UPDIG Guidelines, Version 3.0
ICC Color Management
ICC profile-based color management is the standard. ICC profiles define color information in standard terms necessary for proper reproduction of images. All devices (scanners, printers, monitors and, ideally, digital cameras) should be profiled and profiles should be embedded in image files. When opening files, software needs to be configured to preserve embedded profiles and to warn of mismatched profiles or of files with no embedded profiles.
Photoshop CS2 color settings dialog, highlighted to identify the options of particular concern for color management.
Camera profiles: It is possible, but not strictly necessary, to create custom camera profiles. Used properly, they can offer a different color look or speed the workflow by saving time in post-processing. Profiling packages are available from Gretag MacBeth and Integrated Color. The main issues with camera profiles are how well they work when the lighting changes from the profile setup, where and when the profiles should be applied, and how multiple cameras with separate profiles can be handled in a workflow. In addition, most digital camera sensors respond differently to tungsten lights and daylight, so at a minimum, you would need to have two profiles per camera for that reason alone. Another complication is that not all RAW processing programs support custom camera profiles. Given today’s technology, photographers have to decide which combination of color look and workflow they like, or at least can live with.
Adobe Camera RAW calibration: ACR is one example of a RAW processing application that has built-in camera profiles (one for daylight and one for tungsten) for each camera model it supports. Although ACR does not support custom camera profiles, it does have a Calibration feature that allows you to adjust your camera sensor’s response to a known color target such as the GretagMacbeth 24 color checker. The calibration process can be automated: Photograph the Macbeth 24 checker target, run Tom Fors’ AcrCalibrator script, name and save the resulting calibration. The calibration can be applied to all the RAW files of a particular camera model. Since Adobe Camera RAW applies different camera profiles for daylight and tungsten lighting, you need to run at least two calibrations. We say "at least" because the calibration may also change incrementally for different ASA/ISO settings. A good guide to this technique can be found at the Visual Vacations site.
Inkjet and dye-sub printers: You can easily bring printers (including desktop and wide-format printers) into a color-managed environment via profiles. If working with the manufacturer’s printer driver, turn off all color management and print a copy of the color target file. Next, measure the printed target with a spectrophotometer to generate a profile for accurate output on a particular paper or other medium. Repeat this process for each paper stock and ink type that you use. If you do not own profiling software or a spectrophotometer, you can use one of several service providers, such as Chromix. Most RIP (raster image processor) software offers profiles for a wide variety of papers. Many RIPs will also allow use of custom profiles.
Offset printing: Two organizations in the United States have produced standards for the printing industry that would allow for standardized CMYK profiles. They are the SWOP Committee (Specifications for Web Offset Publications), covering web presses, and GRACoL (General Requirements for Applications in Commercial Offset Lithography), which covers sheet-fed printing. The two standards, SWOP TR001, and GRACol’s DTR004, if widely adopted, would do away with the need to worry as much about custom CMYK formulas.
In Europe, organizations such as FOGRA, ECI (European Color Initiative), and IFRA work on standardization of the printing industry. They have published general color profiles for several printing conditions. These profiles, based on the ISO 12647-2 standard, can be downloaded from ECI. Several larger print houses recommend them as CMYK profiles for their production. They also have great acceptance as proofing profiles.
When a photographer has the expertise, it’s best to provide the printer with CMYK image files embedded with the printer’s custom CMYK profile. If the printer does not have a custom profile, it’s best to consult with the printer or the client’s production expert to determine the best color space for the delivered files. A standard Photoshop CMYK profile that matches the general press conditions — sheetfed coated or uncoated, or web coated or uncoated — may suffice, particularly if the printer adheres to ISO, SWOP or GRACol specifications. In this period of flux, communication is key. Profiles will also enable you to produce guide prints or aim prints (see a later page) for clients, providing a printed reference for the press operator to target for color-matching purposes.