The "gold standard" for graphic/photo editing is PhotoShop, but it is too expensive for we mere mortals. For those who may be actually working on such things, though, the following, from PC Magazine April 9, 2002 may be of interest:

Rescue Poor Images with Science Fiction
BY LES FREED
Everyone knows that Adobe Photoshop can work miracles with old faded and poorly exposed images, but fixing the color and tonal balance of such in image takes time. Two new Photoshop plug-ins ($50 each) can make the fixes in just a few clicks.
Applied Science Fiction's Digital ROC and Digital SHO install as Photoshop filters. Digital ROC operates primarily on the images color balance and it works well with images that havc a strong color cast, faded colors from aging, or incorrect colors from poor lighting conditions. Digital SHO operates on the images exposure balance restoring detail lost because of strong over- or underexposure Installation takes only a few minutes, and both filters work with all versions of Photoshop from 5.0 on (Including Photoshop Elements) as well as with Adobe PhotoDeluxe 4.0 and later. Operation couldn't be much simpler. To repair an image just open thc image filc and select Digital ROC or Digital SHO from the Filters menu. Both filters provide a preview window so you can see the effect of the filter before you apply the filter to the image.
Our first impression was that these filters don t do anything that a skilled Photoshop user couldn't do, but we were wrong: Both filters consistently produced better images than we could produce manually—and in a fraction of the time. Both are excellent and affordable tools for your Photoshop arsenal.
Digital ROC and Digital SHO
Direct price: $50 each. Requires: 64MB RAM; Microsoft Windows 98 SE, NT 4.0 with SP6A, 2000, Me, and XP.
Applied Science Fiction Inc., 512-651-6200, www.asf.com.

I've found PC Magazine to be a reasonably reliable source for information of this sort, but *usual disclaimer* have no personal knowledge about these programs. Since PhotoShop 7.0 lists for $609 (US) it's not likely that I'll get any experience with them soon.

John