by Thomas Bachand, ©2002-2005
In our last issue I covered the basics of color management. This time I'm going to take things up a notch for those with a color critical workflow.
Last time I gave a simplified description of profiles as a means to describe a device's color space and bias. In truth, profiles are much more than this. To describe a device's color characteristics we must first have a comprehensive description of the range of color, or gamut, a device can produce. Going one step further, since profiles are being applied to images, they are a vehicle for describing color gamuts, whether of a device or an image, and how they compare against a common standard. To accomplish this heavy lifting, dozens of variables are required.
In basic color management packages these variables take on predetermined values. The more advanced color management tools unlock access to these variables for customization, tweaking, and evaluation. Key to this profile control is the support of third-party calibration tools, namely spectrophotometers, or strip readers, for reading the raw data for creating printer (output) profiles. Even though these solutions also support colorimeters for monitor calibration, this is a lesser benefit as colorimeters come packaged with their own software. For scanner profiling these advanced color management tools utilize IT8 targets as described in part one.
Once the profiles are created, the heavy lifting is done. On the Mac, the profiling applications place them into the Colorsync folder for immediate access. The monitor profile you created should already be selected in the display preferences. As the scanner profile is somewhat contingent upon the film you are scanning and the calibration target used to create the profile, you will have to reset the profile selected in your scan settings every time you change film types.
In Adobe Photoshop your key tools are the Color Setting dialogue and the Proof Setup dialogue under the View menu.
The Color Settings feature gives you access to two tools of particular note. First, select an appropriate color space. The Pro Photo RGB color space is a very large color space for those working with hi-res scans and tight color tolerances. Often, the color gamut of high-end scans, such as created by the Imacon scanners by Hasselblad or the drum scans offered by professional labs, and the color gamut of quality desktop inkjet printers, exceed the color gamut of the working color space. Those colors falling out of gamut are clipped. A very large working color space, such as Pro Photo RGB, insures that colors are converted as accurate as possible as you move from scan to print. The Adobe RGB 1998 color space, while smaller, is a large and accurate working space that is becoming an industry standard and is sufficient for most professional workflows. Unless you are absolutely clear on the color space required for final output, scan into and work in the Adobe 1998 color space.
For color conversion, Adobe ACE engine is considered the best thing going. Through the Proof Setup>Customize feature your individual output profiles can be added to the menu. For more accurate proofing be sure to check "Simulate Paper White." Black Point Compensation is generally appropriate for RGB to RGB workflows and less likely to be used in CMYK workflows. For more detailed information on setting up Photoshop there are plenty of excellent resources on the web. See the end of this article for a list of important links.
Finally, the profile selected in your print dialogue box will be contingent upon the print settings, ink type, and paper used to create that profile. As your color swatches should have been created with your printer's color management off, be sure it is turned off. As this misleads the print preview, take a leap of faith and click directly on print.
As a final caveat, I would like to stress that no color managed workflow is going to be completely accurate to your eye. The differences in how color is seen by the scanner, display, and the print make this impossible. As you gain experience and an eye for color, the idiosyncracies of your workflow will become evident. In fact, at the risk of sounding like a huckster, once you've become acclimated, I think you'll be pleased with the consistency of your results.
For more on the color managed workflow, check out:
Thomas Bachand has been both Editor and Webmaster for ASMP Northern California. When not consulting on computer and Internet projects, he can be found photographing landscapes, travel and architecture. His photography, web , and writing portfolios can be found on-line at www.thomasbachand.com.