I am reproducing and retouching a series of very faded and discolored prints. All of these due to the wishes of the owner are to remian in their frames. This compromises the final results significantly, but also requires that I use a camera. I might add my personal view is using a camera or scanner is a toss up, and where a camera and propper copy stand/lighting might offer the greatest potential, for most people a quality flatbed scanner may be the easier and more reliable solution.
I wanted to mention that I took advantage of Kodak's free trial of their Digital ROC plugin V 2.0 . The print I tested was severely discolored. I compared my initial adustments to a copy corrected by Digital ROC. Regarding accuracey of color correction Digital ROC was better, and it appears to have reduced some of the mildew/unidentified growth on this particualr print. What I did not like about the Digital ROC adjustments is A) that it seemed to clip the highlights and shadow even though I backed off the "Contrast Ajustments" to 0%. B ) the adjustments are limited and particularly the "Brightness" adjustment I found to offer minimal control. Still it offers a quick option and one that can get you very close to where you want to be, from which you can make additional final adjustments. There are other similiar tools that others may want share their experience with. I still like to think if a tool can do it I can do it better, but that often means spending allot more time than may be justified for a particular job.
One more note these plugins are often bundled with the better flatbed scanners.
If you decide to use your camera and tripod keep these things in mind. The two biggest challenges will be even illumination of the print and eliminating reflections. Reflections can come from both your lighting source and reflections from the environment you are shooting in including your camera and tripod. Black masking tape is very usefull to cover up reflections from camera and tripod. A good way to eliminate reflections from the room or area in which are shooting is to place a large black cloth/backdrop directly behind the camera (idealy place the print on a black background as well). If this is more than you care to deal with, a polarizing filter can sometimes be effective as well, although I prefer to not use one. If your camera has a spot meter, meter your print left, center, right from top to bottom a grid of 3 x 3 would be a decent starting point. Using an incident light meter at the print is very useful as well. The goal is to keep your readings across the print or work being copied within 1/3 of a stop of each other. That covers the basics I think, and also gives you an idea of why a flatbed scanner has its advantages.
Here are a couple of links you might find helpful:http://www.plantpath.cornell.edu/PhotoLab/...opyLighting.htmhttp://www.videomaker.com/article/6807/