Use of Digital Cameras as the Image Input Devices in the Prepress Workflow

Digital photography has started to replace scanning as a method of capturing photographs and is especially useful in catalog and product photography. Just as scanning can benefit from color characterization, so too can digital photography, Figure 2-18. Digital cameras present a challenge to characterize, however, because they involve more variables. In comparison to a scanner, a digital camera can be used with different light sources and captures the added dimension of depth. Color management of digital camera input is most useful in studio photography, where lighting and scene can be standardized.

Due to potential differences in the way they record color, each combination of camera (or camera back) and lights will probably need its own profile. If a "raw" digital photography produces color values that are much different than those of the characterization target, the color management program may not be able to make a color transformation that works. Therefore, the profile may need to be made with standardized adjustments in the operating software--for example, exposure, tone reproduction, and color balance.

Like a scanner operator, the digital photographer who wants to characterize input will need and IT8.7/2 reflective scanner characterization target, an accompanying IT8.7/2 data reference file of target measurements, and a color management program for making scanner profiles. To make a camera profile:

1.  Place the IT8.7/2 target in the center of the scene, making sure the target is squarely in front of the camera.

2.  Expose a digital photograph of the IT8.7/2 Crop the target so the final image is of a file size recommended by the color management software publisher (e.g., 1.5~5.0MB). Save in RGB-TIFF format (or as recommended by the software publisher).

3.  Open the IT8.7/2 scan in the color management program, along with the IT8.7/2 data reference file, and make the profile. Apply the profile using the Apple ColorSync Plug-in filters or other ColorSync-compatible program.

Users familiar with the basic theory of the IT8.7/2 target will realize that the color transformation required for accurate reproduction may be different for photographic dyes than for other subject material. For this reason, some color management programs like Candela® Color Synergy® and Color Solutions ColorBlind offer the option of using a different input target, such as the GretagMacbeth ColorChecker or a user-defined palette.

The work of Stephen Johnson, a digital photographer who uses color management, has been featured in several posters from Radius Inc. Johnson has not found input characterization useful for field photography with his Dicomed digital cameras. "They have too wide a gamut for conventional targets." he said. Johnson does use a calibrated, characterized Radius PressView display for soft proofing. He outputs photographs to an IRIS inkjet proofer on rag paper, which has been profiled with Color savvy, GretagMacbeth ProfileMaker, and ColorBlind. His Radius posters were output using Photoshop separation tables supplied by Radius.