColorSync or
ICM 2 on each platform but by default uses the built-in Adobe ACE color engine for its
CMM. This makes highly consistent cross-platform color possible in Adobe applications.
The bottom line on CMS is this: instead of using eyes and a brain, which are easily fooled,
a color management system utilizes cold, hard, unbiased numbers. Easiest thing to do is
just delete this part. It’s already explained above in text and with ILL0405.A CMS helps
you calibrate, characterize, and finally print your images accurately and predictably. It’s
more than WYSIWYP, it’s WYSIWYPET—What You See Is What You Print, Every Time.
At least, that’s the theory.
A quick note: To utilize a CMS, you also need to have an ICC-savvy image-creation or
image-editing software program. There are actually three possible places to do color management:
(1) at the printer driver level, (2) at the application level, and (3) at the operating
system level. The application level is best.
Chapter 4 ■ Understanding and Managing Color 127