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Color Management
I. Introduction
An image editing workflow can produce fairly consistent colors between
different output formats when
used along with a color management system. GFDL has the tools to
prepare color managed graphics for screen (TV, projection, internet)
& print with the help of ICC color profiles. The benefits of a managed workflow include the ability to
preview on-screen what a hard-copy print may look like, and the
assurance that a true hard-copy will resemble the image creator's intentions.
A workflow without color management (Figure 1) poses the problems of
- slow turn-around for color agreement between author & publisher,
- costly correspondence, and
- ad hoc approximation to color gamut mapping
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| Figure 1 Workflow without color management. | Figure 2 Color managed workflow. |
A color managed workflow (Figure 2) eliminates these problems, making the experience acyclic between author & publisher. The components that an author configures for such an environment to work are highlighted in Figure 3.
Figure 3 Image data flow in GFDL's Color Managed Environment. The image author is only responsible for several components: Image, Image (Working) Profile, and Printer (Output) Profile
II. Editing Images with Illustrator
- For print, request from your publisher an ICC printer profile. If it's standard (they'll say so) then we may already have it, otherwise they'll need to give you a file. In that case, inform the System Administrator to install it.
- Log onto the desktop publishing pc as guest in room 104. Then ftp any images that need to edited. ftp is available from the terminal or via RBrowserLite.
- Open the image with Illustrator. You should receive a prompt to select
a working color profile. If your image doesn't have a profile, assign
Adobe RGB (1998), otherwise select "Leave as is". However, it is very important
that a profile is assigned and embedded with the file, otherwise
the publisher will arbitrarily map your color's to their's.
Figure 4 Color profile assign window when a file is opened
- Save the file with the new embedded profile (File | Save As...).
- Duplicate your image's window. This will allow for a realtime on-screen proof of the image as it might look once rendered to a printer, screen, etc. From the menubar, select Window | New Window.
- Enable on-screen proofing for the duplicate window. From the menubar
select View | Proof Setup. Select your output's profile, which may have
been provided by the publisher.
Figure 5 Soft (onscreen) proof setup window
Intent selection: for printing- technical graphics, select Relative Colorimetric
- photographic images, select Perceptual
- simple bar charts & plots, select Saturation
Figure 6 Soft (onscreen) proof of Adobe RGB 1998 as the image profile, and U.S. Web Coated (SWOP) as the output (printer's) profile
III. Suggested Color Settings for Illustrator (Administrator Only)
IV. References
- Norman Koren Photography Page (www.normankoren.com)