Adobe ACROBAT 3D Manual page 709

About color management
Color-matching problems result from various devices and software using different color
spaces. In a sense, each device speaks its own color language, and it can't communicate
that color very well to another device. One solution is to have a system that interprets and
translates color accurately among devices. A color management system (CMS) compares
the color space in which a color was created to the color space in which the same color
will be output, and makes the necessary adjustments to represent the color as consistently
as possible among different devices.
The following components are integral to a color-managed workflow:
Device-independent color space
To successfully compare different device gamuts and make adjustments, a CMS must use
a reference color space--an objective way of defining color. Most systems use the CIE
(Commission Internationale d'Eclairage) L*a*b color model, which exists independently
of any device and is an international standard for color measurement. For this reason, CIE
L*a*b is considered device-independent.
Color objects can be edited in a device-independent color space that is larger than the
color space of the output device, such as a computer monitor, a TV screen, film, or a four-
color press. Color objects can then be saved with profiles that contain information
describing the characteristics of the source and output color devices.
This makes a color-managed workflow advantageous. The objects become portable,
because they can be displayed on widely differing devices simply by tagging the objects
with different destination ICC profiles.
In contrast, device-dependent color varies depending on the device that produces it. An
object (a vector drawing or bitmap image) with a device-dependent color space displays
colors that depend on the hardware with which the image is created and output. Device-
dependent color works best when each part of the imaging process is controlled. For
example, at a prepress service provider, the scanner is calibrated to digitize color in a
photo accurately; the electronic image is then displayed on a particular calibrated monitor,
and the resulting file is printed on a particular calibrated printer. All of these devices are
calibrated to display color accurately from one device to the other.
Color management engine
Different companies have developed various ways to manage color. You can choose a
color management engine that represents the approach you want to use. Sometimes called
the color management module (CMM), the color management engine is the part of the
CMS that does the work of reading and translating colors between different color spaces.
Color profiles
The CMS translates colors with the help of color profiles. A profile is a mathematical
description of a device's color space--that is, how the reference CIE values of each color
in the color space map to the visual appearance produced by the device. For example, a
scanner profile tells a CMS how your scanner "sees" colors, so that an image from your
scanner can be accurately translated into the CIE color space. From the CIE space, the
colors can then be translated accurately again, via another profile, to the color space of an
output device. Adobe products use ICC profiles, a format defined by the International
Color Consortium (ICC) as a cross-platform standard. Adobe products also support
Microsoft ICM (Image Color Management) profiles and system-level CMSs on Windows
XP and Windows 2000.
Rendering intents
No single color-translation method can manage color correctly for all types of graphics.
For example, a color-translation method that preserves correct relationships among colors
in a wildlife photograph may alter the colors in a logo containing flat tints of color. Color
management engines provide a choice of rendering intents, or translation methods, so that
you can apply a method appropriate to a particular graphic element. In Adobe Acrobat,
you specify rendering intents when you create the PDF file, using Adobe PDF settings.
(See Color options.)
Note: Don't confuse color management with color correction. A CMS won't correct an
image that was saved with tonal or color balance problems. It provides an environment
where you can evaluate images reliably in the context of your final output.